Patent ID: 7651576

Claim:
A method of preventing cold-worked stress corrosion cracking on a surface of iron steels or alloyed steels including stainless steels, the method comprising: irradiating an ultra-short femtosecond pulse from a kW class high average-powder laser light to the iron steels or alloyed steels including stainless steels to remove a surface layer and a hardened surface of the iron steels or alloyed steels, wherein an areal density of irradiated energy per pulse is less than 1 J/cm 2 ; and applying an ultrasonic gas jet containing a liquid mist of at least one of water, solution, liquid compound or liquefied gas, coaxially with the laser light, and concurrent to the irradiating, while the surface layer is being removed, measuring residual tensile stress of the surface layer using a quantum interference device, or a Hall effect magnetic filed measuring device, and monitoring the surface layer using an electron microscope, to confirm the removal of the surface layer and the hardened surface layer after the irradiating.