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Effect of near-surface residual stress and microstructure modification from machining on the fatigue endurance of a tool steel

Effect of near-surface residual stress and microstructure modification from machining on the... This study concerns the effect of machining on the fatigue life of an EN X155CrMoV12 tool steel (SAE J438b), with regard to the generation of near-surface residual stress and microstructural modification of the machined surface. Two possible methods for machining tool steels were compared: electro-discharge machining (EDM), a high energy density process, and milling, a more conventional cutting process. Particular attention was given to characterization of the surface roughness, microstructure, and residual stress, using a combination of microstructural analysis, crack observation, scanning electron microscopy (SEM), x-ray diffraction (XRD), and chemical composition changes by energy-dispersive x-ray. A decrease of around 35% in the fatigue limit was observed for the EDM samples, compared with the milled samples. This was attributed to a tensile residual stress state after EDM, combined with significant phase transformation and hydrogen embrittlement. The milled surfaces showed no microstructural transformation or surface cracking and contained compressive residual stresses, all of which contributed to an improved fatigue resistance. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Materials Engineering and Performance Springer Journals

Effect of near-surface residual stress and microstructure modification from machining on the fatigue endurance of a tool steel

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References (34)

Publisher
Springer Journals
Copyright
Copyright © ASM International 2002
Subject
Chemistry; Characterization and Evaluation of Materials; Materials Science; Tribology, Corrosion and Coatings; Quality Control, Reliability, Safety and Risk; Engineering Design
ISSN
1059-9495
eISSN
1544-1024
DOI
10.1361/105994902770343629
Publisher site
See Article on Publisher Site

Abstract

This study concerns the effect of machining on the fatigue life of an EN X155CrMoV12 tool steel (SAE J438b), with regard to the generation of near-surface residual stress and microstructural modification of the machined surface. Two possible methods for machining tool steels were compared: electro-discharge machining (EDM), a high energy density process, and milling, a more conventional cutting process. Particular attention was given to characterization of the surface roughness, microstructure, and residual stress, using a combination of microstructural analysis, crack observation, scanning electron microscopy (SEM), x-ray diffraction (XRD), and chemical composition changes by energy-dispersive x-ray. A decrease of around 35% in the fatigue limit was observed for the EDM samples, compared with the milled samples. This was attributed to a tensile residual stress state after EDM, combined with significant phase transformation and hydrogen embrittlement. The milled surfaces showed no microstructural transformation or surface cracking and contained compressive residual stresses, all of which contributed to an improved fatigue resistance.

Journal

Journal of Materials Engineering and PerformanceSpringer Journals

Published: Dec 1, 2002

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