逆相变退火中锰钢的组织性能与成形极限

分别通过SEM、XRD、单轴拉伸试验和FLD等方法对比研究了中锰钢(MMnS780钢)与DP780钢的微观组织、力学性能及成形极限。结果表明,DP780钢获得铁素体和马氏体双相组织,具有连续屈服及较大的加工硬化能力,而MMnS780钢由细小的铁素体和奥氏体构成,具有明显屈服、相对较小的加工硬化能力和较大的均匀伸长率;不同应变状态下MMnS780钢较DP780钢具有更高的极限应变。退火组织以及细小的晶粒尺寸使MMnS780钢产生明显的屈服现象,细小组织以及亚稳奥氏体的TRIP效应使其具有较高的塑性和成形性能。

Study on microstructure,mechanical properties and forming limit curve of ART annealed medium manganese steel

The microstructure, mechanical properties and forming limit curve of ART annealed medium manganese steel (MMnS780 steel) and DP780 steel were comparatively studied by scanning electron microscopy, X ray diffraction, uniaxial tensile test and forming limit diagram, respectively. The results show that DP780 steel obtains ferrite and martensite dual phase structure, and shows continuous yielding behavior and higher work hardening capacity, while MMnS780 steel is composed of small ferrite and austenite, which has a obvious yield plateau, relatively lower work hardening ability and larger uniform elongation. MMnS780 steel has higher ultimate strain than DP780 steel under different strain conditions. The annealed state and fine grain size make MMnS780 steel has the obvious yield plateau, and the transformation induced plasticity effect of fine microstructure and metastable austenite lead to higher ductility and formability.