GH3128合金激光焊接头组织与性能

Microstructure and properties of GH3128 alloy laser welding joint

关键词:  激光焊|镍基高温合金|微观组织|力学性能

Key words:  laser welding|nickel based superalloy|microstructure|mechanical property

摘要:

采用激光焊方法对3 mm厚GH3128合金进行对接焊，研究焊接工艺参数对焊缝成形的影响，同时与非熔化极惰性气体保护焊(tungsten inert gas welding，TIG焊)进行显微组织及力学性能的对比分析. 结果表明，在激光功率4 kW、焊接速度1.5 m/min和离焦量 + 3 mm的焊接工艺参数下可以获得成形良好的焊缝. 激光焊与TIG焊焊缝区组织均由奥氏体γ' + 脆性碳化物组成. 与TIG焊相比，激光焊焊缝区的组织晶粒细小，且分布于枝晶间和晶界处的碳化物尺寸较小，激光焊接头室温抗拉强度低12%，高温抗拉强度相近，室温轴向低周疲劳应力循环次数高4.5倍. 与TIG焊相比，激光焊接头室温抗拉强度低和低周疲劳性能高，主要是受焊接过程元素烧损和碳化物尺寸的影响.

Abstract:

The butt welding of GH3128 alloy with a thickness of 3 mm was carried out by laser welding, and the influence of welding process parameters on the weld formation was studied. At the same time, the microstructure of the weld and the mechanical properties of the joint were compared and analyzed with those of TIG welding. The results show that a well welding formation can be obtained under the welding process parameters of laser power 4 kW, welding speed 1.5 m/min and defocusing amount + 3 mm. The microstructure of the weld zone of laser welding and TIG welding is composed of austenite γ' + brittle carbides. Compared with TIG welding, the microstructure grain of laser welding weld zone is fine, and the carbide size distributed between dendrites and grain boundaries is smaller. The tensile strength of laser welding joint is 12% lower at room temperature and similar at high temperature. Low cycle fatigue at room temperature is 4.5 times higher. Laser welding joint has low tensile strength at room temperature and high low cycle fatigue performance, which is mainly affected by element burning loss and carbide size during welding.