耐候钢热处理双相化组织与性能

研究了铁路机车车辆用的两种热轧耐候钢经热处理双相化的的金相组织及各种力学性能，结果表明，耐候钢双相化后的显微组织由多边形等轴铁素体晶粒和不规则岛状马氏体组成，且原始组织对其有很大影响；两种热轧耐候钢双相化热处理前后的显微镜组织和力学性能均无明显的各向异性，研究发现，双相化加热温度对马氏体含量，铁素体晶粒大小，屈服现象，屈服强度、抗拉强度、屈强比、伸长率及加工硬化指数（n值）等双相化钢的组织和性能均有显著影响，根据试验结果，确定的耐候钢最佳热处理双相比工艺为780℃加热，10％NaCl水溶液淬火，本研究成果将为进一步采用控制轧制法进行耐候双相钢的生产奠定基础。

Microstructures and Properties of Weathering Steels after Dual phase Heat Treatment

The microstructures and mechanical properties of two weathering steels used in railway rolling stocks after dual-phase heat treatment are studied.The metallographic testing results show that the microstructures of the weathering dual-phase steels consist of equiaxed polygonal ferrite matrix and island-shape martensite，the sizes and the morphology of which are greatly affected by the original microstructures of the two as-rolled steels，and that the microstructures of the steels are basically isotropic both before and after dual-phase treatment.It is found that the heating temperature in the dual-phase treatment has significant influences on microstructures and properties of the weathering dual-phase steels，such as the volume fraction of martensites，the yield behavior，the YS，the UTS，the ratio of YS to UTS，the elongation，the strain hardening coefficent（n value），etc.According to the results of the metallographic and mechanical tests，the optimum dual-phase heat treating process-quenching at 780℃ into the brine of 10％wt NaCl is finally determined.The achievments of this study will lay a foundation of the research on the production of the weathering dual-phase steels by controlled-hot-rolling process.