高频电阻焊连续油管焊接HAZ组织性能热模拟分析

Thermal simulation analysis of HAZ microstructure and properties of coiled tubing welding by high frequency resistance welding

采用热模拟技术、显微分析方法和力学性能测试等手段,对连续油管用粒状贝氏体钢在高频电阻焊接过程中接头热影响区不同部位的微观组织和宏观力学性能进行分析。通过与母材组织及力学性能的对比表明,在接头热影响区中,过热粗晶区以长条状铁素体组织为主,断口形貌以均匀的韧窝为主,韧窝大且深,韧性较好,冲击功值相对较高。正火区和不完全正火区组织以多边形铁素体为主,晶粒之间晶界清晰,断口以准解理断裂为主,冲击吸收功值较低;回火区没有发生明显相变,晶粒尺寸比母材的略有增大,组织发生了微小的回复再结晶,材料的冲击吸收功值有所回复。

By means of thermal simulation technique,microscopic analysis method and macro mechanical property testing,the microstructure and mechanical properties at different locations within heat-affected zone(HAZ) of the joint during the high frequency resistance welding of granular bainite steel for coiled tubing welding was analyzed.At the same time,compared with the microstructure and mechanical properties of base material,the results showed that within the heat-affected zone of the joint,the overheated coarse grain zone was mainly composed of strip ferrite microstructure,fracture surface was mainly composed of uniform dimple,which were broad and deep,with better toughness and relatively higher impact energy value.The normalized and not fully normalized areas were mainly composed of polygonal ferrite,the grain boundary between grains was clear,fracture surface was mainly quasi-cleavage fracture,and the impact energy was relatively low.There was no obvious phase change in the tempering area,the grain size was slightly increased compared with that of the base material,and of temper zone was increased slightly than the base material,recovery and re-crystallization was generated in the microstructure,and the material impact energy values rised slightly.