摘要
针对一种0.14C-2.72Mn-1.29Si冷轧高强钢进行了轧制和不同等温时效温度的退火处理,得到了两种不同退火基体的组织特征,均具有较好的综合力学性能。利用FESEM、XRD、TEM和拉伸试验对比分析了不同退火基体试验钢的微观组织、力学性能和加工硬化行为。研究表明:试验钢在220~300℃等温时效后钢板的基体组织主要由铁素体和马氏体构成,240℃等温时效后钢板的综合性能最佳,屈服强度为672 MPa,抗拉强度为1333 MPa,总伸长率为13%,屈强比为0.50,组织中含有5.75%的残留奥氏体。而试验钢在390~430℃等温时效后钢板的基体组织主要由铁素体和贝氏体构成,在390℃等温时效后钢板的综合性能最佳,屈服强度为505 MPa,抗拉强度为1115 MPa,总伸长率为17%,屈强比为0.45,组织中含有11.17%的残留奥氏体。铁素体+马氏体基体退火钢优异的综合力学性能主要源于细晶强韧化;而铁素体+贝氏体基体退火钢优异的性能主要源于细晶强韧化和TRIP效应增塑,这两种机制的共同作用,使得钢板在高强度的同时,还具有较好的塑韧性。
A 0. 14C-2. 72Mn-1. 29 Si cold rolling high strength steel was treated by cold rolling and annealing treatment at different isothermal aging temperatures,and different microstructure of the steel with good mechanical properties was obtained. Microstructure of the steel was characterized by FESEM,XRD and TEM,and its mechanical behavior was examined by tensile tests. Results show that the microstructure of the steel sheets consists of ferrite and martensite after isothermal aging at 220-300 ℃,and the best mechanical properties with yield strength of 672 MPa,tensile strength of 1333 MPa,and total elongation of 13% can be obtained for the steel sheets after aging at 240 ℃. The microstructure of ferrite bainite and larger amount of retained austenite is observed for the steel sheets after isothermal aging at 390-430℃,and steel sheets have a good combination of mechanical properties when aging at 390 ℃,with yield strength of505 MPa,tensile strength of 1115 MPa,and total elongation of 17%. Good properties of the tested steel with ferrite and martensite matrix microstructure are due to grain refinement. The good combination of the strength and plasticity of the steel with ferrite and bainite matrix is ascribed to grain refinement,and transformation induced plasticity( TRIP) effect.
引文
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