CHARACTERISTICS OF WHITE LAYERS FORMED IN STEELS BY MACHINING

S. Akcan, S. Shah, S. P. Moylan, P. N. Chhabra, S. Chandrasekar, T. N. Farris

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

White layers, produced by machining cylinders of AISI 52100, AISl 4340, and AISI M2 steels, are characterized using nanoindentation hardness tests, and microstructural analysis through optical microscopy, transmission electron microscopy and X-ray diffraction. Microstructural observations show that the white layer is composed primarily of martensite. The martensite structure in the white layer is found to have a mean hardness of 12.6 GPa, which is significantly greater than the hardness values of martensite produced by heat treatment or ausforming processes. Furthermore, its grain size is shown to be in the sub-micron range with values ranging. typically, between 50 nm and 500 nm. These two novel characteristics of the white layer martensite distinguish it from martensite structures formed in other operations. The formation of the white layer is promoted by conditions of high cutting speed (100 m/min to 2(X) m/min) and moderate to large values of tool flank wear. Based on these observations, it is hypothesized that white layer formation involves three steps, austenitization of the steel surface, followed by deformation of the high temperature austenite to large plastic strains, and finally, rapid quenching of the austenite by the bulk of the material to form a martensite structure.

Original languageEnglish (US)
Title of host publicationManufacturing Science and Engineering
PublisherAmerican Society of Mechanical Engineers (ASME)
Pages789-795
Number of pages7
ISBN (Electronic)9780791816462
DOIs
StatePublished - 1999
Externally publishedYes
EventASME 1999 International Mechanical Engineering Congress and Exposition, IMECE 1999 - Nashville, United States
Duration: Nov 14 1999Nov 19 1999

Publication series

NameASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)
Volume1999-U

Conference

ConferenceASME 1999 International Mechanical Engineering Congress and Exposition, IMECE 1999
Country/TerritoryUnited States
CityNashville
Period11/14/9911/19/99

All Science Journal Classification (ASJC) codes

  • Mechanical Engineering

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