| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for improving a fatigue strength of metal by transforming a tensile strength as the residual stress existing in the inner part of the metal and a welded part in the metal into a compressed stress. SOLUTION: This method for improving the fatigue strength in the metal is characterized in that after heating at least a part of the metal to not lower than the plastic strain generating temperature, the residual stress in the metal is reduced by rotating the metal in a plane containing this metal till cooling to a room temperature. As the rotating method, in the case of using n times/min for the number of rotation and r mm for distance from the center of the rotation to fatigue crack generated portion, it is desirable to rotate the metal so that (n×r) becomes 2,000 to 30,000. COPYRIGHT: (C)2005,JPO&NCIPI
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