高速列车A7N01S-T5铝合金焊接接头盐雾腐蚀行为分析

Analysis on corrosion behavior of welded joint of A7N01ST5 aluminum alloy for high-speed train

关键词:  高速列车  盐雾腐蚀  点蚀  剥落腐蚀

Key words:  high speed train  salt fog corrosion  pitting corrosion  denudation corrosion

摘要:

选取了中国某类型高速列车常用的A7N01S-T5铝合金焊接接头,研究A7N01S-T5铝合金焊接接头在盐雾腐蚀条件下的腐蚀失效行为.结果表明,腐蚀后在焊接接头表面上生成了大量腐蚀产物,并且产生了较多的腐蚀坑,腐蚀坑最深处位于热影响区,蚀坑深度为35.4μm,蚀坑面积率为43.6%.铝合金焊接接头先发生点蚀,随着蚀坑深度逐渐向内部扩展,焊接接头以剥落腐蚀为主,造成焊接接头材料脱落失效.铝合金焊接过程中造成的局部热处理使焊接热影响区晶粒粗大,成为焊接接头中对腐蚀最为敏感的区域.

Abstract:

Salt fog corrosion tests were employed to observe the corrosion behavior of welded joint of A7N01S-T5 aluminum alloy for high-speed train. The results showed that many corrosion products and pits distributed on the surface of the welded joint. The deepest corrosion pit was in the area of heat affected zone (HAZ), the depth of the corrosion pit was 35.4μm, the corrosion area ratio was 43.6%. The corrosion mechanism of the welded joint was pitting corrosion first, and then came to denudation corrosion with the depth of the corrosion pit spreading into the inner surface of the joint. The grains of the HAZ zone were coarsened with the influence of the partially overhent in the welding, and the HAZ was very sensitive to corrosion in welded joint in the salt fog corrosion test.