HAZ割れ感受性に及ぼす希土類元素の影響
—Inconel718鋳造合金の溶接性に関する研究 (第7報)—
2002 年 20 巻 1 号 p. 78-86
詳細
2002 年 20 巻 1 号 p. 78-86
A study was carried out to determine the effect of rare earth metal (La, Ce) addition on the HAZ cracking susceptibility of cast alloy 718 welds. The cast alloy 718 containing rare earth metal was melted in an alumina crucible heated in ambient argon by an induction generator and then poured into a copper mold. The contents of La and Ce addition were varied from 0 to 0.7 mass%. HAZ cracking susceptibility of the La and Ce-added cast alloy 718 in TIG and laser welds were evaluated by using self-restraint U-type hot cracking test and bead-on-plate test, respectively. The values of grain size and aspect ratio of grain in the La, Ce containing specimens were much less than those of rare earth metal-free specimens. Compared with the Ce-added specimen, the value of cumulative crack length was significantly lower for the La-added specimens. The La and Ce addition up to 0.3 mass% was found to have a beneficial effect to reduce the HAZ cracking susceptibility. Furthermore, no HAZ cracking was observed for the specimen containing 0.2 to 0.3 mass% La. However, when the amount of La and Ce addition exceeded 0.3 mass%, the HAZ cracking susceptibility contrarily increased.
