An Fe-0.2C-1.5Si-1.67Mn steel was subjected to quenching and partitioning （Q＆P） process, and the interface migration between martensite and austenite at an elevated partitioning temperature was observed. The interf...An Fe-0.2C-1.5Si-1.67Mn steel was subjected to quenching and partitioning （Q＆P） process, and the interface migration between martensite and austenite at an elevated partitioning temperature was observed. The interface migration is excluded in constrained paraequilibrium （CPE） model. Based on ＂endpoint＂ predicted by CPE model the thermodynamic condition of interface migration is analyzed, that is, the difference in the chemical potential of iron in both ferrite （martenisite） and austenite produces the driving force of the iron atoms to migrate from one phase to the other phase. In addition, the interface migration can change the austenite fraction; as a result, the austenite fraction at partitioning temperature may be higher than that at quenching temperature through the interface migration, but this phenomenon cannot be explained by CPE model.展开更多
This study aims to investigate the effect of the 1-step quenching and partitioning （Q＆P） process on the microstructure and the resulting Vicker＇ s hardness of 0.3C-1.5Si-1.5Mn steel by using in-situ dilatometry ,o...This study aims to investigate the effect of the 1-step quenching and partitioning （Q＆P） process on the microstructure and the resulting Vicker＇ s hardness of 0.3C-1.5Si-1.5Mn steel by using in-situ dilatometry ,optical microscopy （ OM ）, scanning electron microscopy （ SEM ）, X-ray diffractometry （ XRD ）, and Vicker ＇ s hardness measurement. Systematic analyses indicate that the microstructure of the specimens quenched and partitioned at 150℃ ,200 ℃ ,250℃ ,and 300℃ mainly comprises lath martensite and retained austenite. The dilatometry curve of the specimen partitioned at 150℃ is presumably ascribed to the formation of isothermal martensite. In the early stages of partitioning at 200℃,the nearly unchanged dilatation curve is closely related to the synergistic effect of isothermal martensite formation and transitional epsilon carbide precipitation. In the later stages of partitioning at 200 ℃ ,the slight increase in the dilatation curve is due to the continuous isothermal martensite formation. With further increase in partitioning temperature to 250℃, the dilatation increases gradually up to 3600 s, which is related to carbon partitioning and lower bainite formation. Partitioning at a higher temperature of 300 ℃ causes a rapid increase in the dilatation curve during the initial stages, which subsequently levels off upon prolonging the partitioning time. This is mainly attributed to the rapid diffusion of carbon from athermal martensite to retained austenite and continuous formation of lower bainite.展开更多
采用盐浴炉对硅-锰系Q&P(quenching and partitioning)钢进行了Q&P工艺处理,研究了分配时间对热处理后试验钢显微组织、力学性能、残余奥氏体含量及残余奥氏体中碳含量的影响。结果表明:试验钢的显微组织为板条马氏体和残余奥氏...采用盐浴炉对硅-锰系Q&P(quenching and partitioning)钢进行了Q&P工艺处理,研究了分配时间对热处理后试验钢显微组织、力学性能、残余奥氏体含量及残余奥氏体中碳含量的影响。结果表明:试验钢的显微组织为板条马氏体和残余奥氏体,残余奥氏体以两种形态分布在不同位置,一种是以薄膜状分布在马氏体板条间,另一种是以块状分布在原奥氏体晶界处;在300℃的分配温度下进行较长时间保温能取得较好的强塑积,随着分配时间的延长,试验Q&P钢的残余奥氏体含量及残余奥氏体中的碳含量均不断增加,分配时间为1 200 s时所得试验钢的强塑积最高,可达37 300 MPa.%以上。展开更多
设计了一种中碳中锰Q&P(Quenching and partitioning)钢,基于热力学平衡理论计算分析了其相变过程,通过扫描电镜(SEM)、背散射电子衍射(EBSD)和透射电镜(TEM)研究了实验钢经不同热处理后的微观组织,测试了其力学性能,并采用X射线衍...设计了一种中碳中锰Q&P(Quenching and partitioning)钢,基于热力学平衡理论计算分析了其相变过程,通过扫描电镜(SEM)、背散射电子衍射(EBSD)和透射电镜(TEM)研究了实验钢经不同热处理后的微观组织,测试了其力学性能,并采用X射线衍射仪(XRD)进一步分析了拉伸断裂前后残留奥氏体含量的演变规律。结果表明:室温下实验钢微观组织为板条状马氏体和弥散分布的残留奥氏体;残留奥氏体主要存在于马氏体板条之间和原始奥氏体晶界处;随配分时间延长,抗拉强度逐渐降低,延伸率呈现升高趋势;试样拉断后,断口处残留奥氏体含量在3.5%~4.5%之间,明显低于拉伸前的含量(6.94%~10.78%),说明大部分残留奥氏体在拉伸过程中发生了TRIP效应,提高了实验钢的塑性。展开更多
主要对0.19C-1.52Si-1.53Mn-0.14Al-0.048Nb和0.19C-1.52Si-1.48Mn-0.15Al两种成分的钢进行了Q&P(quenching and partitioning)工艺处理,并研究二次淬火对Q&P钢组织性能的影响.结果表明:Nb的加入能够起到细晶强化和沉淀强化的效...主要对0.19C-1.52Si-1.53Mn-0.14Al-0.048Nb和0.19C-1.52Si-1.48Mn-0.15Al两种成分的钢进行了Q&P(quenching and partitioning)工艺处理,并研究二次淬火对Q&P钢组织性能的影响.结果表明:Nb的加入能够起到细晶强化和沉淀强化的效果,提高Q&P钢的综合性能.强塑积最高可达到25 190 MPa.%.二次淬火能够提高实验钢最终的马氏体含量,并大大提高钢的抗拉强度和屈服强度,降低了实验钢的应变硬化指数和总延伸率.若不采用二次淬火则会使实验钢的塑性大大提高,综合力学性能较高.展开更多
文摘An Fe-0.2C-1.5Si-1.67Mn steel was subjected to quenching and partitioning （Q＆P） process, and the interface migration between martensite and austenite at an elevated partitioning temperature was observed. The interface migration is excluded in constrained paraequilibrium （CPE） model. Based on ＂endpoint＂ predicted by CPE model the thermodynamic condition of interface migration is analyzed, that is, the difference in the chemical potential of iron in both ferrite （martenisite） and austenite produces the driving force of the iron atoms to migrate from one phase to the other phase. In addition, the interface migration can change the austenite fraction; as a result, the austenite fraction at partitioning temperature may be higher than that at quenching temperature through the interface migration, but this phenomenon cannot be explained by CPE model.
文摘This study aims to investigate the effect of the 1-step quenching and partitioning （Q＆P） process on the microstructure and the resulting Vicker＇ s hardness of 0.3C-1.5Si-1.5Mn steel by using in-situ dilatometry ,optical microscopy （ OM ）, scanning electron microscopy （ SEM ）, X-ray diffractometry （ XRD ）, and Vicker ＇ s hardness measurement. Systematic analyses indicate that the microstructure of the specimens quenched and partitioned at 150℃ ,200 ℃ ,250℃ ,and 300℃ mainly comprises lath martensite and retained austenite. The dilatometry curve of the specimen partitioned at 150℃ is presumably ascribed to the formation of isothermal martensite. In the early stages of partitioning at 200℃,the nearly unchanged dilatation curve is closely related to the synergistic effect of isothermal martensite formation and transitional epsilon carbide precipitation. In the later stages of partitioning at 200 ℃ ,the slight increase in the dilatation curve is due to the continuous isothermal martensite formation. With further increase in partitioning temperature to 250℃, the dilatation increases gradually up to 3600 s, which is related to carbon partitioning and lower bainite formation. Partitioning at a higher temperature of 300 ℃ causes a rapid increase in the dilatation curve during the initial stages, which subsequently levels off upon prolonging the partitioning time. This is mainly attributed to the rapid diffusion of carbon from athermal martensite to retained austenite and continuous formation of lower bainite.
文摘设计了一种中碳中锰Q&P(Quenching and partitioning)钢,基于热力学平衡理论计算分析了其相变过程,通过扫描电镜(SEM)、背散射电子衍射(EBSD)和透射电镜(TEM)研究了实验钢经不同热处理后的微观组织,测试了其力学性能,并采用X射线衍射仪(XRD)进一步分析了拉伸断裂前后残留奥氏体含量的演变规律。结果表明:室温下实验钢微观组织为板条状马氏体和弥散分布的残留奥氏体;残留奥氏体主要存在于马氏体板条之间和原始奥氏体晶界处;随配分时间延长,抗拉强度逐渐降低,延伸率呈现升高趋势;试样拉断后,断口处残留奥氏体含量在3.5%~4.5%之间,明显低于拉伸前的含量(6.94%~10.78%),说明大部分残留奥氏体在拉伸过程中发生了TRIP效应,提高了实验钢的塑性。
文摘主要对0.19C-1.52Si-1.53Mn-0.14Al-0.048Nb和0.19C-1.52Si-1.48Mn-0.15Al两种成分的钢进行了Q&P(quenching and partitioning)工艺处理,并研究二次淬火对Q&P钢组织性能的影响.结果表明:Nb的加入能够起到细晶强化和沉淀强化的效果,提高Q&P钢的综合性能.强塑积最高可达到25 190 MPa.%.二次淬火能够提高实验钢最终的马氏体含量,并大大提高钢的抗拉强度和屈服强度,降低了实验钢的应变硬化指数和总延伸率.若不采用二次淬火则会使实验钢的塑性大大提高,综合力学性能较高.
