焊接电流对高强铝合金电阻点焊热裂纹的影响

摘要

In order to explore the effect rules of welding current on hot cracking during resistance spot welding, 2A12-T4 high strength aluminum alloy was resistance spot welded in DZ-3×63 three phase secondary rectifying spot welding machine with different welding current. Results showed that along with the increase of welding current, the solidification cracking appeared from scratch and proliferated constantly. When the welding current was 54% of equipment maximum current, the solidification cracking ran through the whole nugget. Liquidation cracking and beard cracking were also discovered in the heat affected zone, they both appeared when low melting point phase of grain boundary fusioned and tore by stress.%为了探究焊接电流对高强铝合金电阻点焊热裂纹的影响规律，只改变焊接电流大小，其他焊接参数保持不变，在DZ-3×63型三相次级整流点焊机上进行了2A12-T4高强铝合金的点焊试验。结果表明：随焊接电流的增大，结晶裂纹从无到有、从小到大，当焊接电流为设备最大电流Imax的54%时出现了贯穿整个熔核的结晶裂纹。试验还发现了存在于热影响区中的液化裂纹和胡须裂纹，它们都是晶界的低熔点相受热重新熔化在应力的作用下开裂形成的。