摘要
分别采用连续退火和水淬+回火工艺模拟了1000MPa级冷轧双相钢的退火过程。连续退火工艺下双相钢的屈服强度较低,250℃过时效时屈服强度为472MPa;320℃过时效时屈服强度为454MPa。而水淬+回火工艺下双相钢的屈服强度较高,250℃回火时屈服强度为1083MPa;320℃回火时屈服强度为887MPa。金相分析显示:连续退火工艺下最终组织为铁素体、回火马氏体和未回火马氏体;而水淬+回火工艺下最终组织为铁素体和回火马氏体。研究发现连续退火工艺下终冷阶段仍存在马氏体相变,终冷阶段生成的马氏体未发生回火,会导致最终组织中存在较高的可动位错密度和较大的内应力,这是连续退火工艺比水淬+回火工艺获得更低屈服强度的主要原因。
The annealing of 1000MPa cold rolled dual phase （DP） steel based on continuous annealing and water quenching（WQ） ＆ tempering processes was performed. The yield strength of the continu- ous annealing steels, which was very low, was 472MPa and 454MPa when overaging temperatures were 250℃ and 320℃, respectively. For the WQ ＆ tempering steels, when the tempering tempera- tures were 250℃ and 320℃, the yield strength was 1083MPa and 887MPa, respectively, and was much higher than that of the continuous annealing steels. The final microstructure constituents for the continuous annealing steels were ferrite, martensite and tempered martensite. But for the WQ ＆ tem- pering steels, ferrite and tempered martensite constituted the final microstructure. It＇s found that martensitic transformation also appeared during the final cooling stage in the continuous annealing processes. The martensite didn＇t undergo tempering and would result in higher dislocation density and internal stress in the DP steels. That is the main reason for the yield strength of the continuous annealing steels is lower than that of the WQ ＆ tempering steels.
出处
《材料工程》
EI
CAS
CSCD
北大核心
2012年第9期39-43,47,共6页
Journal of Materials Engineering
基金
国家高技术研究发展计划(863计划)资助项目(2009AA03Z518)
