Strength and Toughness of 12Cr-12Ni-10Mn-5Mo Steel for Cryogenic Structural Application

Abstract

It is well known that austenitic stainless steels are non-magnetic and have good toughness and high strength at low temperature. In this study, the effects of alloying elements such as molybdenum, manganese and nitrogen on the strength and toughness of austenitic steels and the mechanical properties of their large forgings were investigated at low temperature. The obtained results are summarized as follows.
(1)Molybdenum is effective for improving strength and toughness of austenitic steel at low temperature.
(2)A 12Cr-12Ni-10Mn-5Mo steel was developed as a modification of SUS316LN for cryogenic structural material.
(3) At low temperature, the grain refinement is effective for increasing yield strength and the reduction of inclusions is effective for increasing toughness.
(4)An industrial scale forged plate of the newly developed steel was manufactured from a 6 t ESR ingot. The 140 mm thick plate showed very homogeneous mechanical properties through the thickness.