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Vol.35, No.8, 1041 ~ 1047, 1997
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| Title |
| Study of Welding Behavior in Iconel 600 by Nd : YAG Laser Beam |
| 김재형 , 김도훈 , 정진만 , 김철중 Jae Hyung Kim , To Hoon Kim , Chin Man Chung , Cheol Jung Kim |
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| Abstract |
| Lap joint welding of 1.2 ㎜ thick Inconel 600 plate was performed by Nd:YAG laser. Welding parameters such as pulse width, repetition rate, peak power and scanning speed, were varied in this experiment. The optimum welding condition observed were 6-12ms pulse width, 15-50㎐ repetition rate, 1.5-3.0㎾ peak power and 288-360㎜/min scanning speed. Cracks were not observed in the weldment. An aspect ratio of 0.7-1.4 was obtained by means of controlling the above parameters. Microscopic analysis revealed that the weldment consisted of a planar front solidification zone which formed at the initial stage of solidification, and a cellular-dendrite solidification zone produced by rapid cooling. Epitaxial growth from base metal was also observed. Post-welding heat treatment was performed in order to relieve residual stresses induced by welding. Results obtained from the Huey test and ABI test, the optimum heat treatment condition was observed at 5 min. annealing at 640-700℃. It was found that the susceptibility to intergranular corrosion attack of the weldment was approximately three times higher than that of the base metal and the base metal corroded more severely than the weldment. This occurrence is believed to be caused by the sensitization of the base metal by heat input during welding. It was also observed that the intergranular corrosion rate was also accelerated as heat treatment temperature was increased. ABI tests showed that residual tensile stress was present in the weldment and was subsequently relieved by post-welding heat treatment. |
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