Residual Stresses and Retained Austenite in Shot Peened Steels

Author:  D. Kirk
Source:  The Shot Peener magazine, Vol 14 / Issue 1, Spring 2000
Doc ID:  2000063
Year of Publication:  2000
Reprinted with permission from Proceedings of ICSP1. Editor: A. Niku-Lari ABSTRACT X-ray diffractometry has been used to examine the variation of residual stress across shot peened surfaces, the transformation of austenite to martensite on peening and the decay of surface residual stress during fatigue testing of peened specimens. It is shown that masking gives rise to tensile surface residual stresses adjacent to the peened area. Peening of austenitic stainless steel produces surface martensite in amounts that depend upon the composition of the steel. Transformation of retained austenite on peening of carburised steel is found to give a substantial improvement in the surface and sub-surface residual stresses. Shot peened austenitic stainless steel is found to lose its compressive surface residual stress on fatigue testing at high levels of applied alternating stress. The fatigue and corrosion fatigue properties of the shot peened stainless steel are then found to be inferior to those of as-polished steel but are superior at lower stress levels.

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