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Abstract This study analyzed a crack in a scrapped 18MnNiMo5 80-tonne shell. The root cause of crack formation was the low fracture toughness caused by a combination of a high… Click to show full abstract
Abstract This study analyzed a crack in a scrapped 18MnNiMo5 80-tonne shell. The root cause of crack formation was the low fracture toughness caused by a combination of a high hydrogen content and phosphorous segregation, caused by an inappropriate heat treatment. Cracking initiated on MnS inclusion clusters enabled by hydrogen desorption at the MnS/matrix interfaces. Crack propagation was due to the internal hydrogen pressure causing the crack tip stress intensity factor to exceed the locally-reduced fracture toughness. This new hydrogen induced cracking (HIC) mechanism can be designated as Hydrogen Induced Localised Damage (HILD). Appropriate process controls can eliminate such defects.
Journal Title: Engineering Failure Analysis
Year Published: 2019
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