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MM: Fachverband Metall- und Materialphysik

MM 34: Topical Session Bulk Nanostrucured Materials VII - Mechanical Properties II

MM 34.1: Vortrag

Mittwoch, 28. März 2012, 11:45–12:00, H 0107

The Effect of Severe Plastic Deformation on the Fatigue Behaviour of an Austenitic Stainless Steel — Oliver Renk, •Anton Hohenwarter, and Reinhard Pippan — Erich-Schmid-Institut, Leoben, Österreich

Ultra-fine grained and nanocrystalline materials produced by severe-plastic deformation represent a new class of materials as their properties can be varied over a wide range. Larger specimens now permit, the investigation of mechanical properties of these metals. However, only a few studies on structural materials, such as austenitic steels, exist. In this work the fatigue behaviour of a severely deformed 316L austenitic steel was investigated. By different processing parameters and a post heat treatment, four different ultra-fine grained and nanocrystalline structures were obtained, with grain sizes from 50 nm to 800 nm. The analysis of these different structures should allow a better understanding of the microstructural influence on the fatigue properties. Mechanical tests were conducted on the different severely deformed structures as well as on the coarse grained starting material to show the effect of severe plastic deformation. The main advantage of the ultra-fine grained austenitic structures compared with conventional heavily cold-rolled austenitic steels is, apart from their higher stress levels, their excellent cyclic stability. Fractographic Investigations showed completely different damage and fracture mechanisms of the ultra-fine grained and nano structures. Shear banding and strain localisation in these shear bands play a major role for the damage process during cyclic as well as monotonic loading.