METHOD FOR IMPROVING RESIDUAL STRESS IN TUBULAR BODY

摘要

PROBLEM TO BE SOLVED: To provide a method and an apparatus for improving the residual stress in a tubular body, wherein the residual stress can surely be improved without depending on the setting-state and the constituting-state of the tubular body by regulating a control ranges of working conditions.

SOLUTION: When the residual stress in the piping 2 is improved by shifting the irradiation range S to the peripheral direction while locally irradiating the outer peripheral surface of a welded portion C of a cylindrical piping 2 with a laser beam 5a, a plurality of thermal couples 9 is set to the piping 2 to be executed, and the temperature history on the outer surface of the piping 2 due to irradiation with the laser beam 5a is measured to control the temperature history.

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