采用短棒试样测定了普通灰口铸铁及其补焊焊缝的平面应变断裂韧性ＫＩＣ。结果表明：ＨＴ１００灰口铸铁ＫＩＣ值可达２５ＭＰａｍ，经手工电弧焊或气焊补焊后的ＫＩＣ值明显下降，这在重要铸铁件的补焊过程中应引起注意 The short-rod specimen was used to determine the plane strain fracture toughness KIC of ordinary gray cast iron and its repaired weld. The results show that the KIC value of HT100 gray cast iron can reach 25MPam, and the KIC value after manual arc welding or gas welding repair is obviously decreased, which should pay attention to the welding process of important cast iron parts