ductileadj.易延展的；柔软的；易教导的ductile damage criteria韧性损伤判据ductile and grey casting球墨和灰口铸铁ductile fracture surface韧性断口ductile metallic material韧性金属材料ductile shear deformation韧性剪切ductile fracture criteria韧性断裂准则Ductile fracture toughness延性断裂韧度ductile cast iron pipeline球墨铸铁管线ductile iron cooling stave球墨铸铁冷却壁ductile fracture mechanism韧性断裂机理