高速列车A7N01S-T铝合金焊接接头晶间腐蚀性能研究

Research on the intergranular corrosion of welding joint of A7N01S-T5 Al-Alloy for high-speed train

研究高速列车A7N01S-T5铝合金母材及焊接接头的晶间腐蚀行为,测定和观察腐蚀失重、硬度变化、断面和表面形貌。结果表明,在含氯的腐蚀介质中,焊接接头的腐蚀速率高于母材,热影响区是接头腐蚀最为严重的区域,腐蚀沿晶界扩展,形成网状裂纹。焊接热输入使热影响区的富锌强化相沿晶界连续析出,其电位最低因而成为腐蚀电池的阳极,不断发生电化学反应而溶解,导致晶界成为腐蚀的阳极活性通道,使腐蚀沿不断向金属内部发展。

This paper studied the intergranular corrosion property of A7N01-T5 Al-alloy and its welding joint.The weight loss,hardness change and morphology of section and surface after corrosion were tested.The result showed that the corrosion rate of welding joint was higher than that of the base,the heat affected zone（HAZ） was eorroded severely and the corrosion extended along grain boundary and connected as network.Zn2Mg strengthening phase of HAZ segregated continuously along grain boundary under the affected of heat-input of welding.This zinc-rich phase was anode in corrosion cell tbr its low potential and this made it dissolve preferentially thus forming active corrosion route along grain boundary, which made further COITOsion develop into inner alloy.