淬火-配分(Quenching and Partitioning,Q&P)钢由于具有优异的综合性能而备受关注.本文设计了一步等温和二步等温处理工艺,通过改变淬火温度和等温温度获得了不同含量一次马氏体(PM)、残余奥氏体(RA)、二次马氏体(FM)及贝氏体(BF)的多相微观结构.采用XRD、EBSD综合分析了淬火配分处理对马氏体/贝氏体形态、位错密度、体积含量、变体选择行为以及冲击韧性的影响.示波冲击试验结果表明:330℃是一步淬火配分和二步淬火配分处理的最佳淬火温度,该温度能够获得最佳的冲击韧性.与一步淬火配分处理比较,二步淬火配分处理可以提高复相组织中的RA含量,并降低FM含量.最优的淬火温度和配分温度有利于降低马氏体/贝氏体(M/B)中的位错密度、增加RA和大角度晶界(HAGB)体积含量,从而显著改善Q&P钢的冲击韧性.
Effect of quenching and partitioning on the impact toughness of 30CrMnSiA steel
Quenching and partitioning(Q&P)steel has attracted much attention due to its excellent comprehensive properties.In this work,one step isothermal and two step isothermal treatment was designed.By changing the quenching temperature and isothermal temperature,different contents of primary martensite(PM),residual austenite(RA),secondary martensite(FM)and the heterogeneous microstructure of bainite(BF)were obtained.The effects of quenching isothermal treatment on martensite/bainite morphology,dislocation density,volume content and variant selection behavior on impact toughness were analyzed by XRD and EBSD.The results of oscilloscope impact test show that 330 ℃ is the optimal quenching temperature for one-step isothermal treatment and two-step isothermal treatment,as it provides the best impact toughness.Compared with one-step quenching isothermal treatment,two-step quenching isothermal treatment can increase RA content and reduce FM content in multiphase structure.The optimal quenching temperature and partitioning temperature can reduce the dislocation density in M/B and increase the volume content of RA and high-angle grain boundary(HAGB),which can significantly improve the impact toughness of Q&P steel.
万方数据
维普
