Published: Jan 1988
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This paper presents the results of an experiment to determine the effect of elevated temperature on residual stresses present in, and the fatigue life of, shot peened 403 stainless steel. The first step involved testing simulated Almen A strips made from strip quench and tempered to 229–235 HB. The strips were shot peened to 8–10 A and subjected to temperatures ranging from 150 to 595°C (300 to 1100°F) for up to 1000 h. The amount of relaxation of the height of each sample was then measured at several intervals during the test. The data revealed that the change at 150°C (300°F) after 50 h was equal to that at 260°C (500°F). This drop was unexpected, as a review of available literature indicated residual stresses in carbon steel would not start to drop until 260°C (500°F), with stainless steels resistant to a much higher temperature. Measurement via x-ray diffraction showed the residual stress dropped from -529 MPa (-76.7 ksi) at room temperature to -269 MPa (-39 ksi) after exposure to 150°C (300°F) and to -112 MPa (-16.3 ksi) after exposure to 595°C (1100°F).
The second part of the paper presents the results of testing shot peened 403 stainless steel rotating beam fatigue test bars at room temperature, 260, and 400°C (500°F and 750°F). The data shows the endurance limit increases by 16 percentage points at room temperature and 6 percentage points at 260 and 400°C (500 and 750°F).
fatigue (materials), stainless steels, elevated temperature, residual stress, rotating-bending tests
Metallurgical engineer, Dresser-Rand, Wellsville, NY