EFFECT OF THERMOMECHANICAL CONTROL PROCESS ON STRENGTHENING OF A 22MN-13CR-5NI AUSTENITIC STAINLESS-STEEL PLATE FOR CRYOGENIC USE

The effect of thermo-mechanical control process (TMCP) on strengthening of a 22Mn-13Cr-5Ni austenitic stainless steel plate for cryogenic use has been investigated by using an intermittent hot compression test. Finish-compression temperature, cooling rate and start-cooling temperature are the factors controlling the recrystallized austenite grain size. The austenite grain becomes finer as the finish-compression temperature decreases and as the cooling rate and the start-cooling temperature increase in the recrystallization region, all of which are effective for strengthening the steel. On the basis of these results, a steel plate of thickness 70 mm was produced on a large scale under the optimum TMCP conditions and the mechanical properties of the steel plate were investigated. The TMCP steel attained a higher 0.2 % yield strength than that of the solution heat-treated (ST) steel at -269°C, though the fracture toughness was slightly reduced. © 1990, The Iron and Steel Institute of Japan. All rights reserved.