Analysis on Cracking Reason of GH2036 Nuts

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.