Study Of Strengthening Process And Design On Strain Hardening Austenitic Stainless Steel Pressure Vessels

This paper is supported by National Science and Technology Ministry, "Eleventh Five-Year", "863" key project in the areas of advanced manufacturing technology, "The design, manufacture and maintenance of significant pressure equipment under extreme conditions"(2009AA044801). Based on referring to a large number of literatures and standards, for the domestic austenitic stainless steel 0Cr18Ni9, through experimental study and theoretical analysis, this paper has studied: influence on the macroscopic mechanical properties of the strain hardening process; depth study of the strain hardening behavior, and its mathematical model; qualitative analysis on evolution of the internal organization of material during strain hardening process; quantitative analysis on of phase evolution inside the material during strain hardening process; preliminary design study of strain hardening austenitic stainless steel pressure vessel. This article has drew the following conclusions:⑴.As the deformation increases, strength index increases substantially, and plasticity, toughness reduce accordingly. Even after 12% deformation of the pre-strengthened, material ductility and toughness still have a very good reserve; Under quasi-static, with a acceleration of deformation rate, material changes on all index slightly, the effect on the macroscopic mechanical properties of deformation rate is not great.⑵.As the deformation increases, the strain hardening capacity gradually weakes; And under quasi-static, The influence on the strain hardening capacity of deformation rate during strengthening process is minimal.⑶.During the process of strengthening, with a acceleration of strain rate, the strength is higher, strain rate sensitivity is stronger.⑷.As the deformation increases, the material microhardness gradually increases; the upward trend is similar with the increasement in yield strength of deformation.⑸.With the increase of deformation, slip lines inside the material gather obviously, and subsequently produce a certain amount of deformation twins and a small amount of strain induced martensite; Under quasi-static, with the deformation rate speeds up, the internal organization morphology similitude, slip line a little dense.⑹.With the increase of deformation, austeniteγphase content decreases linearly, the strain induced martensiteα' phase content increases gradually, the strain inducedεmartensite phase content firstly increases and then decreases. In the small strain stage,γphase transform to phaseα',εphase together; In the large strain stage, the part of theεphase transform toα' phase. Under quasi-static, with a acceleration of strain rate, strain induced martensite content decreases gradually.