PHS1800热成形钢自动化TIG焊接成形特性及工艺优化

目的 研究不同焊接参数下PHS1800热成形钢自动化TIG焊接的成形特性及其工艺优化。方法 利用自动化TIG焊接技术对厚度为1.4 mm的PHS热成形钢板进行焊接，采用金相显微镜、扫描电子显微镜和万能实验机，对焊接接头的熔深、熔宽以及拉伸性能进行测试。结果 随着焊接速度的增大，焊缝熔深从板厚深度(1.4 mm)减小至0.99 mm，焊缝熔宽从8.69 mm减小至5.70 mm;随着焊接电流的增大，熔深从0.85 mm增大至板厚深度(1.4 mm)，熔宽从4.52 mm增大至9.83 mm;随着脉冲频率的增大，熔深从0.98 mm增大至1.35 mm，但熔宽变化相差不明显。基于L25(5³)正交实验，确定焊接接头最大拉伸载荷为23.34 kN，其断口为脆性断裂。结论 焊接电流对成形特性影响最大，焊接速度对拉伸性能影响最显著。为了得到成形效果良好的焊接接头，热输入量不宜过高，因此需适当增大焊接速度或降低焊接电流。制备出的焊接接头成形与力学性能均良好，且优化后的工艺参数如下:焊接速度为6 mm/s，焊接电流为116 A，脉冲频率为26 Hz，可为汽车企业实际生产提供一定的理论依据。

Forming Characteristics and Process Optimization of Automatic TIG Welding for PHS1800 Press Hardening Steel

The paper aims to study the forming characteristics and process optimization of PHS1800 press hardening steel automatic TIG welding under different welding parameters. Automatic TIG welding technology was used to weld PHS press hardening steel plate with the thickness of 1.4 mm. The welding depth and width were measured and tensile properties were tested by metallographic microscope, scanning electron microscope and universal testing machine. With the increase of welding speed, the welding depth decreased from plate thickness (1.4 mm) to 0.99 mm, and the welding width decreased from 8.69 mm to 5.70 mm. With the increase of welding current, the welding depth increased from 0.85 mm to plate thickness (1.4 mm), and the welding width increased from 4.52 mm to 9.83 mm. With the increase of pulse frequency, the welding depth increased from 0.98 mm to 1.35 mm, but the change of welding width was not obvious. Based on L25(53) orthogonal experiment, it is determined that the maximum tensile load of the welded joint is 23.34 kN, and the fracture is brittle fracture. Under the experimental conditions, welding current has the greatest influence on forming properties, and welding speed has the most significant effect on tensile properties. In order to obtain the welding joint with good forming effect, the heat input should not be too high, so the welding speed should be properly increased or the welding current should be reduced. The welded joint with good forming and mechanical properties can be prepared by the experiment. The optimized process parameters are as follows:welding speed of 6 mm/s, welding current of 116 A, pulse frequency of 26 Hz, which can provide some theoretical basis for the actual production of the automobile enterprises.