Experimental Study on Cryogenic Ratcheting of Pre-Strain Austenitic Stainless Steel SS304

Abstract

Austenitic stainless steel SS304 is often used as the inner container of the Liquefied Natural Gas (LNG) semitrailer tank. Due to excellent cryogenic ductility and strain-hardening effect, pre-strain of austenitic stainless steel is practicable and conducive to achieve lightweight design of this kind of transporting vehicle. In the present work, we focus on the cryogenic ratcheting of pre-strain austenitic stainless steel SS304. The SS304 specimens were cut from as received plates and butt welded plates which are all pre-strained 8% and 12%. With CARE electronic universal testing machine, ratcheting experiments are performed at both ambient temperature and 110K with different mean stresses and stress amplitudes. Ratcheting strains increase with the mean stress and stress amplitude under cryogenic temperature, but much smaller than that at ambient temperature. And it would quickly get shakedown after ratcheting in a few cycles due to the rapid γ-α′ phase transformation under cryogenic temperature. The cryogenic ratcheting strain generally reduces with the pre-strain amount for both parent material specimens and welded specimens. Compared with parent material specimens, weld specimens yield much smaller cryogenic ratcheting strain due to the hardening effect of welding induced initial ferrite with less slipping system.