奥氏体化时间对I Q P工艺处理低碳硅锰钢组织和拉伸性能的影响

摘要

Intercritical annealing austenization &quenching &partitioning (I&Q&P)process was carried out on low carbon Si-Mn steel at different austenitizing times.The effects of austenitizing time on microstructure and tensile properties were investigated.The results show that the effect of Mn partitioning in intercritical zone was not eliminated by short time austenitizing;when the isothermal time was 300 s,the microstructure of tested steel at room temperature was lath martensite and retained austenite.As austenitizing time went on,the tensile strength of tested steel increased firstly and then decreased,and the max value was 1 267 MPa,but the elongation of tested steel decreased gradually.When the microstructure was just fully austenitic,austenite grain size was relatively small and the aggregation level of C and Mn partitioning was best,retained austenite content was the highest at this moment,TRIP effect was obvious during deformation,those can compensate for the decrease of the elongation. When the austenitizing time was 300 s,the tested steel had highest product of strength and elongation,the highest value was 30 345 MPa•%.%在不同奥氏体化时间下对低碳硅锰钢进行 I&Q&P 处理,研究了奥氏体化时间对试验钢组织与拉伸性能的影响。结果表明：短时间奥氏体化不能完全消除之前锰元素在双相区的配分结果；奥氏体化时间达到300 s 后,试验钢的室温组织为板条状马氏体和残余奥氏体；随奥氏体化时间延长,试验钢的抗拉强度先升高后降低,最高可达1267 MPa,但试验钢的伸长率则不断降低；刚完成完全奥氏体化时,晶粒尺寸较小,且碳、锰的聚集程度最佳,此时残余奥氏体的含量最高,形变过程中TRIP效应明显,使得伸长率的降低得以补偿；奥氏体化时间为300 s 时,试验钢的强塑积最高,可达30345 MPa•％。