退火工艺对1200MPa级TRIP钢的组织和力学性能的影响

Effect of annealing process on microstructure and mechanical properties of 1200 MPa high strength TRIP-aided steel

采用不同的退火工艺得到了多边形铁素体基TRIP钢(TPF)、贝氏体铁素体基TRIP钢(TBF)和回火马氏体基TRIP钢(TAM)3种不同基体结构的TRIP钢,并对它们的显微组织和力学性能进行研究。结果表明,退火工艺的不同导致实验钢的微观组织完全不同,力学性能也存在显著差异。TPF钢的基体结构为尺寸较大的多边形铁素体,其上分布着贝氏体、马氏体及少部分残留奥氏体,抗拉强度和伸长率均低于TBF钢与TAM钢。TBF钢的基体结构为贝氏体铁素体,残留奥氏体呈长条状或块状分布于贝氏体板条间,表现出高强度但伸长率不佳。TAM钢组织由退火马氏体基体、残留奥氏体及新生马氏体组成,残留奥氏体以稳定的长条状或薄膜状分布在退火马氏体晶界处或板条间,具有最佳的力学性能。

TRIP-aided steel with matrices of polygonal ferrite( TPF),bainitic ferrite( TBF) and tempered martensite( TAM) was obtained by different annealing processes,and their microstructure and mechanical properties were also studied. The results indicate that different annealing processes could result in completely different microstructure,and a significant difference in mechanical properties of the steel.The matrix of TPF steel is polygonal ferrite in coarse grain,with bainite and retained austenite-martensite islands distribution on it. The tensile strength and the total elongation of the TPF steel are lower than those of the TBF steel and the TAM steel. The matrix of TBF steel is bainitic ferrite,with blocky and lath-like retained austenite between the bainitic ferrite. TBF steel possesses high tensile strength with lower elongation. The microstructure of the TAM steel consists of tempered martensite matrix,with fresh martensite,and film-like retained austenite distributed at grain boundaries and between the tempered martensite laths. The TAM steel exhibits an excellent combination of strength and elongation.