机车构架封闭角焊缝裂纹成因分析及改进

Analysis and improvement of the sealing fillet weld crack on locomotive framework

针对某机车构架在生产过程中,座板与上盖板之间的封闭角焊缝出现裂纹,对板材、焊丝、焊缝进行化学成分、力学性能检测,对焊缝裂纹进行焊缝和断口的宏观、微观分析等,研究裂纹的性质、产生的原因等,确定裂纹不是焊接产生的热裂纹或冷裂纹,而是由焊接前座板与上盖板之间存在的一定量高温时可气化的物质导致。针对裂纹原因提出控制焊材、焊缝及其附近母材的清洁度,在盖板上开排气孔等改进措施,经实施验证,能够有效防止裂纹的再发生。

Focusing on the cracks appeared at the sealing fillet weld between seat plate and cover plate in the process of a locomotive framework production,chemical composition analysis and mechanical property test of the plates,welding wire and weld is conducted,and macro analysis and microanalysis of the weld and fracture is carried out on the weld crack to probe into the nature and cause of the cracks.It’s decided that the cracks are not the hot cracks or cold cracks generated in welding operation,but caused by a certain amount of gasifiable matter between the seat plate and cover plate at high temperature before welding.On that account,this paper presents some improvement measures,including controlling the cleanliness of welding consumables,weld and adjacent base metal and cutting gas vent on the cover plate.It’s been proved that these measures can effectively prevent such cracks from occurring again.