基于镀锡银钎料钎焊304不锈钢接头的腐蚀行为

为揭示304不锈钢钎焊接头的腐蚀行为，以BAg50CuZn钎料为基材，采用电镀扩散工艺制备AgCuZnSn钎料，对304不锈钢进行感应钎焊，在60 ℃,3.5% NaCl溶液中评价不锈钢接头的局部腐蚀性，借助扫描电镜对其腐蚀形貌进行分析. 结果表明，经NaCl溶液腐蚀后，钎缝与不锈钢界面出现较长的腐蚀沟；304不锈钢表面腐蚀较严重，存在大范围坑洞、裂纹等缺欠，而钎缝区几乎无腐蚀缺欠，优先被腐蚀的是富铜相. 随着腐蚀时间延长，钎缝和304不锈钢的腐蚀速率均呈现先升高后降低的趋势，钎缝腐蚀速率略低于母材；腐蚀2.5 h后，钎缝区和304不锈钢的平均腐蚀速率分别为0.098和0.104 g/(m2·h).

Corrosion behaviors of 304 stainless steel joints brazed with Sn-electroplated Ag brazing alloys

To reveal the corrosion behavior of 304 stainless steel brazed joints in NaCl solution, the high Sn content of AgCuZnSn brazing alloys was prepared successfully by electroplating and thermal diffusion process. 304 stainless steels were induction brazed by using the prepared brazing alloys. 3.5% NaCl solution at the temperature of 60 ℃ was used to simulate seawater environment and determine the localized corrosion characteristic of 304 stainless steel brazed joints. The corrosion morphology was observed with scanning electron microscopy (SEM). The results showed that corrosion groove was found on the interface region between 304 stainless steel and brazing seam when the brazed joints were dipped in the solution of 3.5 % NaCl for 2.5 h. The serious corrosion phenomenon happened and a wide range of defects such as holes and cracks occurred on the surface of the 304 stainless steel, while almost no corrosion defects occurred in the brazing seam zone and Cu-rich phase was corroded preferably. The corrosion rate of brazing seam and base metal initially increased and then decreased with the increase of corrosion time. The corrosion rate of brazing seam was slightly lower than that of base metal. The average corrosion rates of brazing seam area and 304 stainless steel were 0.098 and 0.104 g/(m2·h) respectively.