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.

观缺陷主要包和夹,其中由气和缩组成,夹物按形态和尺寸分团簇状夹、锥状夹、粒状夹、积聚物夹、丝状夹和混合形夹。