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本文采用高斯热源模型,利用ANSYS软件对高镍合金与18-8钢异厚度异种材料接头TIG焊温度场进行三维瞬态有限元模拟,分析接头的热循环特点。结果表明,高镍合金与18-8钢焊接接头的温度场分布不对称,18-8钢侧温度场范围较大,焊缝偏离热源中心偏向不锈钢侧。热循环曲线梯度较大,高温停留时间短,有利于保证接头性能。采用金相显微镜、显微硬度计和电子探针(EPMA)对高镍合金与18-8钢接头进行显微组织观察、显微硬度测试和线扫描,并通过计算碳化物的吉布斯自由能进行热力学分析,研究焊缝周围元素分布特点;焊缝中的碳固溶在奥氏体和铁素体中,熔合区石墨片中的碳向基体扩散,容易形成Cr23C6等碳化物。
In this paper, the Gaussian heat source model was used to simulate the TIG welding temperature field of high-nickel alloy and 18-8 steel different-thickness dissimilar materials by ANSYS software. The thermal cycling characteristics of the joints were analyzed. The results show that the distribution of temperature field of welded joints between high nickel alloy and 18-8 steel is asymmetric, and the temperature field of 18-8 steel side is large, and the weld line deviates from the heat source center to the stainless steel side. Thermal gradient larger gradient, high temperature dwell time is short, help to ensure the joint performance. Microstructures, microhardness tests and line scans of high nickel alloys and 18-8 steel joints were performed using a metallographic microscope, a microhardness tester, and an electron probe (EPMA). The Gibbs Freeness Thermodynamic analysis can be carried out to study the characteristics of the elements distributed around the weld. The carbon in the weld is solid solution in the austenite and ferrite. The carbon in the graphite in the weld zone diffuses into the matrix and carbides such as Cr23C6 are easily formed.