| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method for preventing cold working stress corrosion cracking without considering elimination of a corrosive factor such as a moisture content and a chlorine component and limit of heat resistance, chemical resistance or the like of an object to be worked, and without impairing strength required for a final product. <P>SOLUTION: Steel having a surface hardened layer where tensile stress remains by cold working is located in a protective wall having an opened end, an inert gas is jetted at high speed, and the surface hardened layer is evaporated in a lamp soot state by irradiating fs region extra-short pulse kW class high average output laser having irradiation energy areal density of 0.5 J/cm<SP>2</SP>or less per one pulse and a pulse width of 5 ps or less to the surface of the steel. Temperature increase is suppressed by preventing oxidation, convection, and accumulation to a surrounding of a laser irradiation field of a peeled substance from the surface hardened layer by the inert gas, and compressive residual stress is not generated and tensile residual stress by evaporation heat is not generated at a new surface emerged by the evaporation of the surface hardened layer. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
