拘束緩和式U型高温割れ試験による各種合金の高温割れ感受性の比較 : Ni基耐熱超合金のレーザ溶接性に関する研究(第2報)

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This study was carried out quantitatively to evaluate the hot cracking susceptibilities of various Ni-base superalloys and the effect of grain size on hot cracking susceptibility during laser welding. Ni-base superalloys used were Inconel 718,Inconel X-750,Inconel 617,Inconel 625,Nimonic 90 Waspaloy, Hastelloy X. The grain size of Inconel 718 varied from about 10 to 110 μm. In this study, the hot craking susceptibility was evaluated by a modified U-type hot cracking tester during CO_2 laser welding. Samples were solution heat-treated before welding and welded with laser powers of 3 and 5 kW and with a traveling speed of 0.5 to 3 m/min. The hot cracking occurring in the weldment during the bead on plate test was reproduced on the U-type hot cracking test. Consequently, the liquation cracking susceptibilities of various Ni-base superalloys decreased in the order of Waspaloy, Inconel 617,Inconel 718,Hastelloy X, Inonel 625,Inconel X-750 and Nimonic 90. Liquation cracking susceptibility of Inconel 718 increased with an increase in grain size.
1999-05-05