成套焊接工艺下贝氏体钢轨接头组织及性能研究

采用交叉试验的方法制备无碳化物贝氏体钢轨固定式闪光焊接头,对不同工艺条件下钢轨正向载荷敏感区域的金相组织进行观察分析,对贝氏体钢轨焊接过程中合金元素的迁移以及焊接缺陷的出现做出解释,并测定不同工艺条件下接头的拉伸、冲击、硬度性能。结果表明:不同工艺条件下焊缝过热区均由于合金元素迁移出现块状马氏体组织及带状组织;正火工艺后焊缝组织为仿晶界型先共析铁素体+粒状贝氏体相结构,拉伸、冲击性能均有提高,但过热区贝氏体局部重构导致白色微区、带状组织在过热区的体积百分数及分布范围增大;金相视野内焊后及正火后接头喷风工艺令白色微区、带状组织体积分布范围增大。

Study on Microstructures and Properties of Bainitic Rail Joints Under Complete Welding Process

Based on f ixed f lash welding joints of carbide-free bainitic rails prepared by the method of cross-over study,this paper observed and analyzed the metallographic structures in the positive load sensitive areas of the rails under different process conditions,and explained the migrations of alloy elements and the appearances of welding defects during the welding process of bainitic rails,then measured the tensile,impact and hardness properties of joints under different process conditions.The results show that,under different process conditions,massive martensite structures and banded structures appear in weld overheated zones due to alloy elements migration.After normalizing process,the weld microstructure is grain boundary-like proeutectoid ferrite+granular bainite phase structure,and the tensile and impact properties are improved,but the volume percentages and distribution ranges of white microzone and banded structure in overheating zone increase due to local bainite reconstruction.The joint blowing process after welding and normalizing in the metallographic f ield promotes the increase of the volume distribution range of white microzone and banded structure.