| 摘要 |
PROBLEM TO BE SOLVED: To improve a stress corrosion crack resistance by heating a metallic material surface as spotting state with a laser beam, forming a small melting metal pool part and rapidly solidifying the molten metal pool part while shifting a heating point from the molten metal pool part. SOLUTION: At the time of shifting the heating point P by the irradiation of a laser beam L from the molten metal pool part R by shifting the treating material 1 supported with an X-Y table 5, the heat of the molten metal pool part R is transferred to the material to be treated 1 around the molten metal pool part and the metal of the molten metal pool part R is quickly solidified and further, the molten metal pool part R is newly formed on the metal surface 1a with the laser beam L. It is a problem whether a sensitive zone in the metallurgical structure of the material 1 to be treated is developed or not just below the molten metal pool part R caused by affection of the heat of the pool part, but in the case of being rapid cooling speed of the molten metal pool part R, the sensitive zone is not developed but solidified. In such a way, the stress corrosion crack resistance can be improved by reducing the vol. and the heat capacity of the molten metal pool part R and quickening the speed of the heating point P to rapidly cool the molten metal pool part R. |
