The influence of processing on the fatigue and fatigue-creep behaviour of stainless steels

Processing of engineering materials is generally performed to enhance their simple properties such as proof stress and ductility. Since many components experience complex conditions in service, it is important to determine how these are also influenced by processing. From a survey of published data, the paper explores the effects of prior ageing and deformation on the tensile, fatigue and fatigue-creep behaviour of stainless steels. Extended high temperature ageing is found to produce an increase in proof stress and a fall in ductility in comparison to the solution treated condition. Endurance during both continuous cycling fatigue and with cycles containing dwell periods is increased. While prior cold working is generally beneficial to the fatigue resistance of Type 316 stainless steel, it impairs performance in fatigue-creep. However, most cyclic lives fall within a +/- 2x band. These findings are considered in terms of possible controlling mechanisms.