Experimental study on cyclic hardening characteristics of structural stainless steels

Abstract

This paper studies the cyclic hardening characteristics of commonly used structural stainless steel types and grades including austenitic stainless steel grades S30408 and S31608 (equivalently to EN 1.4301 and EN 1.4401) as well as duplex stainless steel grade S22053 (equivalently to EN 1.4462) under tension-compression cyclic loading. A total of twenty-four monotonic loading tests and thirty-six cyclic loading tests were performed and two different cyclic loading protocol types were selected, namely cyclic ascend (CA) loading and cyclic constant (CC) loading with strain amplitudes ranging from ±0.5% to ±5%. Specimens with plate thicknesses of 6 mm and 8 mm were tested. The test results indicate that the cyclic hardening/softening behavior of the three grades of structural stainless steel generally shows obvious strain amplitude dependence and unsaturation before fracture under large strain amplitudes, which are significantly different from carbon steel. Meanwhile, there is a huge difference between the cyclic skeleton curves and the monotonic constitutive curves for different stainless steel grades. The effects of strain amplitude, stainless steel grade and loading history on the cyclic hardening/softening characteristics have been thoroughly studied. It should be noted that the seismic performance of stainless steel structures is greatly affected by the loading history. From the viewpoint of the seismic design of stainless steel structures, this paper proposes an equation to predict the maximum cyclic hardening degree at various strain amplitudes under constant amplitude loading.