热处理对特种设备用高强钢激光–电弧复合焊接头氢脆断裂行为的影响研究

目的 提高800 MPa级特种设备用低碳贝氏体高强钢激光–电弧复合焊接头的抗氢脆性能。方法 采用预充氢后慢应变速率拉伸试样的方法，定量评估焊态、焊后直接高温回火和焊后调质3种状态下800MPa级低碳贝氏体高强钢激光–电弧复合焊接头的氢脆敏感性，结合扫描电镜下的初始微观组织和断裂特征，讨论抗氢脆性能的改善机理。结果 焊后调质处理有效消除了焊接热循环形成的马氏体组织，使接头各区域的微观组织趋于一致，接头的抗氢脆性能较焊态和直接焊后高温回火态的显著提高，断裂特征也从沿晶和穿晶的混合断裂转变为穿晶解理断裂。结论 焊后调质处理可以有效提高800MPa级低碳贝氏体高强钢激光–电弧复合焊接头的抗氢脆性能。

Effect of Heat Treatment on Hydrogen Embrittlement Behavior of Laser-Arc Hybrid Welded Joint of High-Strength Steel for Special Equipment

The work aims to improve the hydrogen embrittlement (HE) resistance of the laser-arc hybrid welded joint of 800 MPa low carbon bainite high-strength steel for special equipment. Slow strain rate tensile test was adopted after hydrogen charging to quantitatively evaluate the HE susceptibility of the three samples under the as-welded state, post-welding direct high-temperature tempering and post-welding modulation. In combination with the initial microstructure and fracture characteristics analysis by scanning electron microscopy (SEM), the improvement mechanism of HE resistance was discussed. The post-welding modulation effectively eliminated the martensite structure formed by the welding thermal cycle, and made the microstructure regions of the joint consistent. The HE resistance of the joint was significantly improved compared with that of the as-welded joint and direct post-welding high-temperature tempered joint, and the fracture characteristics of the joint changed from mixed intergranular and transgranular fracture to transgranular cleavage fracture. Post-welding modulation can effectively improve the HE resistance of laser-arc hybrid welded joint of the 800 MPa low carbon bainite high-strength steel.