Invar36合金中厚板K-TIG焊接头组织及性能分析

Mechanical Properties and Microstructure Analysis of Middle-thick Invar36 Alloy Plate Weld Joints Using K-TIG Welding

Invar36合金具有与航空复合材料相近的低膨胀系数,是制备航空复合材料模具的首选材料,涉及材料厚度多介于10~20mm,采用传统MIG多层多道焊工艺存在焊接效率低、使用成本高及成品率低等问题。鉴于此,选用厚度为10mm和19mm厚Invar36合金,采用K-TIG焊和摆动MIG焊工艺进行了试验研究。焊缝组织及接头性能分析表明,10mm和19mm厚Invar36合金焊缝各区域均未发生相变,热影响区为粗大的奥氏体等轴晶,焊缝为奥氏体柱状晶。10mm厚Invar36合金K-TIG接头热影响区晶粒尺寸为178μm;19mm厚Invar36合金K-TIG侧和摆动MIG侧的热影响区晶粒尺寸分别为150,131μm。10mm和19mm厚Invar36合金接头抗拉强度分别为427,452MPa,延伸率分别为31%和36%。

Invar36 alloy has a low expansion coefficient similar to that of aerospace composite materials.It is the first choice for the preparation of aerospace composite material molds.The thickness of the materials involved is mostly between 10~20 mm.The traditional MIG multi-layer multi-pass welding process has problems of low welding efficiency,high cost and low yield.In this study,10 mm and 19 mm thick Invar36 alloys were selected,and K-TIG and MIG welding were used for experimental research.The microstructure and performance analysis of the welds of the two plate thicknesses showed that there was no phase transformation in the welds of the 10 mm and 19 mm thick Invar36 alloys,the heat-affected zone was coarse austenite equiaxed crystals,and the welds were austenite columnar crystals.The heat-affected grain size of the 10 mm thick Invar36 alloy K-TIG joint was 178μm,and the heat-affected zone grain size of the 19 mm thick Invar36 alloy K-TIG side and swing MIG side were 150μm and 131μm,respectively.The tensile strength of 10 mm and 19 mm thick Invar36 alloy joints were 427 MPa and 452 MPa,and the elongation was 31%and 36%,respectively.