Stress-strain model of austenitic stainless steel for pressure vessel design

Design by analysis based on the elastic-plastic method is becoming increasingly important for modern pressure vessels operating under extreme conditions. The stress-strain curve describing material nonlinearity is the primary property that needs to be addressed in this design procedure. Considering that a theoretical model with accuracy and conciseness is always diligently pursued in engineering fields, this study establishes a new stress-strain model of austenitic stainless steel that satisfies such characteristics. The number of parameters required to define this model is decreased compared with the number of parameters in other models, but the accuracy of the former model is still higher than that of the latter. In addition, the empirical parameters used in other models are not needed in the established model, which means that the parameters needed to define this model are determined from the actual strength data of the materials. To verify the advantage of the presented stress-strain model, tensile experiments are conducted on austenitic stainless steel at different temperatures up to 600 & DEG;C, and the experimental stress-strain data are used to compare the presented model and other ones. Type 316H austenitic stainless steel is selected as the test material because it is widely used as heat-resistant steel in engineering fields. Results show that the presented model with few parameters is more accurate than other models in describing the experimental stress-strain data. To further verify the presented stress-strain model's ability and usage convenience, the model is adopted in the elastic-plastic design method of pressure vessels. Simulation of the plastic collapse of a specific vessel under different temperatures is performed, and the limit loads based on different definitions are calculated. Comparison of the limit loads obtained by the experimental stress-strain data reveals that the results of the presented stressstrain model are more accurate than those of the other models. The accuracy and advantage of the presented stress-strain model are thus verified. The model has good engineering application value.