Practicality of Establishing Threshold Values To Eliminate Stress Corrosion Failures in Metals and Alloys

Abstract

Abstract A review is offered on the significance of many factors which could affect the stress corrosion behavior of materials. These include such items as (1) method of test, (2) variations normally present in the materials conforming to the same specification, (3) slight variations in test environment or metallurgical structure of the metal, (4) accelerated corrosion attack (galvanic or crevice), (5) residual stress, and (6) nature of corrosion attack. Based on this review, it was evident that all the factors do not act independently; instead, there is a complex mutual interaction. As a result of these factors, it has been concluded that the stress corrosion problem cannot be entirely eliminated at this time through control of specific parameters to established threshold values. The recommended approach is selection of an alternate resistant material. Other approaches to minimize the problem are proper design, reduction of the corrosivity of the environment, reduction of effective stress, or use of a protective layer. Evaluation under actual service conditions is an essential requirement. The possible danger of localized failure or increasing porosity of a protective layer with continued exposure of the base metal also is emphasized. Special attention is given in this study to the behavior of AISI 410 steel. 3.5.8