Abstract: On the basis of a finding that a magnetic hysteresis of a metal material, among magnetization characteristics changing with secular degradation of the metal material, shows a clear correspondence with the degree of degradation of the metal material, a change in such a magnetization characteristic is measured to estimate the degree of secular degradation of the metal material, In a typical embodiment, a superconducting quantum interference device is used to detect the magnetization characteristic of a measuring object. According to the present invention, the degree of embrittlement of a metal material used in an environment of high temperatures can be quickly detected in a non-destructive fashion so that the danger of brittle fracture of the metal material can be reliably prevented.

Abstract: A method for improving residual stress in a circumferential weld zone of a piping and the like which includes preventing deformation of the weld zone, and causing a local expansion or contraction of a portion of the piping axially spaced from the weld zone thereby effecting a plastic working so as to increase or decrease the diameter of piping. The method can effectively be applied to apparatus and pipe system which are used in a corrosive environment and under action of a static or dynamic outer load.

Abstract: A method of subjecting a welded structure to heat treatment in which a tensile yield is produced on an inner surface of the welded structure and a compressive yield is produced on an outer surface of the welded structure by the steps of placing a cooling medium in the interior of the welded structure and heating the outer surface of the welded structure to cause a difference in temperature to exist between the inner surface and other surface of the welded structure. The method further includes the step of locally heating a weld by means of a heating member to improve residual stress in a localized area of the weld and repeating the improvement of the residual stress regarding another localized area of the weld.

Abstract: AE signals due to a crack developed in a metal test object are detected by a number of AE sensors mounted on the metal test object. Based on time differences between the signals from the respective AE sensors, crack source points are determined. Then, based on the crack source points, a crack source plane is determined. The crack source plane is divided into a number of areas and a point of maximum number of crack source points in each of the areas is determined. Based on the points of maximum number of crack source points in the respective areas, a shape of the crack in the test object is determined.

Abstract: Disclosed is a method of heat-treating a pipe in which cooling water is passed through the pipe while the pipe is heated from the outer side thereof, so as to create a temperature differential between the outer and the inner sides of the pipe, so that the inner side of the pipe may be tension-yielded or the outer side of the pipe may be compression-yielded, thereby to generate a compressive residual stress and a tensile residual stress at the inner and the outer sides of the pipe, respectively.

Abstract: A method for supplying powder into a coating tank for electrophoretic powder coating comprises a first step for taking out a specified amount of plating bath of which the powder contained therein is reduced as a result of coating work, a second step in which the powder of much the same amount as the reduced amount of the powder is supplied to the plating bath taken out while the plating bath is being agitated to disperse the powder in the plating bath (the first dispersion) to form supplementary plating bath, a third step including the step for second dispersion of the powder in which the powder contained in the supplementary plating bath is further uniformly dispersed and a step for aging the supplementary plating bath with the dispersed powder, and a fourth step for supplying to the coating tank sufficiently aged supplementary plating bath which is obtained from the third step and has a high density of powder which is substantially uniformly dispersed in the supplementary plating bath, and an apparatus is o