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

Austenitic stainless steel in pressure vessel industry are using increasingly widely. At the same time, austenitic stainless steel has good plasticity,toughness and low yield ration with the high price. Compared with the conventional design method, using the strain hardening technology to design cryogenic vessels can reduce the vessels'wall thickness and weight, save the vessels'transportation energy consumption and achieve green manufacture and low-carbon economy.Based on many of literatures home and aborad and the company's actual production, the tests of the mechanical properties of domestic austenitic stainless steel 06Cr19Ni10 are done to research the influencing of strain hardening to the material. With the testing results and FEA analysis, the cylinder and spherical shell's strain and stress are got under the strain hardening pressure. Based all of that and standards abroad, the strain hardening of austenitic stainless steel pressure vessels'design method and fabrication process are researched. The main research contents and conclusions are as follows:1. The mechanical properties test of domestic austenitic stainless steel 06Cr19Ni10.First, the mechanical properties of different batches of the steel plate have large difference before and after strain hardening; Second, after the pre-strain controlled by stress, the yield strength can get the expected value; Third, the yield strength is greater with more pre-strain while the plasticity is reduced; Fourth, the treatment of pressure holding makes more strain and can improve the yield strength while reduce the tensile strength and elongation after fracture; Fifth, the elongation after fracture can meet the standard's requirement with the pre-strain below 10%; the toughness can meet the standard's requirement in all the test both in room temperature and low temperature after strain hardening ;2. Stress-strain analysis of the pressure vessel under the strain hardening pressure. Circumferential strain of the vessel can get using the fourth theory of strength according to the truth stress-strain curve from the uniaxial tension test. The same effective stress that produces a strain of 10% in a tensile test produces a circumferential strain 8.7% in a cylinder shell and 5% in a sphere. Under the same strain hardening stress, the sphere makes more circumferential strain as it leads to greater equivalent stress compared with the cylinder. The stress and strain of the vessel with openings are also analyzed: The department far away from the discontinuous area can get the expected results except the ellipsoidal head; there are certain stress concentration in the discontinuous area while the influence is limited3. Researching the design method and putting it into the practice of the strain hardening pressure vessel based on the analysis of the standards abroad. The wall thickness of the vessel is reduced effectively by the strain hardening technology. Also the manufacturing process of the vessel are researched according to the actual production.