SEDL / STP / STP770-EB / STP32428S

Assessment of High-Temperature Low-Cycle Fatigue Life of Austenitic Stainless Steels by Using Intergranular Damage as a Correlating Parameter

Levaillant, C
Centre des Matériaux, École Nationale Supérieure des Mines de Paris,

Pineau, A
Centre des Matériaux, École Nationale Supérieure des Mines de Paris,

Pages: 25    Published: Jan 1982

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Abstract

Strain-controlled continuous fatigue and creep-fatigue experiments are reported for two types of 316 steel tested at 600°C (1112°F). It is shown that, although the continuous fatigue properties of the two materials are very similar, the one containing a controlled amount of nitrogen exhibits a better creep-fatigue resistance than the other alloy. Detailed measurements of intergranular damage made either on the fracture surfaces or in the bulk of creep-fatigue specimens indicate that the susceptibility of the materials to the effect of tensile hold times can be related to their propensity to intergranular cracking. A stress relaxation-propagation reduction factor per cycle correlation is proposed in order to account for the detrimental effect of tensile hold times on the fatigue life. This correlation relies upon experimental results on austenitic stainless steels published in the literature. It is shown that the proposed approach, derived largely from the quantitative measurement of intergranular damage, holds some promise for predictive purposes.