马氏体基TRIP钢的组织与力学性能

Microstructure and Mechanical Properties of TRIP-Aided Steel with Martensite Matrix

在基本C-Si-Mn系TRIP钢的基础上,通过调整工艺参数获得具有马氏体基的TRIP钢,通过扫描电镜分析、透射电镜分析、电子背散射衍射分析、X射线衍射分析、单向拉伸实验等对经不同工艺处理的实验用钢的显微组织和力学性能进行了对比分析.结果表明:两相区退火温度升高,铁素体比例减少,贝氏体比例增加,残余奥氏体整体先增加后减少;在较低温度下退火时,条状铁素体合并成为块状铁素体;在较高温度下退火时,条状奥氏体合并成为块状奥氏体,随后在冷却过程中转变为马氏体或残余奥氏体;实验钢在780℃退火时,获得最佳综合力学性能,此时抗拉强度达1053MPa,延伸率达23%,强塑积达24GPa×%.一定量的细小弥散的板条残余奥氏体是实验钢获得高强塑积的主要原因.

On the basis of C-Si-Mn TRIP-aided steel, a TRIP-aided steel with annealed martensite matrix was obtained by adjusting the process parameters. Then, the microstructure and mechanical properties of the steel obtained through different annealing processes were observed by means of SEM, TEM, electron backscatter diffraction, XRD, and uniaxial tensile test. The results indicate that （ 1 ） with the increase of intercritical annealing temperature, the proportion of ferrite reduces, while that of bainite increases, and the retained austenite proportion first increases and then decreases; （2） at low annealing temperature, strip ferrite merges into blocky ferrite, while at high annealing temperature, strip austenite merges into patches and then converts into martensite or retained austen- ite in the subsequent cooling process ; and （3） when the steel is annealed at 780℃, best comprehensive mechanical properties may be achieved, namely, a tensile strength of 1053 MPa, a total elongation of 23%, as well as a product of tensile strength and elongation of 4 GPa× %. Moreover, it is found that the existence of a certain amount of fine and dispersed lath retained austenite is the main cause of this high product of tensile strength and elongation.