BACKGROUND Helicobacter pylori(H.pylori)is a Gram-negative bacterium that relies on flagellar motility to colonize the stomach,damaging the gastric mucosa through various mechanisms and leading to various digestive di...BACKGROUND Helicobacter pylori(H.pylori)is a Gram-negative bacterium that relies on flagellar motility to colonize the stomach,damaging the gastric mucosa through various mechanisms and leading to various digestive disorders.Accurate assessment and precise treatment are essential in initial intensive therapy.AIM To investigate the efficacy and safety of a vonoprazan(VPZ)-based triple regimen for first-line eradication of H.pylori in China.METHODS This multicenter noninferior randomized controlled trial(June 2022 to November 2023)involved 524 H.pyloripositive patients across 19 centers in Shandong,China.Participants were randomized to 14-day esomeprazole/bismuth/amoxicillin/clarithromycin(EBAC),14-day VPZ/amoxicillin/clarithromycin(VACa),or 10-day VPZ/amoxicillin/clarithromycin(VACb)-all administered twice daily.Primary outcomes(eradication rates)were assessed via intention-to-treat(ITT)and per-protocol(PP)analyses.Secondary endpoints included adverse events and adherence.Noninferiority testing andχ^(2)tests were used for statistical comparisons.RESULTS A total of 524 patients participated in this study.In ITT analysis,the eradication rates of the EBAC,VACa,and VACb groups were 72.6%(127/175),88.0%(154/175),and 83.3%(145/174),respectively(P=0.001).The difference in the eradication rate between the EBAC and VPCa groups was 15.4%[95%confidence interval(CI):7.3-23.6,P<0.001],and that between the EBAC and VACb groups was 10.8%(95%CI:2.1-19.4,P=0.018).In PP analysis,the eradication rates of the EBAC,VACa,and VACb groups were 81.4%(127/156),93.9%(154/164),and 90.6%(145/160),respectively(P=0.001).There was no significant difference in the incidence of adverse reactions among the three groups,which were 36.6%,33.8%and 29.6%,respectively(P=0.50).CONCLUSION VPZ-based triple therapies demonstrate noninferiority to 14-day bismuth-containing regimens,with the 10-day regimen showing comparable efficacy and similar adverse event rates.展开更多
A metallurgical model for austenite coarsening in the coarse-grained heat-affected zone(CGHAZ)containing titanium nitride(TiN)precipitation was studied.Unlike traditional methods estimating pinning capability based on...A metallurgical model for austenite coarsening in the coarse-grained heat-affected zone(CGHAZ)containing titanium nitride(TiN)precipitation was studied.Unlike traditional methods estimating pinning capability based on the precipitation size after welding,a proposed dissolution and coarsening model was applied to study the changes in TiN precipitation size and the associated pinning forces.The transmission electron microscope was used to analyze the size distribution of TiN particles before and after the welding thermal cycle.The size distribution showed a log-normal distribution before the thermal cycle.The prediction of post-thermal cycle size distributions with the proposed model was in agreement with the experimental results.Considering the short holding time at high temperature during welding,the thermodynamic stability conditions required for limiting grain size model cannot be achieved.A simple kinetic model for the prediction of austenite grain size in CGHAZ was established.Finally,the predicted austenite grain sizes agree better with experimental results than the conventional approach.展开更多
The effect of processing parameters such as hot rolling and heat treatment on microstructure and mechanical properties was investigated for a new 0.27mass% C and Ni, Mo-free low alloy martensitic abrasion resistant st...The effect of processing parameters such as hot rolling and heat treatment on microstructure and mechanical properties was investigated for a new 0.27mass% C and Ni, Mo-free low alloy martensitic abrasion resistant steel. The three-body impact abrasive wear behavior was also analyzed. The results showed that two-step controlled rolling besides quenching at 880 ℃ and tempering at 170 ℃ could result in optimal mechanical property., the Brinell hardness, tensile strength, elongation and --40 ℃ impact toughness were 531, 1530 MPa, 11.8% and 58 J, re- spectively. The microstructure was of fine lath martensite with little retained austenite. Three-body impact abrasive wear results showed that wear mechanism was mainly of plastic deformation fatigue when the impact energy was 2 J, and the relative wear resistance was 1.04 times higher than that of the same grade compared steel under the same working condition. The optimal hardness and toughness match was the main reason of higher wear resistance.展开更多
Through the thermo-mechanical control process （TMCP）, a high Nb low Mo fire resistant steel with the yield strength （YS） of 521 MPa at room temperature （RT） and 360 MPa at elevated temperature （ET） of 600 ℃ w...Through the thermo-mechanical control process （TMCP）, a high Nb low Mo fire resistant steel with the yield strength （YS） of 521 MPa at room temperature （RT） and 360 MPa at elevated temperature （ET） of 600 ℃ was developed based on MX （M=Nb, V, Mo; X=C,N） precipitation strengthening. A series of tensile and con- stant load tests were conducted to study the mechanical properties at ET. The dynamic continuous cooling transfor- mation （CCT） as well as precipitation behavior of microalloy carbonitride was investigated by means of thermal sim- ulator and electron microscopy approaches. Results showed that the failure temperature of tested steel was deter- mined as 653 ℃, and the granular bainite was obtained when the cooling rate was higher than 10 ℃/s. In the rolled state, a certain amount of M/A islands was observed. During heating from RT to ET, M/A islands disappeared, and cementites and high dense compound precipitates （Nb, Mo, V）C with size of less than 10 nm precipitated in ferrite at ET （600 ℃）, which resulted in precipitation strengthening at ET.展开更多
During acute reperfusion,the expression profiles of long noncoding RNAs in adult rats with focal cerebral ischemia undergo broad changes.However,whether long noncoding RNAs are involved in neuroprotective effects foll...During acute reperfusion,the expression profiles of long noncoding RNAs in adult rats with focal cerebral ischemia undergo broad changes.However,whether long noncoding RNAs are involved in neuroprotective effects following focal ischemic stroke in rats remains unclear.In this study,RNA isolation and library preparation was performed for long noncoding RNA sequencing,followed by determining the coding potential of identified long noncoding RNAs and target gene prediction.Differential expression analysis,long noncoding RNA functional enrichment analysis,and co-expression network analysis were performed comparing ischemic rats with and without ischemic postconditioning rats.Rats were subjected to ischemic postconditioning via the brief and repeated occlusion of the middle cerebral artery or femoral artery.Quantitative real-time reverse transcription-polymerase chain reaction was used to detect the expression levels of differentially expressed long noncoding RNAs after ischemic postconditioning in a rat model of ischemic stroke.The results showed that ischemic postconditioning greatly affected the expression profile of long noncoding RNAs and mRNAs in the brains of rats that underwent ischemic stroke.The predicted target genes of some of the identified long noncoding RNAs(cis targets)were related to the cellular response to ischemia and stress,cytokine signal transduction,inflammation,and apoptosis signal transduction pathways.In addition,15 significantly differentially expressed long noncoding RNAs were identified in the brains of rats subjected to ischemic postconditioning.Nine candidate long noncoding RNAs that may be related to ischemic postconditioning were identified by a long noncoding RNA expression profile and long noncoding RNA-mRNA co-expression network analysis.Expression levels were verified by quantitative real-time reverse transcription-polymerase chain reaction.These results suggested that the identified long noncoding RNAs may be involved in the neuroprotective effects associated with ischemic postconditioning following ischemic stroke.The experimental animal procedures were approved by the Animal Experiment Ethics Committee of Kunming Medical University(approval No.KMMU2018018)in January 2018.展开更多
AIM： To investigate the histological and ultra-structural characteristics of liver graft during different of warm ischemia time （WIT） in rats and to predict the maximum limitation of liver graft to warm ischemia. M...AIM： To investigate the histological and ultra-structural characteristics of liver graft during different of warm ischemia time （WIT） in rats and to predict the maximum limitation of liver graft to warm ischemia. METHODS： The rats were randomized into 7 groups undergoing warm ischemia injury for 0, 10, 15, 20, 30, 45 and 60 min, respectively. All specimens having undergone warm ischemia injury were investigated dynamically by light and electron microscopy, and histochemistry staining. After orthotopic liver transplantation （OLT）, the recovery of morphology of liver grafts after 6, 24 and 48 h was observed. RESULTS： The donor liver from non-heart-beating donors （NHBD） underwent ischemia injury both in the warm ischemia period and in the reperfusion period. Morphological changes were positively related to warm ischemia injury in a time-dependent manner during the reperfusion period. The results demonstrated that different degrees of histocyte degeneration were observed when WIT was within 30 min, and became more severe with the prolongation of WIT, no obvious hepatocyte necrosis was noted in any specimen. In the group undergoing warm ischemia injury for 45 min, small focal necrosis occurred in the central area of hepatic Iobule first. In the group undergoing warm ischemia injury for 60 rain, patchy or diffused necrosis was observed and the area was gradually extended, while hepatic sinusoid endothelial cells were obviously swollen. Hepatic sinusoid was obstructed and microcirculation was in disorder.CONCLUSION： The rat liver graft undergoing warm ischemia injury is in the reversible stage when the WIT is within 30 min. The 45 min WIT may be a critical point of rat liver graft to endure warm ischemia injury. When the WIT is over 60 min, the damage is irreversible.展开更多
China is rich in abundant lithium resources characterized by considerable reserves and a concentrated distribution of metallogenic zones or belts,with proven reserves of 4046.8×10^(3) t(calculated based on Li_(2)...China is rich in abundant lithium resources characterized by considerable reserves and a concentrated distribution of metallogenic zones or belts,with proven reserves of 4046.8×10^(3) t(calculated based on Li_(2)O)by 2021.China is also a big consumer of lithium.By 2019,China’s lithium consumption in the battery sector alone had reached 99×10^(3) t,with an average annual growth rate of nearly 26%.China has become the world’s largest importer of lithium resources,showing a severely unbalanced relationship between supply and demand for lithium resources.Therefore,there is an urgent need for the prospecting,exploitation,and study of lithium resources in China.This study collected,organized,and summarized the data on the major lithium deposits in China,analyzed and compared the spatial-temporal distribution patterns,geological characteristics,and metallogenic regularity of these lithium deposits,and summarized the prospecting and research achievements over the last decade.The major lithium deposits in China are distributed in provinces and regions such as Qinghai,Jiangxi,Sichuan,Tibet,and Xinjiang.These deposits are mostly small in scale.According to different genetic types,this study divided lithium deposits into granitic pegmatite type,granite type,saline lake brine type,underground brine type,and sedimentary type,as well as new types including hot spring type and magmatic-hydrothermal type,and summarized the characteristics and key metallogenic factors of these different types of deposits.Sixteen metallogenic prospect areas of lithium deposits were delineated according to the deposit types and the distribution patterns of metallogenic belts.The paper introduced the research progress in major metallogenic models and lithium extraction techniques made over the past decade.Based on the comprehensive analysis of the prospecting potential of lithium deposits,the authors concluded that the future prospecting of lithium resources in China should focus on lithium metallogenic belts,the deep and peripheral areas of currently determined large-scale pegmatite-type lithium deposits,geophysical-geochemical anomalous areas with mineralization clues,and areas with developed large-scale low-grade associated granite-type and sedimentary lithium resources.The study aims to serve as a guide for the future prospecting of lithium deposits in China.展开更多
The grey wolf （Canis lupus） is one of the most widely distributed terrestrial mammals, and its distribution and ecology in Europe and North America are largely well described. However, the distribution of grey wolve...The grey wolf （Canis lupus） is one of the most widely distributed terrestrial mammals, and its distribution and ecology in Europe and North America are largely well described. However, the distribution of grey wolves in southern China is still highly controversial. Several well-known western literatures stated that there were no grey wolves in southern China, while the presence of grey wolves across China has been indicated in A Guide to the Mammals of China, published by Princeton University Press. It is essential to solve this discrepancy since dogs may have originated from grey wolves in southern China. Therefore, we systematically investigated Chinese literatures about wild animal surveys and identified more than 100 articles and books that included information of the distribution of grey wolves in China. We also surveyed the collections of three Chinese natural museums and found 26 grey wolf skins specimens collected across China. Moreover, we investigated the fossil records in China and identified 25 archaeological sites with wolf remains including south China. In conclusion, with the comprehensive summary of Chinese literatures, museum specimens and fossil records, we demonstrate that grey wolves do distribute across all parts of the Chinese mainland, including the most southern parts.展开更多
As the only working dog independently developed and bred in China,Chinese Kunming dog(CKD)was approved as a new breed by the Chinese National Livestock and Poultry Genetics Commission in 2007.Now CKD is widely used by...As the only working dog independently developed and bred in China,Chinese Kunming dog(CKD)was approved as a new breed by the Chinese National Livestock and Poultry Genetics Commission in 2007.Now CKD is widely used by the Chinese army and police and has been exported to Singapore,Thailand,Vietnam,North Korea,and other more than 10 countries as working dog.Previously published studies of CKD have focused on coat color genetics(Wang et al.2013)and reproduction performance(Wei et al.2018).The study by Wang et al.(2013)pointed out that the breed of CKD was developed in the 1950s by hybridizing German shepherd dogs(GSDs)imported from the Soviet Union with Kunming indigenous village dogs.展开更多
The nanometer-size carbides formed in ferrite matrix of Nb-Ti microalloyed steel at different finishing cooling temperatures and holding time have been investigated. The characteristics of nanometer-size carbides in f...The nanometer-size carbides formed in ferrite matrix of Nb-Ti microalloyed steel at different finishing cooling temperatures and holding time have been investigated. The characteristics of nanometer-size carbides in ferrite were observed by transmission electron microscopy, and mechanical properties of ferrite were detected by a nano-hardness tester. The results showed that interphase precipitation and diffusion precipitation were observed at different finishing cooling temperatures, and the interphase precipitation was planar and curved. Sheet spacing of inter-phase precipitation increased with the increase of finishing cooling temperature and changed a little when holding for 50--1000 s. Interphase precipitation shows higher nano-hardness at 640℃ compared with diffusion precipitation at 600℃, and the contribution of interphase precipitation to the mechanical properties of ferrite was larger than that of diffusion precipitation.展开更多
The hydrogen embrittlement(HE)fracture of advanced high-strength steels used in lightweight automobiles has received increasing public attention.The source,transmission,and movement of hydrogen,characterization parame...The hydrogen embrittlement(HE)fracture of advanced high-strength steels used in lightweight automobiles has received increasing public attention.The source,transmission,and movement of hydrogen,characterization parameters,and test methods of HE,as well as the characteristics and path of HE fractures,are introduced.The mechanisms and modes of crack propagation of HE and hydrogen-induced delayed fracture are reviewed.The recent progress surrounding micro and macro typical fracture characteristics and the influencing factors of HE are discussed.Finally,methods for improving HE resistance can be summarized as follows:(1)reducing crystalline grain and inclusion sizes(oxides,sulfides,and titanium nitride),(2)controlling nano-precipitates(niobium carbide,titanium carbide,and composite precipitation),and(3)increasing residual austenite content under the reasonable tension strength of steel.展开更多
The precipitation behavior of nanometer-sized carbides in ferrite in Nb-V-bearing low-carbon steel was studied by electron microscopy and nanoindentation hardness measurements. The results indicated that interphase pr...The precipitation behavior of nanometer-sized carbides in ferrite in Nb-V-bearing low-carbon steel was studied by electron microscopy and nanoindentation hardness measurements. The results indicated that interphase precipitation and random precipitation could occur simultaneously for the specimen isothermally treated at 700 ℃ for 60 min, while in other specimens, only random precipitation was observed. This phenomenon might be explained by mass balance criterion during the diffusional phase transformation. Nanohardness result indicated that the average hardness of the specimens isothermally held at 600 ℃ for 20 min was 3.87 GPa. For the specimen isothermally holding at 650 ℃ for 20 min, the average hardness was 4.10 GPa and the distribution of the nanohardness was in a narrower range compared with that of the specimen isothermal holding at 600 ℃ for 20 min. These implied that the carbides in the specimens isothermal treated at 650℃ were more uniformly dispersed, and the number density of the carbides was greater than that treated at 600 ℃. Using Ashby-Orowan model, the contribution of precipitation strengthening to yield strength was estimated to be 110 MPa for the specimen isothermally treated at the temperature of 650 ℃ for 20 min.展开更多
Carbon steel strips with different phosphorus and carbon contents were produced by using the twin roll strip casting process. Fine grains and dendrite structure were observed in high-P steels. Negative phosphorus segr...Carbon steel strips with different phosphorus and carbon contents were produced by using the twin roll strip casting process. Fine grains and dendrite structure were observed in high-P steels. Negative phosphorus segregation was found in strip cast high-P and high-C steels. For the steels with different carbon contents, phosphorus distribution in the thickness direction of the strip is obviously different. This is because solutes are redistributed in the melting pool and the phosphorus segregation rate is associated with the length of the mushy zone and the phosphorus solubility in different phases. Phosphorus as a solute in ferrite can lead to the higher hardness and strength with lower plastic propertyies.展开更多
The effect of inclusion-induced nucleation on hot-rolled steel base metal was evaluated in comparison with welding heataffected zone(HAZ).Microstructure and mechanical properties of hot-rolled low-carbon steel contain...The effect of inclusion-induced nucleation on hot-rolled steel base metal was evaluated in comparison with welding heataffected zone(HAZ).Microstructure and mechanical properties of hot-rolled low-carbon steel containing Ti–Ca oxide particles were studied.The results showed that inclusions in Ti–Ca deoxidized steel distributed dispersely and were effective for intragranular acicular ferrite nucleation.Under hot rolling and controlled cooling conditions,microstructure in steel base metal was significantly refined and mainly consisted of acicular ferrite and intragranular bainite,which exhibited higher strength and excellent toughness.The microstructural evolution behavior followed the process that acicular ferrite plates divided the austenite grain,intragranular bainite packets formed between interlocking acicular ferrite plates,and the remaining austenite decomposed into fine polygonal ferrite grains.The resultant complex microstructure improved the impact toughness significantly.By comparison,in HAZ microstructure,laminar grain boundary ferrite having similar crystallography orientation showed adverse effect on toughness.展开更多
Based on medium plate runout table ultra-fast cooling( UFC)-accelerated cooling equipment( ACC) system,a heat transfer coefficient model was constructed. Firstly,according to the measured data,heat transfer coefficien...Based on medium plate runout table ultra-fast cooling( UFC)-accelerated cooling equipment( ACC) system,a heat transfer coefficient model was constructed. Firstly,according to the measured data,heat transfer coefficients under different roll speed and water volume were calculated by using an inverse heat conduction method. Secondly,a monofactorial heat transfer coefficient calculation formula was obtained. Finally,the heat transfer coefficient model based on medium plate runout table UFC-ACC system was constructed by intercept function,slope function,interaction influence function and linear or nonlinear influencing factors. The precision of these models was validated by comparing model prediction value with measured data,and the results were in good agreement with practical needs,and the average deviation was less than 5%.展开更多
By measuring the expansion curves of a C-Mn steel at different cooling rates by using an MMS-300 thermo- mechanical simulator, continuous cooling transformation curves were obtained. The new process ＂ultra fast cool...By measuring the expansion curves of a C-Mn steel at different cooling rates by using an MMS-300 thermo- mechanical simulator, continuous cooling transformation curves were obtained. The new process ＂ultra fast cooling＋ laminar cooling＂ was simulated and the effects of ultra fast cooling ending temperature on microstructure had also been investigated. The hot rolling experiment was done by adopting ＂high temperature rolling-[-forepart ultra fast cooling＂ technologies at laboratory scale. The results revealed that ultra fast cooling can delay the decrease of disloca- tion density and refine ferrite grains. Diversity control of the microstructure and phase transformation strengthening can be realized by changing the ultra fast cooling ending temperature. With the decrease of ultra fast cooling ending temperature, the strength and toughness increase, but plasticity does not decrease obviously. The new technique can improve the yield strength by over 50 MPa. Therefore, the upgrade of mechanical properties of C-Mn steel can be realized by using ＂high temperature rolling＋ ultra fast cooling＋laminar cooling＂ technique. Compared with ＂low temperature rolling with large deformation degree＂ technique, this new technology can decrease the roiling force and in- crease the production efficiency.展开更多
BACKGROUND The gut microbiota(GM)has been proven to play a role in the regulation of host lipid metabolism,which provides a new theory about the pathogenesis of dyslipidemia.However,the associations of GM with dyslipi...BACKGROUND The gut microbiota(GM)has been proven to play a role in the regulation of host lipid metabolism,which provides a new theory about the pathogenesis of dyslipidemia.However,the associations of GM with dyslipidemia based on sex differences remain unclear and warrant elucidation.AIM To investigate the associations of GM features with serum lipid profiles based on sex differences in a Chinese population.METHODS This study ultimately recruited 142 participants(73 females and 69 males)at Honghui Hospital,Xi’an Jiaotong University.The anthropometric and blood metabolic parameters of all participants were measured.According to their serum lipid levels,female and male participants were classified into a high triglyceride(H_TG)group,a high total cholesterol(H_CHO)group,a low high-density lipoprotein cholesterol(L_HDL-C)group,and a control(CON)group with normal serum lipid levels.Fresh fecal samples were collected for 16S rRNA gene sequencing.UPARSE software,QIIME software,the RDP classifier and the FAPROTAX database were used for sequencing analyses.RESULTS The GM composition at the phylum level included Firmicutes and Bacteroidetes as the core GM.Different GM features were identified between females and males,and the associations between GM and serum lipid profiles were different in females and males.The GM features in different dyslipidemia subgroups changed in both female patients and male patients.Proteobacteria,Lactobacillaceae,Lactobacillus and Lactobacillus_salivarius were enriched in H_CHO females compared with CON females,while Coriobacteriia were enriched in L_HDL-C females.In the comparison among the three dyslipidemia subgroups in females,Lactobacillus_salivarius were enriched in H_CHO females,and Prevotellaceae were enriched in L_HDL-C females.Compared with CON or H_TG males,Prevotellaceae,unidentified_Ruminococcaceae,Roseburia and Roseburia_inulinivorans were decreased in L_HDL-C males(P value<0.05),and linear discriminant analysis effect size analysis indicated an enrichment of the above GM taxa in H_TG males compared with other male subgroups.Additionally,Roseburia_inulinivorans abundance was positively correlated with serum TG and total cholesterol levels,and Roseburia were positively correlated with serum TG level.Furthermore,Proteobacteria(0.724,95%CI:0.567-0.849),Lactobacillaceae(0.703,95%CI:0.544-0.832),Lactobacillus(0.705,95%CI:0.547-0.834)and Lactobacillus_salivarius(0.706,95%CI:0.548-0.835)could distinguish H_CHO females from CON females,while Coriobacteriia(0.710,95%CI:0.547-0.841),Coriobacteriales(0.710,95%CI:0.547-0.841),Prevotellaceae(0.697,95%CI:0.534-0.830),Roseburia(0.697,95%CI:0.534-0.830)and Roseburia_inulinivorans(0.684,95%CI:0.520-0.820)could discriminate H_TG males from CON males.Based on the predictions of GM metabolic capabilities with the FAPROTAX database,a total of 51 functional assignments were obtained in females,while 38 were obtained in males.This functional prediction suggested that cellulolysis increased in L_HDL-C females compared with CON females,but decreased in L_HDL-C males compared with CON males.CONCLUSION This study indicates associations of GM with serum lipid profiles,supporting the notion that GM dysbiosis may participate in the pathogenesis of dyslipidemia,and sex differences should be considered.展开更多
Grain-oriented 4.5 wt% Si and 6.5 wt% Si steels were produced by strip casting, warm rolling, cold rolling, primary annealing, and secondary annealing. Goss grains were sufficiently developed and covered the entire su...Grain-oriented 4.5 wt% Si and 6.5 wt% Si steels were produced by strip casting, warm rolling, cold rolling, primary annealing, and secondary annealing. Goss grains were sufficiently developed and covered the entire surface of the secondary recrystallized sheets. The microstructure and texture was characterized by OM, EBSD, TEM, and XRD. It was observed that after rolling at 700 ℃, the 6.5 wt% Si steel exhibited a considerable degree of shear bands, whereas the 4.5 wt% Si steel indicated their rare presence. After primary annealing, completely equiaxed grains showing strong y-fiber texture were presented in both alloys. By comparison, the 6.5 wt% Si steel showed smaller grain size and few favorable Goss grains. Additionally, a higher density of fine precipitates were exhibited in the 6.5 wt% Si steel, leading to a ~ 30-s delay in primary recrystallization. During secondary annealing, abnormal grain growth of the 6.5 wt% Si steel occurred at higher temperature compared to the 4.5 wt% Si steel, and the final grain size of the 6.5 wt% Si steel was greater. The magnetic induction B8 of the 4.5 wt% Si and the 6.5 wt% Si steels was 1.75 and 1.76 T, respectively, and the high- frequency core losses were significantly improved in comparison with the non-oriented high silicon steel.展开更多
In this study, the effect of cooling rates on microstructures and mechanical properties in a Al-bearing hot-rolled transformation- induced plasticity steel was investigated. The experiments were carried out using hot ...In this study, the effect of cooling rates on microstructures and mechanical properties in a Al-bearing hot-rolled transformation- induced plasticity steel was investigated. The experiments were carried out using hot simulation machine and hot rolling mill, where the samples were cooled at different cooling rates. The results showed that with the increase in cooling rates, film-like retained austenite gradually disappeared and only blocky retained austenite was retained at higher cooling rates. The volume fraction of retained austenite was 9-11% at cooling rates of 0.05-1 ℃/s and 4-6% at cooling rates of 5-10 ℃/s. In addition, martensite/austenite island was observed because of the heterogeneous carbon distribution. The samples cooled at 0.05℃/s and 0.5 ℃/s exhibited excellent mechanical properties, with tensile strengths of 712 MPa and 726 MPa, total elongations of 42% and 36% and strength and ductility balances of 29.91 GPa% and 26.15 GPa%, respectively. During plastic deformation, the instantaneous work hardening exponent of the sample cooled at 0.05 ℃/s increased continuously until it reached the maximum value, while the instantaneous work hardening exponent of the sample cooled at 0.5℃/s remained stable.展开更多
基金Supported by Qilu Health Outstanding Young Talent Cultivation Project,No.QDFY-3839。
文摘BACKGROUND Helicobacter pylori(H.pylori)is a Gram-negative bacterium that relies on flagellar motility to colonize the stomach,damaging the gastric mucosa through various mechanisms and leading to various digestive disorders.Accurate assessment and precise treatment are essential in initial intensive therapy.AIM To investigate the efficacy and safety of a vonoprazan(VPZ)-based triple regimen for first-line eradication of H.pylori in China.METHODS This multicenter noninferior randomized controlled trial(June 2022 to November 2023)involved 524 H.pyloripositive patients across 19 centers in Shandong,China.Participants were randomized to 14-day esomeprazole/bismuth/amoxicillin/clarithromycin(EBAC),14-day VPZ/amoxicillin/clarithromycin(VACa),or 10-day VPZ/amoxicillin/clarithromycin(VACb)-all administered twice daily.Primary outcomes(eradication rates)were assessed via intention-to-treat(ITT)and per-protocol(PP)analyses.Secondary endpoints included adverse events and adherence.Noninferiority testing andχ^(2)tests were used for statistical comparisons.RESULTS A total of 524 patients participated in this study.In ITT analysis,the eradication rates of the EBAC,VACa,and VACb groups were 72.6%(127/175),88.0%(154/175),and 83.3%(145/174),respectively(P=0.001).The difference in the eradication rate between the EBAC and VPCa groups was 15.4%[95%confidence interval(CI):7.3-23.6,P<0.001],and that between the EBAC and VACb groups was 10.8%(95%CI:2.1-19.4,P=0.018).In PP analysis,the eradication rates of the EBAC,VACa,and VACb groups were 81.4%(127/156),93.9%(154/164),and 90.6%(145/160),respectively(P=0.001).There was no significant difference in the incidence of adverse reactions among the three groups,which were 36.6%,33.8%and 29.6%,respectively(P=0.50).CONCLUSION VPZ-based triple therapies demonstrate noninferiority to 14-day bismuth-containing regimens,with the 10-day regimen showing comparable efficacy and similar adverse event rates.
基金supported by the National Natural Science Foundation of China(U21A20116).
文摘A metallurgical model for austenite coarsening in the coarse-grained heat-affected zone(CGHAZ)containing titanium nitride(TiN)precipitation was studied.Unlike traditional methods estimating pinning capability based on the precipitation size after welding,a proposed dissolution and coarsening model was applied to study the changes in TiN precipitation size and the associated pinning forces.The transmission electron microscope was used to analyze the size distribution of TiN particles before and after the welding thermal cycle.The size distribution showed a log-normal distribution before the thermal cycle.The prediction of post-thermal cycle size distributions with the proposed model was in agreement with the experimental results.Considering the short holding time at high temperature during welding,the thermodynamic stability conditions required for limiting grain size model cannot be achieved.A simple kinetic model for the prediction of austenite grain size in CGHAZ was established.Finally,the predicted austenite grain sizes agree better with experimental results than the conventional approach.
基金Item Sponsored by National Basic Research Program of China(2010CB630801)
文摘The effect of processing parameters such as hot rolling and heat treatment on microstructure and mechanical properties was investigated for a new 0.27mass% C and Ni, Mo-free low alloy martensitic abrasion resistant steel. The three-body impact abrasive wear behavior was also analyzed. The results showed that two-step controlled rolling besides quenching at 880 ℃ and tempering at 170 ℃ could result in optimal mechanical property., the Brinell hardness, tensile strength, elongation and --40 ℃ impact toughness were 531, 1530 MPa, 11.8% and 58 J, re- spectively. The microstructure was of fine lath martensite with little retained austenite. Three-body impact abrasive wear results showed that wear mechanism was mainly of plastic deformation fatigue when the impact energy was 2 J, and the relative wear resistance was 1.04 times higher than that of the same grade compared steel under the same working condition. The optimal hardness and toughness match was the main reason of higher wear resistance.
基金Item Sponsored by National Basic Research Program of China(2010CB630805)
文摘Through the thermo-mechanical control process （TMCP）, a high Nb low Mo fire resistant steel with the yield strength （YS） of 521 MPa at room temperature （RT） and 360 MPa at elevated temperature （ET） of 600 ℃ was developed based on MX （M=Nb, V, Mo; X=C,N） precipitation strengthening. A series of tensile and con- stant load tests were conducted to study the mechanical properties at ET. The dynamic continuous cooling transfor- mation （CCT） as well as precipitation behavior of microalloy carbonitride was investigated by means of thermal sim- ulator and electron microscopy approaches. Results showed that the failure temperature of tested steel was deter- mined as 653 ℃, and the granular bainite was obtained when the cooling rate was higher than 10 ℃/s. In the rolled state, a certain amount of M/A islands was observed. During heating from RT to ET, M/A islands disappeared, and cementites and high dense compound precipitates （Nb, Mo, V）C with size of less than 10 nm precipitated in ferrite at ET （600 ℃）, which resulted in precipitation strengthening at ET.
基金the National Natural Science Foundation of China,No.31560295(to LYL)the Yunnan Applied Basic Research Projects of China,Nos.2018FE001(-016)(to WM),2018FE001(-163)(to LYL)the Research Innovation Team of Yunnan Province of China,No.2019HC022(to LYL).
文摘During acute reperfusion,the expression profiles of long noncoding RNAs in adult rats with focal cerebral ischemia undergo broad changes.However,whether long noncoding RNAs are involved in neuroprotective effects following focal ischemic stroke in rats remains unclear.In this study,RNA isolation and library preparation was performed for long noncoding RNA sequencing,followed by determining the coding potential of identified long noncoding RNAs and target gene prediction.Differential expression analysis,long noncoding RNA functional enrichment analysis,and co-expression network analysis were performed comparing ischemic rats with and without ischemic postconditioning rats.Rats were subjected to ischemic postconditioning via the brief and repeated occlusion of the middle cerebral artery or femoral artery.Quantitative real-time reverse transcription-polymerase chain reaction was used to detect the expression levels of differentially expressed long noncoding RNAs after ischemic postconditioning in a rat model of ischemic stroke.The results showed that ischemic postconditioning greatly affected the expression profile of long noncoding RNAs and mRNAs in the brains of rats that underwent ischemic stroke.The predicted target genes of some of the identified long noncoding RNAs(cis targets)were related to the cellular response to ischemia and stress,cytokine signal transduction,inflammation,and apoptosis signal transduction pathways.In addition,15 significantly differentially expressed long noncoding RNAs were identified in the brains of rats subjected to ischemic postconditioning.Nine candidate long noncoding RNAs that may be related to ischemic postconditioning were identified by a long noncoding RNA expression profile and long noncoding RNA-mRNA co-expression network analysis.Expression levels were verified by quantitative real-time reverse transcription-polymerase chain reaction.These results suggested that the identified long noncoding RNAs may be involved in the neuroprotective effects associated with ischemic postconditioning following ischemic stroke.The experimental animal procedures were approved by the Animal Experiment Ethics Committee of Kunming Medical University(approval No.KMMU2018018)in January 2018.
基金Supported by the Key Clinical Project of Minister of Public Health, No. 97040230
文摘AIM： To investigate the histological and ultra-structural characteristics of liver graft during different of warm ischemia time （WIT） in rats and to predict the maximum limitation of liver graft to warm ischemia. METHODS： The rats were randomized into 7 groups undergoing warm ischemia injury for 0, 10, 15, 20, 30, 45 and 60 min, respectively. All specimens having undergone warm ischemia injury were investigated dynamically by light and electron microscopy, and histochemistry staining. After orthotopic liver transplantation （OLT）, the recovery of morphology of liver grafts after 6, 24 and 48 h was observed. RESULTS： The donor liver from non-heart-beating donors （NHBD） underwent ischemia injury both in the warm ischemia period and in the reperfusion period. Morphological changes were positively related to warm ischemia injury in a time-dependent manner during the reperfusion period. The results demonstrated that different degrees of histocyte degeneration were observed when WIT was within 30 min, and became more severe with the prolongation of WIT, no obvious hepatocyte necrosis was noted in any specimen. In the group undergoing warm ischemia injury for 45 min, small focal necrosis occurred in the central area of hepatic Iobule first. In the group undergoing warm ischemia injury for 60 rain, patchy or diffused necrosis was observed and the area was gradually extended, while hepatic sinusoid endothelial cells were obviously swollen. Hepatic sinusoid was obstructed and microcirculation was in disorder.CONCLUSION： The rat liver graft undergoing warm ischemia injury is in the reversible stage when the WIT is within 30 min. The 45 min WIT may be a critical point of rat liver graft to endure warm ischemia injury. When the WIT is over 60 min, the damage is irreversible.
基金funded by the Major Research Plan of the National Natural Science Foundation of China(Grant No.92062217)the project of China Geological Survey(DD20190405).
文摘China is rich in abundant lithium resources characterized by considerable reserves and a concentrated distribution of metallogenic zones or belts,with proven reserves of 4046.8×10^(3) t(calculated based on Li_(2)O)by 2021.China is also a big consumer of lithium.By 2019,China’s lithium consumption in the battery sector alone had reached 99×10^(3) t,with an average annual growth rate of nearly 26%.China has become the world’s largest importer of lithium resources,showing a severely unbalanced relationship between supply and demand for lithium resources.Therefore,there is an urgent need for the prospecting,exploitation,and study of lithium resources in China.This study collected,organized,and summarized the data on the major lithium deposits in China,analyzed and compared the spatial-temporal distribution patterns,geological characteristics,and metallogenic regularity of these lithium deposits,and summarized the prospecting and research achievements over the last decade.The major lithium deposits in China are distributed in provinces and regions such as Qinghai,Jiangxi,Sichuan,Tibet,and Xinjiang.These deposits are mostly small in scale.According to different genetic types,this study divided lithium deposits into granitic pegmatite type,granite type,saline lake brine type,underground brine type,and sedimentary type,as well as new types including hot spring type and magmatic-hydrothermal type,and summarized the characteristics and key metallogenic factors of these different types of deposits.Sixteen metallogenic prospect areas of lithium deposits were delineated according to the deposit types and the distribution patterns of metallogenic belts.The paper introduced the research progress in major metallogenic models and lithium extraction techniques made over the past decade.Based on the comprehensive analysis of the prospecting potential of lithium deposits,the authors concluded that the future prospecting of lithium resources in China should focus on lithium metallogenic belts,the deep and peripheral areas of currently determined large-scale pegmatite-type lithium deposits,geophysical-geochemical anomalous areas with mineralization clues,and areas with developed large-scale low-grade associated granite-type and sedimentary lithium resources.The study aims to serve as a guide for the future prospecting of lithium deposits in China.
基金supported by grants from the National Natural Science Foundation of China(91531303)the 973 program(2013CB835200 and 2013CB835202)+3 种基金the Breakthrough Project of Strategic Priority Program of the Chinese Academy of Sciences(XDB13000000)grants from the Carl Trygger Foundationthe Agria and Swedish Kennel Club research foundationsupported by the Youth Innovation Promotion Association,Chinese Academy of Sciences
文摘The grey wolf （Canis lupus） is one of the most widely distributed terrestrial mammals, and its distribution and ecology in Europe and North America are largely well described. However, the distribution of grey wolves in southern China is still highly controversial. Several well-known western literatures stated that there were no grey wolves in southern China, while the presence of grey wolves across China has been indicated in A Guide to the Mammals of China, published by Princeton University Press. It is essential to solve this discrepancy since dogs may have originated from grey wolves in southern China. Therefore, we systematically investigated Chinese literatures about wild animal surveys and identified more than 100 articles and books that included information of the distribution of grey wolves in China. We also surveyed the collections of three Chinese natural museums and found 26 grey wolf skins specimens collected across China. Moreover, we investigated the fossil records in China and identified 25 archaeological sites with wolf remains including south China. In conclusion, with the comprehensive summary of Chinese literatures, museum specimens and fossil records, we demonstrate that grey wolves do distribute across all parts of the Chinese mainland, including the most southern parts.
基金supported by the National Key R&D Program of China(2019YFA0707101)Key Research Program of Frontier Sciences of the CAS(ZDBS-LY-SM011)+1 种基金Innovative Research Team(in Science and Technology)of Yunnan Province(201905E160019)G.-D.W.is supported by the Youth Innovation Promotion Association of CAS.
文摘As the only working dog independently developed and bred in China,Chinese Kunming dog(CKD)was approved as a new breed by the Chinese National Livestock and Poultry Genetics Commission in 2007.Now CKD is widely used by the Chinese army and police and has been exported to Singapore,Thailand,Vietnam,North Korea,and other more than 10 countries as working dog.Previously published studies of CKD have focused on coat color genetics(Wang et al.2013)and reproduction performance(Wei et al.2018).The study by Wang et al.(2013)pointed out that the breed of CKD was developed in the 1950s by hybridizing German shepherd dogs(GSDs)imported from the Soviet Union with Kunming indigenous village dogs.
基金Item Sponsored by National Natural Science Foundation of China(51104046)Fundamental Research Funds for Central Universities of China(N120407001,N120807001)
文摘The nanometer-size carbides formed in ferrite matrix of Nb-Ti microalloyed steel at different finishing cooling temperatures and holding time have been investigated. The characteristics of nanometer-size carbides in ferrite were observed by transmission electron microscopy, and mechanical properties of ferrite were detected by a nano-hardness tester. The results showed that interphase precipitation and diffusion precipitation were observed at different finishing cooling temperatures, and the interphase precipitation was planar and curved. Sheet spacing of inter-phase precipitation increased with the increase of finishing cooling temperature and changed a little when holding for 50--1000 s. Interphase precipitation shows higher nano-hardness at 640℃ compared with diffusion precipitation at 600℃, and the contribution of interphase precipitation to the mechanical properties of ferrite was larger than that of diffusion precipitation.
基金This work was financially supported by the State Key Laboratory of Vehicle NVH and Safety Technology(NVHSKL-202104)the innovation research group of universities in Chongqing(CXQT21030,CXQT19031).
文摘The hydrogen embrittlement(HE)fracture of advanced high-strength steels used in lightweight automobiles has received increasing public attention.The source,transmission,and movement of hydrogen,characterization parameters,and test methods of HE,as well as the characteristics and path of HE fractures,are introduced.The mechanisms and modes of crack propagation of HE and hydrogen-induced delayed fracture are reviewed.The recent progress surrounding micro and macro typical fracture characteristics and the influencing factors of HE are discussed.Finally,methods for improving HE resistance can be summarized as follows:(1)reducing crystalline grain and inclusion sizes(oxides,sulfides,and titanium nitride),(2)controlling nano-precipitates(niobium carbide,titanium carbide,and composite precipitation),and(3)increasing residual austenite content under the reasonable tension strength of steel.
基金supported financially by National Science Foundation of China(Grant Nos.51234002,51504064,and 51474064)National Key Research and Development Program 2016YFB0300601+1 种基金China Postdoctoral Science Foundation 2016M591443the Fundamental Research Funds for the Central Universities N160704002,N160708001
文摘The precipitation behavior of nanometer-sized carbides in ferrite in Nb-V-bearing low-carbon steel was studied by electron microscopy and nanoindentation hardness measurements. The results indicated that interphase precipitation and random precipitation could occur simultaneously for the specimen isothermally treated at 700 ℃ for 60 min, while in other specimens, only random precipitation was observed. This phenomenon might be explained by mass balance criterion during the diffusional phase transformation. Nanohardness result indicated that the average hardness of the specimens isothermally held at 600 ℃ for 20 min was 3.87 GPa. For the specimen isothermally holding at 650 ℃ for 20 min, the average hardness was 4.10 GPa and the distribution of the nanohardness was in a narrower range compared with that of the specimen isothermal holding at 600 ℃ for 20 min. These implied that the carbides in the specimens isothermal treated at 650℃ were more uniformly dispersed, and the number density of the carbides was greater than that treated at 600 ℃. Using Ashby-Orowan model, the contribution of precipitation strengthening to yield strength was estimated to be 110 MPa for the specimen isothermally treated at the temperature of 650 ℃ for 20 min.
基金supported by the Major State Basic Research Development Program of China(No.2004CB619108) the Science Foundation of the Ministry of Education of China(No.NECT-04-0278)
文摘Carbon steel strips with different phosphorus and carbon contents were produced by using the twin roll strip casting process. Fine grains and dendrite structure were observed in high-P steels. Negative phosphorus segregation was found in strip cast high-P and high-C steels. For the steels with different carbon contents, phosphorus distribution in the thickness direction of the strip is obviously different. This is because solutes are redistributed in the melting pool and the phosphorus segregation rate is associated with the length of the mushy zone and the phosphorus solubility in different phases. Phosphorus as a solute in ferrite can lead to the higher hardness and strength with lower plastic propertyies.
基金This work was supported by the National Natural Science Foundation of China(U1860201 and 51904070)China Postdoctoral Science Foundation(2018M631804)the Fundamental Research Funds for the Central Universities(N170703005).
文摘The effect of inclusion-induced nucleation on hot-rolled steel base metal was evaluated in comparison with welding heataffected zone(HAZ).Microstructure and mechanical properties of hot-rolled low-carbon steel containing Ti–Ca oxide particles were studied.The results showed that inclusions in Ti–Ca deoxidized steel distributed dispersely and were effective for intragranular acicular ferrite nucleation.Under hot rolling and controlled cooling conditions,microstructure in steel base metal was significantly refined and mainly consisted of acicular ferrite and intragranular bainite,which exhibited higher strength and excellent toughness.The microstructural evolution behavior followed the process that acicular ferrite plates divided the austenite grain,intragranular bainite packets formed between interlocking acicular ferrite plates,and the remaining austenite decomposed into fine polygonal ferrite grains.The resultant complex microstructure improved the impact toughness significantly.By comparison,in HAZ microstructure,laminar grain boundary ferrite having similar crystallography orientation showed adverse effect on toughness.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51104045)
文摘Based on medium plate runout table ultra-fast cooling( UFC)-accelerated cooling equipment( ACC) system,a heat transfer coefficient model was constructed. Firstly,according to the measured data,heat transfer coefficients under different roll speed and water volume were calculated by using an inverse heat conduction method. Secondly,a monofactorial heat transfer coefficient calculation formula was obtained. Finally,the heat transfer coefficient model based on medium plate runout table UFC-ACC system was constructed by intercept function,slope function,interaction influence function and linear or nonlinear influencing factors. The precision of these models was validated by comparing model prediction value with measured data,and the results were in good agreement with practical needs,and the average deviation was less than 5%.
基金Item Sponsored by National Natural Science Foundation of China(51004037)
文摘By measuring the expansion curves of a C-Mn steel at different cooling rates by using an MMS-300 thermo- mechanical simulator, continuous cooling transformation curves were obtained. The new process ＂ultra fast cooling＋ laminar cooling＂ was simulated and the effects of ultra fast cooling ending temperature on microstructure had also been investigated. The hot rolling experiment was done by adopting ＂high temperature rolling-[-forepart ultra fast cooling＂ technologies at laboratory scale. The results revealed that ultra fast cooling can delay the decrease of disloca- tion density and refine ferrite grains. Diversity control of the microstructure and phase transformation strengthening can be realized by changing the ultra fast cooling ending temperature. With the decrease of ultra fast cooling ending temperature, the strength and toughness increase, but plasticity does not decrease obviously. The new technique can improve the yield strength by over 50 MPa. Therefore, the upgrade of mechanical properties of C-Mn steel can be realized by using ＂high temperature rolling＋ ultra fast cooling＋laminar cooling＂ technique. Compared with ＂low temperature rolling with large deformation degree＂ technique, this new technology can decrease the roiling force and in- crease the production efficiency.
基金Supported by Youth Program of Xi'an Municipal Health Commission of China,No.2022qn07General Program of Xi'an Municipal Health Commission of China,No.2020ms14National Natural Science Foundation of China,No.81702067.
文摘BACKGROUND The gut microbiota(GM)has been proven to play a role in the regulation of host lipid metabolism,which provides a new theory about the pathogenesis of dyslipidemia.However,the associations of GM with dyslipidemia based on sex differences remain unclear and warrant elucidation.AIM To investigate the associations of GM features with serum lipid profiles based on sex differences in a Chinese population.METHODS This study ultimately recruited 142 participants(73 females and 69 males)at Honghui Hospital,Xi’an Jiaotong University.The anthropometric and blood metabolic parameters of all participants were measured.According to their serum lipid levels,female and male participants were classified into a high triglyceride(H_TG)group,a high total cholesterol(H_CHO)group,a low high-density lipoprotein cholesterol(L_HDL-C)group,and a control(CON)group with normal serum lipid levels.Fresh fecal samples were collected for 16S rRNA gene sequencing.UPARSE software,QIIME software,the RDP classifier and the FAPROTAX database were used for sequencing analyses.RESULTS The GM composition at the phylum level included Firmicutes and Bacteroidetes as the core GM.Different GM features were identified between females and males,and the associations between GM and serum lipid profiles were different in females and males.The GM features in different dyslipidemia subgroups changed in both female patients and male patients.Proteobacteria,Lactobacillaceae,Lactobacillus and Lactobacillus_salivarius were enriched in H_CHO females compared with CON females,while Coriobacteriia were enriched in L_HDL-C females.In the comparison among the three dyslipidemia subgroups in females,Lactobacillus_salivarius were enriched in H_CHO females,and Prevotellaceae were enriched in L_HDL-C females.Compared with CON or H_TG males,Prevotellaceae,unidentified_Ruminococcaceae,Roseburia and Roseburia_inulinivorans were decreased in L_HDL-C males(P value<0.05),and linear discriminant analysis effect size analysis indicated an enrichment of the above GM taxa in H_TG males compared with other male subgroups.Additionally,Roseburia_inulinivorans abundance was positively correlated with serum TG and total cholesterol levels,and Roseburia were positively correlated with serum TG level.Furthermore,Proteobacteria(0.724,95%CI:0.567-0.849),Lactobacillaceae(0.703,95%CI:0.544-0.832),Lactobacillus(0.705,95%CI:0.547-0.834)and Lactobacillus_salivarius(0.706,95%CI:0.548-0.835)could distinguish H_CHO females from CON females,while Coriobacteriia(0.710,95%CI:0.547-0.841),Coriobacteriales(0.710,95%CI:0.547-0.841),Prevotellaceae(0.697,95%CI:0.534-0.830),Roseburia(0.697,95%CI:0.534-0.830)and Roseburia_inulinivorans(0.684,95%CI:0.520-0.820)could discriminate H_TG males from CON males.Based on the predictions of GM metabolic capabilities with the FAPROTAX database,a total of 51 functional assignments were obtained in females,while 38 were obtained in males.This functional prediction suggested that cellulolysis increased in L_HDL-C females compared with CON females,but decreased in L_HDL-C males compared with CON males.CONCLUSION This study indicates associations of GM with serum lipid profiles,supporting the notion that GM dysbiosis may participate in the pathogenesis of dyslipidemia,and sex differences should be considered.
基金inancially supported by the National Natural Science Foundation of China(Nos.51174059,51404155,and U1260204)the Fundamental Research Funds for the Central Universities(N130407003)+1 种基金the Program for New Century Excellent Talents in University(NCET-130111)the Program for Liaoning Excellent Talents in University (LR2014007)
文摘Grain-oriented 4.5 wt% Si and 6.5 wt% Si steels were produced by strip casting, warm rolling, cold rolling, primary annealing, and secondary annealing. Goss grains were sufficiently developed and covered the entire surface of the secondary recrystallized sheets. The microstructure and texture was characterized by OM, EBSD, TEM, and XRD. It was observed that after rolling at 700 ℃, the 6.5 wt% Si steel exhibited a considerable degree of shear bands, whereas the 4.5 wt% Si steel indicated their rare presence. After primary annealing, completely equiaxed grains showing strong y-fiber texture were presented in both alloys. By comparison, the 6.5 wt% Si steel showed smaller grain size and few favorable Goss grains. Additionally, a higher density of fine precipitates were exhibited in the 6.5 wt% Si steel, leading to a ~ 30-s delay in primary recrystallization. During secondary annealing, abnormal grain growth of the 6.5 wt% Si steel occurred at higher temperature compared to the 4.5 wt% Si steel, and the final grain size of the 6.5 wt% Si steel was greater. The magnetic induction B8 of the 4.5 wt% Si and the 6.5 wt% Si steels was 1.75 and 1.76 T, respectively, and the high- frequency core losses were significantly improved in comparison with the non-oriented high silicon steel.
基金support from the National Natural Science Foundation of China (No. 51504063)
文摘In this study, the effect of cooling rates on microstructures and mechanical properties in a Al-bearing hot-rolled transformation- induced plasticity steel was investigated. The experiments were carried out using hot simulation machine and hot rolling mill, where the samples were cooled at different cooling rates. The results showed that with the increase in cooling rates, film-like retained austenite gradually disappeared and only blocky retained austenite was retained at higher cooling rates. The volume fraction of retained austenite was 9-11% at cooling rates of 0.05-1 ℃/s and 4-6% at cooling rates of 5-10 ℃/s. In addition, martensite/austenite island was observed because of the heterogeneous carbon distribution. The samples cooled at 0.05℃/s and 0.5 ℃/s exhibited excellent mechanical properties, with tensile strengths of 712 MPa and 726 MPa, total elongations of 42% and 36% and strength and ductility balances of 29.91 GPa% and 26.15 GPa%, respectively. During plastic deformation, the instantaneous work hardening exponent of the sample cooled at 0.05 ℃/s increased continuously until it reached the maximum value, while the instantaneous work hardening exponent of the sample cooled at 0.5℃/s remained stable.
