镀锌钝化45A钢外套螺母及平管嘴腐蚀分析

Corrosion Analysis on Wrap Nut and Flat Mouthpiece of Galvanized Passivation 45A Steel

镀锌钝化的45A钢外套螺母和平管嘴,在机上装配使用一段时间后发现表面镀锌层色泽发暗、局部出现灰白色的腐蚀产物。通过宏观和微观形貌分析、能谱分析、金相检验,并结合零件的装配、试验流程分析,确定零件表面腐蚀是因气密试验中涂抹肥皂液未清洗所致。进一步的模拟验证试验结果表明:零件表面腐蚀程度与肥皂液残留的时间和浓度呈正相关,且高热、高湿的环境对腐蚀有促进作用。

Phenomenons of zinc coating surface color darkening and locally appearing grayish white corrosion products,were found on the surface of the galvanized passivation 45 Asteel wrap nut and flat mouthpiece after assembly and use for some time.Through macroscopic and microscopic morphology analysis,energy spectrum analysis,metallographic examination,combined with assembly and test process analysis of the parts,it is confirmed that the surface corrosion of the parts was caused by the uncleaning of the soap liquid in the airtight test.Further simulation test results show that the corrosion degree of the surface of the part was positively correlated with the residual time and concentration of the soap liquid,and the high heat and high humidity environment promoted the corrosion.