Mechanical properties of lanthanum-containing Inconel cast alloy 718 welds. Study of weldability of Inconel cast alloy 718 (Report 9)

摘要

Previous articles in this series have shown that, through addition of 0.2-0.3 mass% lanthanum and cerium to Inconel cast alloy 718, the HAZ cracking susceptibility of laser welds can be appreciably improved. Lanthanum and cerium are also shown to be effective for cracking susceptibility improvement. To evaluate the effectiveness of lanthanum and cerium addition to Inconel cast alloy 718, it is important to understand the mechanical properties of its welded joints. This article is intended to clarify the mechanical properties of welded joints as part of an effort to evaluate the weldability of Inconel cast alloy 718 containing the rare earth metal lanthanum, describing tensile tests of laser welded joints at room and elevated temperatures. For reference, the mechanical properties of La-free TIG, laser and electron beam welded joints are also investigated. On the basis of the results obtained, the effect of lanthanum on improvement of the tensile properties of the welded joints is further discussed.