某批GH2036螺母在使用过程中, 有8件的表面出现了开裂现象。通过宏观观察、金相检验、硬度测试、断口分析等方法, 确定了螺母开裂的原因。结果表明: 该批零件局部区域存在大量呈带状分布的球型夹杂物, 球型夹杂物的类型为含锰、硅和氧的硅酸盐型夹杂物, 由于夹杂物的存在, 破坏了材料的连续性, 降低了材料的强度, 同时由于夹杂物与基体之间变形速率的差异, 导致了裂纹在棒材成型过程中的扩展, 最后在外力的作用下发生了开裂。

The cracks appeared on the surface of eight nuts of GH2036 alloy during service. Based on macro observation, metallographic examination, hardness testing, fracture analysis and so on, the cracking reason was determined. The results showed that the local area of nuts had a lot of ball inclusions that been scattered chain. Ball inclusions which belonged silicate-type inclusions composed of Mn, Si and O. Because the ball inclusions damaged the continuity of materials, reduced the material strength and the difference of deformation rates between inclusions and matrix, so the cracks propagated in the bar in process of forming, at last the cracking happened under the action of external force.