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.

观缺陷括孔和夹杂,其中孔由气孔和缩孔组成,夹杂物和尺寸分为团簇状夹杂、锥状夹杂、粒状夹杂、积聚物夹杂、丝状夹杂和混合夹杂。