The high-temperature dissolution behavior of carbides during the quenching process significantly influences grain growth,mechanical properties,and secondary carbide precipitation,thereby playing a major role in the he...The high-temperature dissolution behavior of carbides during the quenching process significantly influences grain growth,mechanical properties,and secondary carbide precipitation,thereby playing a major role in the heat treatment process of die steel.This study investigated the changes in carbide type,particle size distribution,and weight percentage in DC53 steel after holding at 1060℃for 2 h,followed by oil quenching.The analysis was conducted using Thermo-Calc,DICTRA computations,and experimental methods including electron backscatter diffraction,transmission electron microscopy and laser particle size analysis.The experimental results showed that four types of carbides(M_(7)C_(3),M_(6)C,M_(23)C_(6),and MC)existed in DC53 steel before quenching.After quenching,M_(23)C_(6)carbides were almost entirely dissolved,while the other three types partially dissolved into the matrix.The volume-weighted geometric mean size of carbides(x_(geo,3))increased from 5.43 to 15.15μm,and the weight percentage decreased from 13.03%to 5.01%.Small-sized carbides(below 5μm)dissolved more readily,which primarily accounted for the reduction in carbide weight percentage during quenching.In contrast,the weight percentage of large-sized carbides(greater than 10μm)varies less.DICTRA computations indicated that M_(7)C_(3)carbides smaller than 7μm can completely dissolve into the matrix after holding at 1060℃for 2 h.The findings provide an effective reference for optimizing carbide control during the heat treatment process of DC53 steel.展开更多
Objective With the increasing publication of clinical practice guidelines(CPG)for Traditional Chinese Medicine(TCM)and Integrated Traditional Chinese and Western Medicine(IM),the standardization and scientifiction of ...Objective With the increasing publication of clinical practice guidelines(CPG)for Traditional Chinese Medicine(TCM)and Integrated Traditional Chinese and Western Medicine(IM),the standardization and scientifiction of its formulation have gradually attracted many people’s attention.To offer an overview of TCM and IM CPGs published over the past decade and analyze their general characteristics and methodological quality.Methods The China National Knowledge Infrastructure(CNKI)and WANFANG databases were searched for clinical practice guidelines and expert consensus papers from January 2010 to June 2021.Two researchers independently completed the literature screening and cross-checking according to the inclusion and exclusion criteria of CPGs and extracted information on general characteristics and methodological quality of CPGs.Results According to the selection criteria,231 CPGs(EB-CPGs=119,CBCPGs=112)were selected and the number of CPGs published in the 11 years showed an overall upward trend.The vast majority of CPGs used the Western naming system for the diseases,and only 11 CPGs were named of TCM diseases or symptoms.TCM treatments were recommended in 223 CPGs.There were 156 ancient Chinese Medicine literature sources cited in 231 CPGs and opinions and experiences of 62 TCM experts cited in 37 CPGs.The methodological quality of EB-CPGs for TCM and IM were significantly better than CB-CPGs in 11 items.Only 60 EB-CPGs and 7 CB-CPGs designated clear criteria for grading quality of evidence and strength of the recommendations and 74 CPGs presented both the level of evidence and the strength of recommendations.We classified all CPGs according to whether or not they used GRADE,and the results showed that the CPGs using GRADE had higher methodological quality and more standardized reports.Conclusion This research has shown that the quantity and quality of CPGs in both TCM and IM have improved over the time span,but the methodological quality,especially evidence citation,and the use of criteria for grading quality of evidence and strength of the recommendations,still needs to further improvement in the future.展开更多
基金supported by the Central Guide Local Science and Technology Development Project of Hubei Province of China(No.2023EGA008)the Wuhan Natural Science Foundation Exploration Project(Chenguang Project,2024040801020309)。
文摘The high-temperature dissolution behavior of carbides during the quenching process significantly influences grain growth,mechanical properties,and secondary carbide precipitation,thereby playing a major role in the heat treatment process of die steel.This study investigated the changes in carbide type,particle size distribution,and weight percentage in DC53 steel after holding at 1060℃for 2 h,followed by oil quenching.The analysis was conducted using Thermo-Calc,DICTRA computations,and experimental methods including electron backscatter diffraction,transmission electron microscopy and laser particle size analysis.The experimental results showed that four types of carbides(M_(7)C_(3),M_(6)C,M_(23)C_(6),and MC)existed in DC53 steel before quenching.After quenching,M_(23)C_(6)carbides were almost entirely dissolved,while the other three types partially dissolved into the matrix.The volume-weighted geometric mean size of carbides(x_(geo,3))increased from 5.43 to 15.15μm,and the weight percentage decreased from 13.03%to 5.01%.Small-sized carbides(below 5μm)dissolved more readily,which primarily accounted for the reduction in carbide weight percentage during quenching.In contrast,the weight percentage of large-sized carbides(greater than 10μm)varies less.DICTRA computations indicated that M_(7)C_(3)carbides smaller than 7μm can completely dissolve into the matrix after holding at 1060℃for 2 h.The findings provide an effective reference for optimizing carbide control during the heat treatment process of DC53 steel.
基金This work was supported by the National Natural Science Foundation of China(No.82174230 and No.81904055).
文摘Objective With the increasing publication of clinical practice guidelines(CPG)for Traditional Chinese Medicine(TCM)and Integrated Traditional Chinese and Western Medicine(IM),the standardization and scientifiction of its formulation have gradually attracted many people’s attention.To offer an overview of TCM and IM CPGs published over the past decade and analyze their general characteristics and methodological quality.Methods The China National Knowledge Infrastructure(CNKI)and WANFANG databases were searched for clinical practice guidelines and expert consensus papers from January 2010 to June 2021.Two researchers independently completed the literature screening and cross-checking according to the inclusion and exclusion criteria of CPGs and extracted information on general characteristics and methodological quality of CPGs.Results According to the selection criteria,231 CPGs(EB-CPGs=119,CBCPGs=112)were selected and the number of CPGs published in the 11 years showed an overall upward trend.The vast majority of CPGs used the Western naming system for the diseases,and only 11 CPGs were named of TCM diseases or symptoms.TCM treatments were recommended in 223 CPGs.There were 156 ancient Chinese Medicine literature sources cited in 231 CPGs and opinions and experiences of 62 TCM experts cited in 37 CPGs.The methodological quality of EB-CPGs for TCM and IM were significantly better than CB-CPGs in 11 items.Only 60 EB-CPGs and 7 CB-CPGs designated clear criteria for grading quality of evidence and strength of the recommendations and 74 CPGs presented both the level of evidence and the strength of recommendations.We classified all CPGs according to whether or not they used GRADE,and the results showed that the CPGs using GRADE had higher methodological quality and more standardized reports.Conclusion This research has shown that the quantity and quality of CPGs in both TCM and IM have improved over the time span,but the methodological quality,especially evidence citation,and the use of criteria for grading quality of evidence and strength of the recommendations,still needs to further improvement in the future.
