Evaluation of Tensile Properties of Hydrogen-Charged Zirconium Alloy Materials Based on Small Punch Test Technique

Zr-4 and other two new zirconium alloy materials were subjected to conventional tensile tests at room temperature and 315 degree celsius. The precipitation phase changes caused by composition differences were analyzed based on the calculation results. And the importance of precipitation strengthening mechanism was proposed for the performance improvement of zirconium alloys. The mechanical properties of zirconium alloy were tested for the first time by small punch test (SPT). The coefficient values related to the zirconium alloy material itself were determined in the empirical formula between the conventional tensile test and the small punch test results. The feasibility of the small punch test for the evaluation of the tensile properties of zirconium alloys was verified. Zr-4 and other two new zirconium alloys were hydrogen-charged at 400 degree celsius by gaseous hydrogen permeation, and their mechanical properties were tested by SPT. The results show that the hydrogen-charged Zr alloys have a special phenomenon of & horbar;platform region & Vert; in the plastic instability stage of the load-displacement curve. The morphological characteristics of hydrides were characterized by metallographic analysis and their contents were quantitatively estimated. It is speculated that the difference in the fracture toughness between hydrides and matrix, the special long chain configuration of the hydride phase and its strong orientation have an important correlation with this phenomenon.