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Open AccessReport10.2172/6298771

Fracture and fatigue properties of 1Cr--Mo--V bainitic turbine rotor steels. Technical report

I. Roman,C. A. Rau,A.S. Tetelman,Kenji Ono-1979-03-01
3

TL;DRAbstract

The deformation, fracture and fatigue properties of 1Cr--Mo--V turbine rotor steel have been evaluated for a wide range of loading conditions and metallurgical structures controlled by melting and heat treatment practice. The mechanical property differences and corresponding metallurgical differences between older, air-melted steels and newer heats that are vacuum degassed were determined. Current vacuum degassing practice improves the tensile ductility, fracture toughness, and fatigue initiation resistance compared to air-melted material by reducing both the size and number of MnS inclusions and the bainite packet size. The yield strength, ultimate strength, and fatigue crack propagation rate are insensitive to these microstructural differences because they are controlled by dislocation substructure. The effects of prior fatique cycling on fracture toughness have been measured, and a model has been developed to predict the effect for various materials and loading conditions. Irrespect

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The deformation, fracture and fatigue properties of 1Cr--Mo--V turbine rotor steel have been evaluated for a wide range of loading conditions and metallurgical structures controlled by melting and heat treatment practice. The mechanical property differences and corresponding metallurgical differences between older, air-melted steels and newer heats that are vacuum degassed were determined. Current vacuum degassing practice improves the tensile ductility, fracture toughness, and fatigue initiation resistance compared to air-melted material by reducing both the size and number of MnS inclusions and the bainite packet size. The yield strength, ultimate strength, and fatigue crack propagation rate are insensitive to these microstructural differences because they are controlled by dislocation substructure. The effects of prior fatique cycling on fracture toughness have been measured, and a model has been developed to predict the effect for various materials and loading conditions. Irrespect

Keywords

Materials scienceDuctility (Earth science)MetallurgyFracture toughnessToughnessFatigue limitUltimate tensile strengthFracture (geology)

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