PHS1800热成形钢电阻点焊接头截面特性及工艺优化

目的 研究不同参数下PHS1800热成形钢电阻点焊接头截面特性及其工艺。方法 利用金相显微镜、扫描电子显微镜和万能试验机，对点焊接头的焊点熔透率、压痕率、熔核直径、压痕直径及拉伸性能进行测试。结果 随着焊接时间的增加，各截面特性总体呈线性增长的趋势，当焊接时间超过0.6 s时，接头熔核直径减小；随着焊接电流的增大，各截面特性整体呈上升的趋势，当焊接电流为11.5 kA时，熔透率达到峰值，继续增大焊接电流，压痕率迅速上升；随着焊接压力的增大，熔透率增至59.17%后不断减小，压痕率不断增大，熔核直径与压痕直径无明显变化。基于三因素八水平正交实验，确定点焊接头最大拉伸载荷为16.54 kN，其断口为脆性断裂。结论 焊接时间和焊接电流对点焊接头截面特性的影响较为显著，拉伸性能受焊接电流的影响最大。实验得到了成形良好的焊接接头，最优参数如下：焊接时间为0.6s，焊接电流为11.5 kA，焊接压力为2.0 kN。本实验可为热成形钢在汽车加工中的应用提供理论基础和技术支持。

Section Characteristics and Process Optimization of Resistance Spot Welding Joint for PHS1800 Press Hardening Steel

The work aims to study the section characteristics and process of resistance spot welding joint for PHS1800 press hardening steel under different parameters. The penetration rate, indentation rate, nugget diameter, indentation diameter and tensile properties of spot welding joint were tested by metallographic microscope, scanning electron microscope and universal testing machine. With the increase of welding time, the overall trend of each section characteristic increased linearly. When the welding time exceeded 0.6 s, the nugget diameter of the joint decreased. With the increase of welding current, the overall characteristics of each section showed an increasing trend. When the welding current was 11.5 kA, the penetration rate reached the peak value, and the indentation rate increased rapidly when the welding current continued to increase. With the increase of welding pressure, the penetration rate increased to 59.17% and then decreased, the indentation rate increased, and the nugget diameter and indentation diameter did not change significantly. Based on the orthogonal experiment of 3 factors and 8 levels, it was determined that the maximum tensile load of the spot welding joint was 16.54 kN, and the fracture was brittle. The welding time and welding current have a significant effect on the section characteristics of spot welded joints, and the tensile properties are most affected by the welding current. Under the experimental conditions, a well-formed welding joint can be obtained. The optimal parameters are welding time 0.6 s, welding current 11.5 kA and welding pressure 2.0 kN. This experiment can provide theoretical basis and technical support for the application of press hardening steel in automobile processing.