基于田口法的DP980/SPCC电阻点焊工艺优化及接头组织和性能分析

Microstructure and mechanical properties of DP980/SPCC dissimilar steel plate resistance spot welded joints based on optimal parameters of Taguchi method

文中以冷轧DP980高强钢板与SPCC低碳钢板作为研究对象,基于田口法优化电阻焊接参数,并对最优参数的焊接接头进行组织性能分析。结果表明,在焊接电流10.5 kA、焊接时间30 cycles、电极压力3 kN、维持时间10 cycles的条件下,接头力学性能最优;且接头实现熔核剥离断裂,为韧性断裂,熔核剥离断裂起始位置位于熔核边缘处SPCC母材,最大拉伸力为11.78 kN;点焊接头主要为熔核区、热影响区、母材区3个区域;熔核区的显微组织主要为马氏体,DP980高强钢一侧热影响区的显微组织组织主要为马氏体和铁素体,SPCC低碳钢一侧热影响区的显微组织主要为马氏体、铁素体和珠光体。DP980高强钢热影响区硬度最高,其次为熔核区、SPCC热影响区,SPCC母材硬度最低。

In this paper,cold-rolled DP980 high-strength steel plate and SPCC low-carbon steel plate were taken as research objects,the resistance welding parameters were optimized based on Taguchi method,and the microstructure and properties of welded joints with the optimal parameters were analyzed.The results showed that under the conditions of welding current 10.5 kA,welding time 30 cycles,electrode pressure 3 kN and holding time 10 cycles,the joint had the best mechanical properties.And the joint realized nugget peel fracture,which was ductile fracture.The starting position of nugget peel fracture was located at SPCC parent metal at the edge of nugget,and the maximum tensile force was 11.78 kN.Spot welding joints mainly included nugget zone,heat affected zone and base metal zone.The microstructure of nugget zone was mainly martensite,the microstructure of heat affected zone of DP980 high strength steel was mainly martensite and ferrite,and that of SPCC low carbon steel was mainly martensite,ferrite and pearlite.Hardness of heat affected zone of DP980 high strength steel was the highest,followed by nugget zone and SPCC heat affected zone,and hardness of SPCC base metal was the lowest.