GB616252A - Improvements in methods of thermally relieving residual stresses in welded metal members or structures - Google Patents

Abstract

In a method of thermally relieving residual stress in welded structures containing a zone of residual tensile stress and one or more complementary zones of residual compressive stress, the stress being parallel to the weld, a temperature gradient is established such that the zone of compressive stress is at a temperature sufficiently above that of the zone of tensile stress that the metal in the latter zone is stressed beyond the yield point but not sufficiently high to cause the metal in the zone of compressive stress to yield A temperature gradient of 50-175 DEG C. may be obtained by flame or electrically heating the zone of compressive stress, e.g. a band 4 or 5 inches from the weld, or cooling the zone of tensile stress, e.g. by covering the weld with solid carbon dioxide, or a combination of both; the weld in the first alternative may be kept cool by a jet of air or water. Residual transverse stresses may also be relieved by heating zones containing such stresses, to cause permanent deformation of the metal in such zones. Specification 552,806, [Group XXII], is referred to.