NONDESTRUCTIVE LIFE-EXPECTANCY EVALUATING METHOD OF HEAT RESISTING STEEL

摘要

PURPOSE:To obtain highly reliable value in a short time, by classifying the concentration of each analyzing point in an arbitrary concentration range, using the occupying rate of the number of the analyzing points in the total analyzing points as an area ratio, and obtaining concentration distribution for each concentration. CONSTITUTION:After the surface of a material to be checked is etched, a replica film is transferred on the surface. Carbon is evaporated on the surface. The concentrations of alloy elements of the deposited material on the surface are analyzed at many points with X-ray microanalyzer and the like. The concentration at each analyzing point is classified into an arbitrary concentration range. The occupying rate of the number of the analyzing points in the total number of the analyzing points is used as an area ratio. The concentration distribution of the deposited material is obtained for each concentration and a graph is formed as in the Figure. Thereafter, the concentration distributions of alloy elements of the deposited material of heat resisting steel, which has been used under the various conditions, is determined beforehand. Relationship between the determination and the life consumption rate of, e.g., creep-rupture and the like, in the destruction test of the heat resisting steel or stress analysis is shown in a life-expectancy evaluating reference-line diagram. The determined value of the concentration distribution of the deposited alloy elements of the heat resisting steel is compared with the reference line diagram. Thus the life expectancy of the heat resisting steel is obtained.