表面状态对N06625镍基合金去应力热处理后腐蚀性能的影响

Effect of Surface State on Corrosion Resistance of N06625 Nickel-based Alloy after Stress Relief Heat Treatment

按照ASTM G28—2002(Reapproved 2015)《Standard Test Method for Detecting Susceptibility to Intergranular Corrosion in Wrought,Nickel-rich,Chromium-bearing Alloys》中方法A对供货态和表面处理后SB-444 N06625镍基合金材料进行腐蚀试验,对腐蚀试验后的材料进行取样和金相检测及对比分析。研究结果表明,供货状态材料表面的保护油脂会在热处理时燃烧并分解为碳及碳化物,造成试样渗碳现象,C元素含量的增多直接导致Cr元素与C元素在镍基合金材料近表面生成Cr23C6并析出,最终造成合金材料耐腐蚀性的下降。而对合金表面先进行脱脂处理,然后进行同样的热处理,试样的腐蚀性能只有轻微下降,可以满足使用要求。

The effect of corrosion resistance for SB-444 N06625 with different alloy surface states after stress-relief heat-treatment was studied by method A of ASTM G28—2002(Reapproved 2015)“Standard Test Method for Detecting Susceptibility to Intergranular Corrosion in Wrought,Nickel-rich,Chromium-bearing Alloys”.By comparing to the corrosion resistance in the supply states and other different surface states,the surface treatment states of materials before stress relief heat treatment can be recommended.The results was shown that the grease in the surface(without surface treatment)was burned to resolve to the carbide and carburized in the surface during the stress relief heat treatment,the Cr element in the alloy was combined with the increased C element to produce the precipitates of Cr23C6 in the alloy grain boundary,so that the corrosion resistance of alloy was decrease.Otherwise,the same heat treatment was performed on the same alloy with ungreased treatment for the alloy surface,the corrosion resistance just decreases a bit,and it can meet the requirements of usage.