热处理工艺对TRIP980钢板点焊性能的影响

采用不同焊接工艺对TRIP980钢板进行点焊试验，研究了焊接电流、焊前预热及焊后热处理工艺对点焊性能的影响. 结果表明，随着焊接电流的增大，焊点的熔核直径和拉剪力均增大，但当电流过大而发生飞溅时，焊点的熔核直径和拉剪力开始减小. 焊前预热工艺可提高点焊飞溅电流，进而可以获得更大的熔核直径及拉剪力. 在对焊点进行焊后热处理的情况下，当焊接电流与焊后热处理电流之间的冷却时间超过900 ms时，可显著改善熔核组织，降低熔核硬度，提高焊点拉剪力.

Effect of heat treatments on resistance spot weldability of TRIP 980 steel

Cold rolled TRIP 980 steel sheets were resistance spot welded by different welding procedures. The effects of welding current, preheating and postweld heat treatments on the resistance spot weldability were studied. The results show that the increasing welding current increases the nugget diameter and tensile shear strength of spot weld. However, when the welding current is large enough to cause spatter, the nugget diameter and tensile shear strength of spot weld decrease. The preheating process raises the spatter occurring current, which results in larger nugget diameter and tensile shear strength. Under the condition of adding postweld heat treatment to spot weld, when the cooling time between welding current and postweld heat treatment current was larger than 900 ms, the microstructure of weld nugget was improved significantly, which decreased the hardness of weld nugget and increased the tensile shear strength of spot weld.