“原位观察”下的水龙头激光焊接头腐蚀性能分析

Analysis of corrosion performance of laser welded joint of tap based on in-situ tracking method

采用低耗能激光焊新工艺制造水龙头薄壳,替代传统高污染、高耗能的整体铸造工艺,对304、310 s不锈钢激光焊接头进行沸腾硫酸-硫酸铁及室温浸蚀对比腐蚀研究.在设定的腐蚀时间内,采用"原位观察"腐蚀过程焊缝及熔合区微观组织变化.结果表明,310 s比304耐腐蚀性更好,随腐蚀时间加长,接头熔合区晶粒晶界未明显加宽,焊缝断口微观特征主要为韧窝,证明其未发生晶间腐蚀.焊缝金属成分分析表明焊缝中心晶粒与母材相近,腐蚀沟Cr元素降至20.81%高于12%,保证其耐腐蚀性能.

The thin-shell tap was fabricated using new process of low-energy laser welding,instead of the traditional casting process which had high pollution and high energy-consuming. The corrosion resistance of the 304 and 310 s stainless steel was investigated in boiling sulfuric acid and acid at room temperature,respectively. The microstructure of weld beam and fusion zone during corrosion process was observed by in-situ tracking method. The results showed that corrosion resistance of310 s stainless steel is better than that of 304 stainless steel.With the time increasing,grain boundaries of the fusion line do not widen obviously. Microscopic features of the fracture were dimples,which is indirect proof for its good corrosion resistance.Analysis indicated the chemical compositions in weld metal are close to that in the base metal. Cr content in corrosion ditch fell to 20. 81%,but still more than 12%,ensuring the excellent corrosion resistance.