塑性加工を受けたオーステナイト系ステンレス鋼溶接継手部の低温鋭敏度の予測

Abstract

A nondestructive method has been investigated to predict the time when the degree of sensitization of a welded austenitic stainless steel joint having a plastic strain exceeds a critical degree of sensitization at a low temperature.The possibility of determining the plastic strain ratio of the welded joint from its hardness, the relationship between the time and the temperature of the accelerated tests needed for the degree of sensitization of the welded joints to exeed the critical degree of sensitization, and the sensitizations of the welded joints and the laboratory test specimens of the same intergranuler etch ratio and hardness as those of the welded joint were studied.The material used in this experimant was type 304 stainless steel plates having a 10 or 30% plastic strain ratio. To measure the degree of sensitization, the EPR test was used. The 10% oxalic acid etch test was used to determine the intergranuler etch ratio.From these experimental tests, the following conclusions were obtained. It is possible to determine the plastic strain ratio from the hardness. The relationship between the time and the temperature of the accelerated test needed for the degree of sensitization of the welded joint having a plastic strain to exceed a critical value is linear on the Arenius plots. It is possible to predict the time needed for the degree of sensitization of the welded joint to exceed a critical value by using the laboratory test specimen.