Experimental and theoretical analysis of the response for 316L stainless steel tubes under pure bending creep and relaxation

In this study, the response sharp-notched 316L stainless steel tubes subjected to pure bending creep and relaxation is experimentally and theoretically studied. Pure bending creep means to bend the specimen to a desired moment and hold that moment for a period of time; pure bending relaxation means to bend the specimen to a desired curvature and hold that curvature for a period of time. From the experimental result for pure bending creep, the curvature and ovalization increase with time until the tube buckles. A higher desired moment leads to higher curvature and ovalization. From the experimental result for pure bending relaxation, the bending moment rapidly decreases with time and becomes a steady value after all. As for the ovalization, the amount increases with time and gradually becomes a steady value. Due to the constant ovalization caused by the constant curvature under pure bending relaxation, the tube does not buckle. Finally, the formulation proposed Lee and Pan [1] is modified for simulating the initial and second stages of the creep curvature-time relationship under pure bending creep, and relaxation moment-time relationship under pure bending relaxation for sharp-notched 316L stainless steel tubes. Through comparing with the experimental finding, the theoretical analysis can reasonably describe the experimental result.