The influence of rare earth metals and heat treatment on the microstructure and performance of M42 steel has been investigated by means of an optical microscope OM scanning electron microscope SEM energy dispersive sp...The influence of rare earth metals and heat treatment on the microstructure and performance of M42 steel has been investigated by means of an optical microscope OM scanning electron microscope SEM energy dispersive spectroscopy EDS transmission electron microscope TEM electron back-scatter diffraction EBSD and X-ray diffraction XRD . The results show that M2 C is the prevailing type of eutectic carbides in M42 steel. After modification with rare earth metals M2 C eutectic carbides change from the ordered lamellar structure into a circular structure.Despite different morphologies the two carbides present the same characteristics of microstructure and growth orientation.Compared with lamellar carbides M2 C carbides with the circular structure are much easier to decompose and spheroidize after heating which remarkably refines the carbide dimensions.The refined carbides improve the supersaturation of alloying elements in martensite and increase the hardness of M42 steel by 1.5 HRC.展开更多
For processing parts made from medium carbon steel, toughness and flexibility are of importance. There- fore, to achieve these properties, the cementite in the steels is spheroidized through heat treatment. Different ...For processing parts made from medium carbon steel, toughness and flexibility are of importance. There- fore, to achieve these properties, the cementite in the steels is spheroidized through heat treatment. Different parameters such as the time and temperature of spheroidizing and the initial microstructure of the steel affect the amount of spheroidized cementite. In the present work, the percent of contribution of two parameters, i.e. initial microstructure and spheroidizing time, to the percent of spheroidization in CK60 steel was investigated using Taguchi robust design. The initial microstructures consisted of martensite, coarse pearlite, fine pearlite and bainite and the chosen spheroidization times were 4, 8, 12, and 16h. Spheroidizing was done at the constant temperature 700℃. After spheroidizing was completed, the samples were prepared in order to observe their microstructure under an optical microscope and to determine the spheroidized percent using MIPTM （metallographic image processing） software. It was found that the spheroidizing time had the most influence （58.5 ~//0） on spheroidized percent and the initial microstructure only had a 31.1% contribution. Finally, the instantaneous growth rate of the carbide was also deduced.展开更多
A new spheroidizing process of ultra-high carbon steel （UHCS） containing C 1.55%, Cr 1.45%, and Al 1.5% in mass percent has been proposed. The effect of processing parameters on the microstructure was analyzed. The ...A new spheroidizing process of ultra-high carbon steel （UHCS） containing C 1.55%, Cr 1.45%, and Al 1.5% in mass percent has been proposed. The effect of processing parameters on the microstructure was analyzed. The UHCS produced by this new process has a microstructure with recrystallized ferrite matrix and fine and uniform carbide particles. After this spheroidizing, the UHCS exhibits good mechanical properties at ambient temperature, for example σb= 1 100 MPa, σs =915 MPa, δ=8% and high ratio of σs/σb.展开更多
The low-strength and high-brittleness of AZ91 cast magnesium alloy mainly result from the coarse divorced eutectic phase. To solve these problems, the annealing treatment of AZ91 cast magnesium alloy was carried out a...The low-strength and high-brittleness of AZ91 cast magnesium alloy mainly result from the coarse divorced eutectic phase. To solve these problems, the annealing treatment of AZ91 cast magnesium alloy was carried out at 415 ℃ and held for 24 h in this study and the alloy was then slowly cooled to room temperature in furnace. The microstructures of the alloy were observed using a metallographic microscope, a transmission electron microscopy and an emission scanning electron microscopy, respectively. The phase analysis was performed using the X-ray diffraction, and the tensile test of the specimen at ambient temperature was performed on a material test machine. The results indicate that the coarse divorced eutectic phase dissolves into the Mg matrix during the isothermal process, and the lamellarβ-Mg17AI12 phase precipitates from the magnesium solid solution with a type of pearlite precipitation during furnace cooling. Consequently, the spheroidizing treatment was carried out at 320℃ for 20 h following the annealing process and the lamellar β-Mg17A12 phase was spheroidized. Compared with the as-cast alloy, the strength and ductility of the AZ91 magnesium alloy are increased obviously after annealing treatment; the yield strength and tensile strength are increased to 137.8 MPa and 240.4 MPa from 102.9 MPa and 199.3 MPa, respectively; and the elongation is improved to 6.12% from 4.35%. After being spheroidized, the strength and hardness decrease a little, but the ductility is elevated to 7.23%. The nucleation, growth and spheroidizing mechanism of the lamellarβ-Mg12TAI12 phase were also discussed.展开更多
The influences of Ce, K and Na on the structures and properties of Fe-W-C alloy were investigated, and the idea estimating spheroidizing effect of carbides using circular degree(C.D) was put forward. The result shows ...The influences of Ce, K and Na on the structures and properties of Fe-W-C alloy were investigated, and the idea estimating spheroidizing effect of carbides using circular degree(C.D) was put forward. The result shows that eutectic carbide turns into sphericity from network after modification, carbide is refined and uniformly distributed and C.D of eutectic carbide increases. The mechanism of carbide spheroidizing was analyzed. The impact toughness and abrasion resistance of Fe-W-C obviously improve with the rise of C.D of carbides. The service life of modified Fe-W-C roll is 30% higher than that of high chromium cast iron roll, while its production cost is reduced by 30%.展开更多
The spheroidizing mechanism of W-phase in the Mg–Zn–Y–Mn–（B） alloys during solid-solution treatment was investigated by using kinetic methodologies. The microstructure and mechanical properties of heat-treated ...The spheroidizing mechanism of W-phase in the Mg–Zn–Y–Mn–（B） alloys during solid-solution treatment was investigated by using kinetic methodologies. The microstructure and mechanical properties of heat-treated Mg_（94）Zn_（2.5）-Y_（2.5）Mn_1 alloy containing 0.003 wt% B were compared with heat-treated Mg_（94）Zn_（2.5）-Y_（2.5）Mn_1 alloy. The heat-treated Mg_（94）Zn_（2.5）-Y_（2.5）Mn_1 alloy with 0.003 wt% B contained fine and uniform W-phase particles, which exhibited optimal mechanical performance. The ultimate tensile strength, yield strength and elongation were 287.7, 125.5 MPa and 21.1%,respectively.展开更多
Arrhythmogenic right ventricular cardiomyopathy(ARVC)is a progressive disease characterized by adipose and fibrous replacement of the myocardium.While elevated testosterone levels have been implicated in the pathologi...Arrhythmogenic right ventricular cardiomyopathy(ARVC)is a progressive disease characterized by adipose and fibrous replacement of the myocardium.While elevated testosterone levels have been implicated in the pathological process of ARVC,its exact contribution to cardiac fibrosis in ARVC remains unclear.In this study,we analyzed the potential contribution of gender-based differences on the distribution of the low-voltage area in an ARVC cohort undergoing an electrophysiological study,which was indicated by feature selection.Additionally,we established engineered cardiac spheroid models in vitro using patient-specific induced pluripotent stem cell(iPSC)-derived cardiomyocytes(iPSC-CMs)and iPSC-derived cardiac fibroblasts(icFBs).We elucidated the pathogenicity of abnormal splicing in the plakophilin-2(PKP2)gene caused by an intronic mutation.Additionally,pathogenic validation of the desmoglein-2(DSG2)point mutation further confirms the reliability of the models.Moreover,testosterone exacerbated the DNA damage in the mutated cardiomyocytes and further activated myofibroblasts in a chain reaction.In conclusion,we designed and constructed an in vitro three-dimensionally-engineered cardiac spheroid model of ARVC based on clinical findings and provided direct evidence of the fibrotic role of testosterone in ARVC.展开更多
Liposarcoma is one of the most common soft tissue sarcomas,however,its occurrence rate is still rare compared to other cancers.Due to its rarity,in vitro experiments are an essential approach to elucidate liposarcoma ...Liposarcoma is one of the most common soft tissue sarcomas,however,its occurrence rate is still rare compared to other cancers.Due to its rarity,in vitro experiments are an essential approach to elucidate liposarcoma pathobiology.Conventional cell culture-based research(2D cell culture)is still playing a pivotal role,while several shortcomings have been recently under discussion.In vivo,mouse models are usually adopted for pre-clinical analyses with expectations to overcome the issues of 2D cell culture.However,they do not fully recapitulate human dedifferentiated liposarcoma(DDLPS)characteristics.Therefore,three-dimensional(3D)culture systems have been the recent research focus in the cell biology field with the expectation to overcome at the same time the disadvantages of 2D cell culture and in vivo animal models and fill in the gap between them.Given the liposarcoma rarity,we believe that 3D cell culture techniques,including 3D cell cultures/co-cultures,and Patient-Derived tumor Organoids(PDOs),represent a promising approach to facilitate liposarcoma investigation and elucidate its molecular mechanisms and effective therapy development.In this review,we first provide a general overview of 3D cell cultures compared to 2D cell cultures.We then focus on one of the recent 3D cell culture applications,Patient-Derived Organoids(PDOs),summarizing and discussing several PDO methodologies.Finally,we discuss the current and future applications of PDOs to sarcoma,particularly in the field of liposarcoma.展开更多
基金The National Natural Science Foundation of China(No.51301038,51201031,51371050)the Industry-AcademiaResearch Cooperative Innovation Fund of Jiangsu Province(No.BY2014127-03)+1 种基金the Natural Science Foundation of Jiangsu Province(No.BK20141306)the Scientific and Technological Innovation Fund of Danyang(No.SY201305)
文摘The influence of rare earth metals and heat treatment on the microstructure and performance of M42 steel has been investigated by means of an optical microscope OM scanning electron microscope SEM energy dispersive spectroscopy EDS transmission electron microscope TEM electron back-scatter diffraction EBSD and X-ray diffraction XRD . The results show that M2 C is the prevailing type of eutectic carbides in M42 steel. After modification with rare earth metals M2 C eutectic carbides change from the ordered lamellar structure into a circular structure.Despite different morphologies the two carbides present the same characteristics of microstructure and growth orientation.Compared with lamellar carbides M2 C carbides with the circular structure are much easier to decompose and spheroidize after heating which remarkably refines the carbide dimensions.The refined carbides improve the supersaturation of alloying elements in martensite and increase the hardness of M42 steel by 1.5 HRC.
文摘For processing parts made from medium carbon steel, toughness and flexibility are of importance. There- fore, to achieve these properties, the cementite in the steels is spheroidized through heat treatment. Different parameters such as the time and temperature of spheroidizing and the initial microstructure of the steel affect the amount of spheroidized cementite. In the present work, the percent of contribution of two parameters, i.e. initial microstructure and spheroidizing time, to the percent of spheroidization in CK60 steel was investigated using Taguchi robust design. The initial microstructures consisted of martensite, coarse pearlite, fine pearlite and bainite and the chosen spheroidization times were 4, 8, 12, and 16h. Spheroidizing was done at the constant temperature 700℃. After spheroidizing was completed, the samples were prepared in order to observe their microstructure under an optical microscope and to determine the spheroidized percent using MIPTM （metallographic image processing） software. It was found that the spheroidizing time had the most influence （58.5 ~//0） on spheroidized percent and the initial microstructure only had a 31.1% contribution. Finally, the instantaneous growth rate of the carbide was also deduced.
基金Item Sponsored by Provincial Natural Science Foundation of Hebei Province of China (500023)
文摘A new spheroidizing process of ultra-high carbon steel （UHCS） containing C 1.55%, Cr 1.45%, and Al 1.5% in mass percent has been proposed. The effect of processing parameters on the microstructure was analyzed. The UHCS produced by this new process has a microstructure with recrystallized ferrite matrix and fine and uniform carbide particles. After this spheroidizing, the UHCS exhibits good mechanical properties at ambient temperature, for example σb= 1 100 MPa, σs =915 MPa, δ=8% and high ratio of σs/σb.
基金supported by the National Science&Technology Pillar Program of China(Grant No.2006BAE04B05-1)the Natural Science Foundation of Shanxi Province(Grant No.2012JQ6020)the Doctor Foundation of Xian University of Science & Technology of China(2011QDJ017)
文摘The low-strength and high-brittleness of AZ91 cast magnesium alloy mainly result from the coarse divorced eutectic phase. To solve these problems, the annealing treatment of AZ91 cast magnesium alloy was carried out at 415 ℃ and held for 24 h in this study and the alloy was then slowly cooled to room temperature in furnace. The microstructures of the alloy were observed using a metallographic microscope, a transmission electron microscopy and an emission scanning electron microscopy, respectively. The phase analysis was performed using the X-ray diffraction, and the tensile test of the specimen at ambient temperature was performed on a material test machine. The results indicate that the coarse divorced eutectic phase dissolves into the Mg matrix during the isothermal process, and the lamellarβ-Mg17AI12 phase precipitates from the magnesium solid solution with a type of pearlite precipitation during furnace cooling. Consequently, the spheroidizing treatment was carried out at 320℃ for 20 h following the annealing process and the lamellar β-Mg17A12 phase was spheroidized. Compared with the as-cast alloy, the strength and ductility of the AZ91 magnesium alloy are increased obviously after annealing treatment; the yield strength and tensile strength are increased to 137.8 MPa and 240.4 MPa from 102.9 MPa and 199.3 MPa, respectively; and the elongation is improved to 6.12% from 4.35%. After being spheroidized, the strength and hardness decrease a little, but the ductility is elevated to 7.23%. The nucleation, growth and spheroidizing mechanism of the lamellarβ-Mg12TAI12 phase were also discussed.
文摘The influences of Ce, K and Na on the structures and properties of Fe-W-C alloy were investigated, and the idea estimating spheroidizing effect of carbides using circular degree(C.D) was put forward. The result shows that eutectic carbide turns into sphericity from network after modification, carbide is refined and uniformly distributed and C.D of eutectic carbide increases. The mechanism of carbide spheroidizing was analyzed. The impact toughness and abrasion resistance of Fe-W-C obviously improve with the rise of C.D of carbides. The service life of modified Fe-W-C roll is 30% higher than that of high chromium cast iron roll, while its production cost is reduced by 30%.
基金support from the National Natural Science Foundation of China(Nos.51474153 and 51574175)Ph.D.Programs Foundation of Ministry of Education of the People’s Republic of China(No.20111402110004)Natural Science Foundation of Shanxi Province(Nos.2009011028-3 and 2012011022-1)
文摘The spheroidizing mechanism of W-phase in the Mg–Zn–Y–Mn–（B） alloys during solid-solution treatment was investigated by using kinetic methodologies. The microstructure and mechanical properties of heat-treated Mg_（94）Zn_（2.5）-Y_（2.5）Mn_1 alloy containing 0.003 wt% B were compared with heat-treated Mg_（94）Zn_（2.5）-Y_（2.5）Mn_1 alloy. The heat-treated Mg_（94）Zn_（2.5）-Y_（2.5）Mn_1 alloy with 0.003 wt% B contained fine and uniform W-phase particles, which exhibited optimal mechanical performance. The ultimate tensile strength, yield strength and elongation were 287.7, 125.5 MPa and 21.1%,respectively.
基金supported by the National Natural Science Foundation of China(Nos.82370322 to CC,82200352 to FZ,82300352 to YZ,22275034 to HX,and 82070343 to MLC)the Natural Science Foundation of Jiangsu Province of China(Nos.BK20220710 to FZ and BK20230733 to YZ)Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.JX13414086 to HYC).
文摘Arrhythmogenic right ventricular cardiomyopathy(ARVC)is a progressive disease characterized by adipose and fibrous replacement of the myocardium.While elevated testosterone levels have been implicated in the pathological process of ARVC,its exact contribution to cardiac fibrosis in ARVC remains unclear.In this study,we analyzed the potential contribution of gender-based differences on the distribution of the low-voltage area in an ARVC cohort undergoing an electrophysiological study,which was indicated by feature selection.Additionally,we established engineered cardiac spheroid models in vitro using patient-specific induced pluripotent stem cell(iPSC)-derived cardiomyocytes(iPSC-CMs)and iPSC-derived cardiac fibroblasts(icFBs).We elucidated the pathogenicity of abnormal splicing in the plakophilin-2(PKP2)gene caused by an intronic mutation.Additionally,pathogenic validation of the desmoglein-2(DSG2)point mutation further confirms the reliability of the models.Moreover,testosterone exacerbated the DNA damage in the mutated cardiomyocytes and further activated myofibroblasts in a chain reaction.In conclusion,we designed and constructed an in vitro three-dimensionally-engineered cardiac spheroid model of ARVC based on clinical findings and provided direct evidence of the fibrotic role of testosterone in ARVC.
文摘Liposarcoma is one of the most common soft tissue sarcomas,however,its occurrence rate is still rare compared to other cancers.Due to its rarity,in vitro experiments are an essential approach to elucidate liposarcoma pathobiology.Conventional cell culture-based research(2D cell culture)is still playing a pivotal role,while several shortcomings have been recently under discussion.In vivo,mouse models are usually adopted for pre-clinical analyses with expectations to overcome the issues of 2D cell culture.However,they do not fully recapitulate human dedifferentiated liposarcoma(DDLPS)characteristics.Therefore,three-dimensional(3D)culture systems have been the recent research focus in the cell biology field with the expectation to overcome at the same time the disadvantages of 2D cell culture and in vivo animal models and fill in the gap between them.Given the liposarcoma rarity,we believe that 3D cell culture techniques,including 3D cell cultures/co-cultures,and Patient-Derived tumor Organoids(PDOs),represent a promising approach to facilitate liposarcoma investigation and elucidate its molecular mechanisms and effective therapy development.In this review,we first provide a general overview of 3D cell cultures compared to 2D cell cultures.We then focus on one of the recent 3D cell culture applications,Patient-Derived Organoids(PDOs),summarizing and discussing several PDO methodologies.Finally,we discuss the current and future applications of PDOs to sarcoma,particularly in the field of liposarcoma.
