ductility transition meaning in English

韧性转变
延性转变

Standard method for conducting drop weight test to determine nil ductility transition temperature of ferritic steels
铁素体钢的无塑性转变温度落锤试验方法
Test method for conducting drop - weight test to determine nil - ductility transition temperature of ferritic steels
测定铁素体钢非塑性转变温度的落锤试验方法
Standard test method for conducting drop - weight test to determine nil - ductility transition temperature of ferritic steels
进行下落重力试验以测定铁素体钢尼尔延展性过渡温度的标准试验方法
The test liquid shall be at a higher temperature than the nil - ductility transition temperature of the material being tested
这句话这样翻译如何：试验液体温度应该高于材料的零塑性变形温度？