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Effect of Hardness on the Surface Integrity of AISI 4340 Steel
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1986
Year
Materials ScienceEngineeringCorrosionAisi 4340Material MachiningMechanical EngineeringSurface IntegrityTool WearSolid MechanicsResidual StressHardnessChip SegmentationHigh Strength Low Alloy SteelMetal FormingMechanics Of MaterialsMicrostructureMetal Processing
The study examined how hardness influences residual stress in machined AISI 4340 steel surfaces. Chips were analyzed and surface microstructure examined with optical and scanning transmission microscopy. Electron diffraction revealed austenite and untempered martensite in the white layer, while residual stress changes from compressive to tensile as hardness decreases and chip segmentation appears when hardness exceeds Rc 50.
The effect of hardness on the residual stress in the machined surface of AISI 4340 steel was studied. Chips produced during the machining also were examined and the surface structure was investigated using optical microscope and scanning transmission microscope. Reflection electron diffraction study revealed the existence of austenite in the white layer of the machined surface together with untempered martensite. The residual stress near the machined surface or hardened steel is a compressive stress, and it changes to tensile stress as the hardness decreases. Chip segmentation was observed when steel with hardness of over Rc 50 was machined.