The effects of pre-deformation on the subsequent fatigue behaviors of SUS 430 Stainless Steel in load-control

The purpose of this study is to investigate the fatigue behavior of the SUS 430 Stainless Steel after the tensile pre-deformation is subjected to a symmetric loading. The investigations have been performed in three levels of pre-deformation. Cyclic deformation following pre-deformation was carried out in tension-compression fatigue test experiment at room temperature. The pre-deformation was induced on the specimen by a tensile test under strain control at 5%, 8%, and 12% strain level at a strain rate of 10(-4) s(-1), respectively. In this paper, the effects of the cyclic deformation behaviors with different pre-strain levels were compared with the fatigue responses without pre-strain. Based on the comparison, it is found that the pre-strain caused evident changes in fatigue behaviors such as cyclic softening response, cyclic creep response, and cycles to failure. Generally, as compared to the as-received material, the softening response increased with increasing pre-strain level. A pronounced cyclic compressive creep occurred in the specimen with and without pre-strain level effect in all applied loading cases. This could be attributed to an-isotropy between tension and compression, resulting in the occurrence of compressive cyclic creep on the tested material during cyclic loading. Moreover, the stable total compressive creep strain scaled with increasing tensile pre-strain level for same cyclic loading. For the effect of pre-strain on fatigue resistance, a decrease in the number of cycles to failure was observed and the extent of the decrease also increased with increasing tensile pre-strain level under the same loading amplitude condition. In this paper, three damage parameters, Delta W-p, W-f, and delta(a)epsilon(a), are respectively used to predict the number of cycles to failure of the tested material with tensile pre-strain effect. In the plot of observed versus predicted cycles, it is observed that most of the data points are located within the bound of factor two for the three damage parameters. Consequently, it is confirmed that the three damage parameters could provide satisfactory predictions for the tested material with a tensile pre-strain effect. (C) 2012 Elsevier Ltd. All rights reserved.