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采用中频逆变点焊机对1.6mm厚的DP590钢板进行了电阻点焊试验,并对焊点的组织和硬度进行了分析,研究了焊接电流和焊接时间对熔核直径、焊点强度的影响。结果表明,点焊接头熔合区组织为板条马氏体,粗晶区为粗大的板条马氏体,细晶区为细小的马氏体和少量的铁素体;接头熔核区平均硬度约340HV10,热影响区最高硬度为400 HV10,均高于母材。在一定范围内,熔核尺寸、焊点的正拉强度和拉剪强度均随着焊接电流和焊接时间的增加而增加,当焊接电流过大时,又呈现降低的趋势。
Resistance spot welding of 1.6mm thick DP590 steel was carried out by using IF inverter spot welding machine. The microstructure and hardness of the welded joints were analyzed. The effects of welding current and welding time on nugget diameter and welding spot strength were studied . The results show that the microstructure of spot welded joints is lath martensite, the coarse grain zone is coarse lath martensite, the fine grain zone is fine martensite and a small amount of ferrite. The average hardness About 340HV10, heat-affected zone maximum hardness of 400 HV10, are higher than the base metal. Within a certain range, the size of nugget, the positive tensile strength and the tensile strength of the solder joint all increase with the increase of welding current and welding time. When the welding current is too large, the tensile strength decreases again.