某机械零件机匣体在进行校正时发生断裂。采用化学成分分析和宏、微观断口观察等方法，对断裂件进行了分析。结果表明，断裂件断口上有局部过烧区，且在晶界上形成疏松孔，并伴有严重的氧化。在外力作用下，即发生沿晶界脆性断裂。

Some correction rupture pieces have been analysed in this article by means of the chemical compostion analysis, macroscopic and microcosmic examination of the broken parts. The results showed that there are some overburnt areas on the broken parts and the metal melted along the crystal boundary. If so, the metal will lose its continuity and porous holes are formed in crystal boundary and genreate serious oxidization. Brittlenss rupture will be esay to happen along the crystal boundary when the load was applicd on it and the serious deterioration was appeared on crystal boundary.