DH980高强钢电阻点焊工艺研究

Study on Resistance Spot Welding Process of DH980 High Strength Steel

以汽车车身DH980-GI钢板电阻点焊为研究对象,通过参数实验优化设计,接头强度、接头硬度和接头抗点焊液态金属脆(LME)分析等手段,研究了焊接电流等参数对钢板电阻点焊接接头性能的影响,并对板材的点焊液态金属脆敏感性进行测试研究。试验结果显示,在电极压力4.5 kN、焊接时间380 ms的条件下,焊接电流在6.8~8.1 kA内,不同电流的接头熔核区域显微硬度值相近,均在470~510 HV内,熔核直径均满足标准要求。LME测试结果显示,在6.8~10.5 kA电流范围内未出现LME裂纹,而11~14.5 kA电流范围内出现了A类LME裂纹。力学性能测试结果显示,在焊接电流6.8 kA时,接头抗剪强度为901~911 MPa,在焊接电流8.1 kA时,为738~783 MPa,抗剪力均达到21 kN以上,均满足标准要求。

The resistance spot welding of DH980-GI steel sheet of body-in-white was taken as the research object.By means of optimization design of welding parameters and analysis of joint strength,hardness and liquid metal embrittlement(LME),the influence of welding current and other parameters on the performance of resistance spot welding joint of steel sheet was studied.In the meantime,the brittleness sensitivity of spot welding liquid metal of the was also analyzed.The experimental results show that under the conditions of 4.5 kN electrode pressure and 380 ms welding time,the microhardness values of the fusion zone of the joints with different currents are similar,all within the range of 470~510 HV,and the fusion zone diameters meet the standard requirements.The LME test results show that no LME cracks were observed in the current range of 6.8~10.5 kA,while A-type LME cracks appeared in the current range of 11~14.5 kA.The mechanical properties test results show that when the welding current is 6.8 kA,the shear strength of the joint is 901~911 MPa,and when the welding current is 8.1 kA,it is 738~783 MPa.The shear force is above 21 kN,which meets the standard requirements.