基于小冲杆试验技术评估充氢锆合金材料的拉伸性能

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

对Zr-4以及其它2种新型锆合金材料在室温、315℃条件下进行常规拉伸试验,结合计算结果分析了成分差异造成的沉淀相改变,提出了析出强化机制对于锆合金性能提升的重要意义。首次利用小冲杆试验对锆合金原样的力学性能进行测试,该工作确定了常规拉伸试验与小冲杆试验结果之间的经验公式中与锆合金材料本身相关的系数数值,验证了小冲杆试验用于锆合金拉伸性能评估的可行性。利用气相渗氢法在400℃对Zr-4以及其它2种新型锆合金进行充氢处理,并利用小冲杆试验对锆合金充氢试样的力学性能进行测试。结果表明,充氢锆合金在载荷-位移曲线的塑性失稳阶段出现“平台区”特殊现象。对该现象进行探究,用金相分析表征了氢化物的形貌特征并对其含量进行了定量估算,推测氢化物与基体断裂韧性上的差异、氢化物相特殊的长链构型以及强取向性与这一现象有着重要关联。

Zr-4 and other two new zirconium alloy materials were subjected to conventional tensile tests at room temperature and 315℃.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℃ 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"platform region"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.