铸铁同质焊材TIG焊接头组织与性能

Microstructure and Property of TIG Welding Cast Iron

以微合金化铸铁同质气焊丝为焊接材料,采用钨极氩弧焊对HT200铸铁件进行了焊接研究,分析了焊接区的组织和性能。结果表明,在室温焊接条件下,TIG焊缝组织由点球状和不规则碎块状石墨、少量鱼骨状的莱氏体及珠光体基体组成,熔合区组织由细小的点球状石墨、莱氏体和细密的柱晶基体组成。焊补区硬度值普遍高于铸件本体,可高出铸件本体ΔHB100之多。基于焊接过程中保护气体Ar对焊接区金属的激冷作用,TIG焊只可用于铸件非加工表面的焊补,而不宜用于有加工性能要求表面的修复。

Selecting micro-alloyed cast iron gas welding wire as welding materials, welding performance on HT200 grey cast iron by argon tungsten-arc welding was carried out to analyze its microstructure and property. Under the welding condition at room temperature, the experiment results show that the microstructures of TIG weld joint were made up of point-global and irregular broken blocky graphite, few herringbone ledeburite and pearlite matrix. And it contained fine pointglobal graphite, ledeburite and dense columnar grain matrix in the fusion zones. The value of hardness in the welding zones is 100 higher than that in the castings itself. Because of the chilling effect of Ar gas on the metals in the welding region during welding process, TIG welding can be used as weld repair in the non-machine surfaces of the castings, and it should not be used as weld repair for machine performance.