奥氏体不锈钢-铜钎料钎焊界面反应行为分析

Investigation on interfacial reaction behavior of brazed joint of austenitic stainless steel/Cu filler metal

针对电弧钎焊奥氏体不锈钢时,易产生裂纹的问题,采用316LN不锈钢母材和多种铜基钎料,研究了电弧钎焊、炉中钎焊和真空钎焊316LN不锈钢和铜基钎料时的界面反应行为.结果表明,电弧钎焊条件下钎料对母材的润湿性随着电流的加大而提高,钎料沿母材晶界的扩散不明显,在电流较高时母材局部熔化,且易形成沿晶界裂纹.炉中钎焊过程中钎料沿母材晶界扩散明显,但不易形成裂纹;真空钎焊过程中钎料沿母材晶界扩散显著,形成较厚的界面层,但无裂纹出现.较大的焊接热应力以及钎料沿母材晶界扩散造成的晶界弱化是形成界面裂纹的必要条件.

Focused on the cracking problem encountered in arc brazing of austenitic stainless steel,in this study the interfacial reaction behaviors between 316 LN stainless steel and Cu-based brazing filler metal during arc brazing,furnace brazing and vacuum brazing processes were studied.The results revealed that during the arc brazing process,the wetting property of filler metals on the substrate was improved with increasing electric current,and the diffusion of filler metal along the grain boundaries of the substrate was not obvious.At higher electric current,a little bit of substrate melted and crack are more likely to form along the grain boundaries.During the furnace brazing process,the diffusion of filler metal along grain boundaries of substrate is obvious,but the boundaries were not likely to crack.During the vacuum brazing process,the diffusion of filler metal along grain boundary of the substrate was also obvious,forming an interfacial layer,but there was no cracking.A high thermal stress and grain-boundary weakness of the substrate induced by the diffusion of filler metal are necessary conditions for the interfacial cracking of the austenitic stainless steel substrate.