Application Of Small Punch Test To Test Mechanical Properties Of Hastelloy C-276Welded Joint

Since Hastelloy C-276has excellent high temperature mechanical property and corrosion resistance, it is chosen as one of the candidate materials for the fuel cladding in supercritical water reactor. The specimen of Hastelloy C-276is welded by using the electron beam technology. The tensile strengths of the parent metal and the joint are tested by small punch test (SPT). The corresponding load-displacement curves of the specimen are obtained by SPT, which can be used to calculate the mechanical properties. The harnesses of the parent and the joint are measured by the micro-hardness test. Combine with the microstructure observation, the results are discussed. Finite element method is used to simulate the process of SPT to analysis the factors that influence of the results of SPT.The results show that with the increase of specimen’s thickness, yield load and ultimate load of the parent and the joint increase. The simulation result of finite element is consistent with the experimental. Under the condition of the same specimen thickness, yield load and ultimate load of the joint are larger than the parent metal. With the increase of test temperature, yield load and ultimate load of the parent and the joint decrease, but the axial displacement increased gradually. Under the condition of the same test temperature, yield load and ultimate load of the joint are larger than the parent metal. The yield load, ultimate load and maximum axial displacement of the parent metal and joint obtained through the load-displacement curve of SPT are linearly with yield strength, tensile strength and elongation obtained through the conventional tensile test, respectively. The hardness is significantly increased after welding. The strength result of SPT is accord with the micro-hardness test data. Based on the microstructure observation, the enhancements of the hardness and the strength of the joint are due to the lamina structure producing during the welding process. The simulation results of finite element method show that the coefficient of friction and the fixture aperture and the ball diameter can affect the load-displacement curve result.