Q&P1180高强钢激光焊接头的抗氢脆性能研究

Research on the hydrogen embrittlement resistance of laser welded joints of Q&P1180 high-strength steel

采用激光焊技术对汽车用Q&P1180高强钢进行焊接试验,分析焊接工艺参数对激光焊接头组织演变和性能的影响。选择综合力学性能较好的试样进行低应变速率拉伸试验,研究激光焊接头不同区域的微观组织对Q&P1180高强钢氢脆敏感性的影响。结果表明,当激光功率为2.5~3.5 kW、焊接速度为4.0 m/min(或激光功率为3.0 kW,焊接速度为3.6~4.2 m/min)时,Q&P1180高强钢激光焊获得了全焊透及表面成形良好的接头。不同激光功率和不同焊接速度下,焊缝区和热影响区的硬度均高于母材区的,且在焊缝的两边都存在一个软化区。在激光功率为3.0 kW、焊接速度为4.0 m/min时,激光焊接头的综合性能最佳。在预充氢的慢应变速率拉伸试验中,随着充氢电流密度的增大或充氢时间的延长,其抗拉强度和塑性逐渐下降。其中,当充氢电流密度为2 mA/cm^(2)、充氢时间为5 min时,氢脆敏感性因子为78.0%,具有较高的氢脆敏感性。

Laser welding technology was used to conduct welding tests on Q&P1180 high-strength steel for automobiles,and the influence of welding process parameters on the microstructure evolution and performance of laser welded joints was analyzed.The samples with good comprehensive mechanical properties were selected for low strain rate tensile test to study the effect of microstructure in different areas of laser welded joints on the hydrogen embrittlement sensitivity of Q&P1180 high-strength steel.The results show that when the laser power is 2.5-3.5 kW and the welding speed is 4.0 m/min(or when the laser power is 3.0 kW and the welding speed is 3.6-4.2 m/min),a joint with full penetration and good surface formation can be obtained by laser welding of Q&P1180 high-strength steel.Under different laser powers and welding speeds,the hardness of weld zone and heat-affected zone is higher than that of base metal zone,and there is a softening zone on both sides of the weld.When the laser power is 3.0 kW and the welding speed is 4.0 m/min,the comprehensive performance of the laser welded joint is the best.In the slow strain rate tensile tests of pre-charging hydrogen,the tensile strength and plasticity gradually decrease with the increase of hydrogen charging current density or the extension of hydrogen charging time.Among them,when the hydrogen charging current density is 2 mA/cm^(2)and the hydrogen charging time is 5 minutes,the hydrogen embrittlement sensitivity factor is 78.0%,indicating a high hydrogen embrittlement sensitivity.