The pattern of fracture by impact penetration test and tensile fatigue test of thermite welding with stereoscan was observed,and the component of defect with energy spectrum was analyed.

观缺陷主要孔和夹,其中孔由气孔和缩孔组成,夹形态和尺寸分为团簇状夹、锥状夹、粒状夹、积聚夹、丝状夹和混合形夹。