Shot Peening To Prevent The Corrosion Cracking Of Austenitic Stainless Steels

Author:  Friske, W.H. and Page, J.P.
Source:  Conf Proc: ICSP-1, (p.485-492)
Doc ID:  1981065
Year of Publication:  1981
Abstract:  
A joint test program to develop shot peening as a technique for preventing corrosion cracking in austenitic stainless steels has been conducted. Laboratory-scale scoping tests demonstrated the feasibility of preventing stress corrosion cracking by shot peening. Conventional U-bend test specimens, when peened, survived 1000-h tests in the boiling 42% magnesium chloride stress corrosion test. Unpeened reference specimens commonly fractured within 1 or 2 hours in this test. Component tests demonstrated the practicality of the peening process for sizes and shapes that typify components in a reactor piping system. Pipe sections and cold-worked hexagonal tubes were tested. In all components, unpeened sections developed stress corrosion cracks within a few hours in the magnesium chloride test; in contrast, the shot-peened surfaces survived hundreds of hours. Intergranular corrosion can be prevented in austenitic stainless steels by severe shot peening prior to exposure to sensitizing temperatures. For this purpose, the surfaces must be severely cold worked by the shot peening to break up surface grains and grain boundaries. Two nondestructive testing techniques show promise for measuring the stresses or cold work imparted on the surface of the workpiece by peening. Descriptors: Shot peening; Stress corrosion; Intergranular corrosion; Stainless steels