Multistage heat treatment involving quenching(Q),lamellarizing(L),and tempering(T)is applied to marine 10Ni5CrMoV steel.The microstructure and mechanical properties were studied by multiscale characterizations,and the...Multistage heat treatment involving quenching(Q),lamellarizing(L),and tempering(T)is applied to marine 10Ni5CrMoV steel.The microstructure and mechanical properties were studied by multiscale characterizations,and the kinetics of reverse austenite transformation,strain hardening behavior,and toughening mechanism were further investigated.The lamellarized specimens possess low yield strength but high toughness,especially cryogenic toughness.Lamellarization leads to the development of film-like reversed austenite at the martensite block and lath boundaries,refining the martensite structure and lowering the equivalent grain size.Kinetic analysis of austenite reversion based on the JMAK model shows that the isothermal transformation is dominated by the growth of reversed austenite,and the maximum transformation of reversed austenite is reached at the peak temperature(750℃).The strain hardening behavior based on the modified Crussard-Jaoul analysis indicates that the reversed austenite obtained from lamellarization reduces the proportion of martensite,significantly hindering crack propagation via martensitic transformation during the deformation.As a consequence,the QLT specimens exhibit high machinability and low yield strength.Compared with the QT specimen,the ductile-brittle transition temperature of the QLT specimens decreases from-116 to-130℃due to the low equivalent grain size and reversed austenite,which increases the cleavage force required for crack propagation and absorbs the energy of external load,respectively.This work provides an idea to improve the cryogenic toughness of marine 10Ni5CrMoV steel and lays a theoretical foundation for its industrial application and comprehensive performance improvement.展开更多
文摘目的探究血清瓜氨酸组蛋白H3(citrullinated histone H3,CitH3)、降钙素原(procalcitonin,PCT)及白细胞介素-10(interleukin-10,IL-10)对体外心肺复苏(extracorporeal cardiopulmonary resuscitation,ECPR)后急性肺损伤(acute lung injury,ALI)的预测价值。方法择取2021年1月至2024年4月行ECPR的患者126例,入院次日空腹采血测定患者血清CitH3、PCT、IL⁃10水平。根据ECPR后ALI发生与否分为ALI组与非ALI组,对比两组临床资料及血清CitH3、PCT、IL-10水平,Logistic多因素回归分析ECPR后ALI发生的危险因素。另外受试者工作特征(receive operating characteristic,ROC)曲线分析血清CitH3、PCT、IL-10对ALI的预测价值。结果因6例患者未配合完成相关检查等被剔除,最终纳入120例患者,其中住院期间ALI发生28例(ALI组),ALI未发生92例(非ALI组)。ALI组入院时急性生理学和慢性健康状况评分(Acute Physiology and Chronic Health Scoring System,APACHEⅡ)、序贯器官衰竭评估(Sequential Organ Failure Assessment,SOFA)、心肺复苏到自主循环恢复时间均大于非ALI组(P<0.05);ALI组血清CitH3、PCT、IL-10水平均高于非ALI组(P<0.05)。Logistic多因素回归分析显示心肺复苏到自主循环恢复时间、血清CitH3、PCT及IL-10是ALI发生的独立危险因素(P<0.05)。ROC曲线显示,血清CitH3、PCT、IL-10单一及3项联合预测ALI发生的曲线下面积(area under curve,AUC)分别为0.886、0.837、0.852、0.951,3项联合的AUC均大于PCT、IL-10单一检测(P<0.05)。结论ECPR后ALI发生患者血清CitH3、PCT、IL-10水平上升,对ALI发生有一定的预测价值,特别是联合检测效能更显著。
基金financially supported by the National Key K&D Program of China(No.2023YFE0200300)the National Natural Science Foundation of China(Nos.52174303and 51874084)the Program of Introducing Talents of Discipline to Universities(No.B21001)。
文摘Multistage heat treatment involving quenching(Q),lamellarizing(L),and tempering(T)is applied to marine 10Ni5CrMoV steel.The microstructure and mechanical properties were studied by multiscale characterizations,and the kinetics of reverse austenite transformation,strain hardening behavior,and toughening mechanism were further investigated.The lamellarized specimens possess low yield strength but high toughness,especially cryogenic toughness.Lamellarization leads to the development of film-like reversed austenite at the martensite block and lath boundaries,refining the martensite structure and lowering the equivalent grain size.Kinetic analysis of austenite reversion based on the JMAK model shows that the isothermal transformation is dominated by the growth of reversed austenite,and the maximum transformation of reversed austenite is reached at the peak temperature(750℃).The strain hardening behavior based on the modified Crussard-Jaoul analysis indicates that the reversed austenite obtained from lamellarization reduces the proportion of martensite,significantly hindering crack propagation via martensitic transformation during the deformation.As a consequence,the QLT specimens exhibit high machinability and low yield strength.Compared with the QT specimen,the ductile-brittle transition temperature of the QLT specimens decreases from-116 to-130℃due to the low equivalent grain size and reversed austenite,which increases the cleavage force required for crack propagation and absorbs the energy of external load,respectively.This work provides an idea to improve the cryogenic toughness of marine 10Ni5CrMoV steel and lays a theoretical foundation for its industrial application and comprehensive performance improvement.
