TY - GEN
T1 - CHARACTERISTICS OF WHITE LAYERS FORMED IN STEELS BY MACHINING
AU - Akcan, S.
AU - Shah, S.
AU - Moylan, S. P.
AU - Chhabra, P. N.
AU - Chandrasekar, S.
AU - Farris, T. N.
N1 - Funding Information:
This research was supported by the NSF Division of Design, Manufacturing and Industrial Innovation through grant DM1- 9800920, the Caterpillar Corporation and the Center for Collaborative Manufacturing at Purdue University. We are grateful to GE Superabrasives for providing the CBN tools, and to Hardinge Inc. for providing the high precision lathe used in the study.
Publisher Copyright:
© 1999 American Society of Mechanical Engineers (ASME). All rights reserved.
PY - 1999
Y1 - 1999
N2 - 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.
AB - 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.
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U2 - 10.1115/IMECE1999-0742
DO - 10.1115/IMECE1999-0742
M3 - Conference contribution
AN - SCOPUS:85122750750
T3 - ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)
SP - 789
EP - 795
BT - Manufacturing Science and Engineering
PB - American Society of Mechanical Engineers (ASME)
T2 - ASME 1999 International Mechanical Engineering Congress and Exposition, IMECE 1999
Y2 - 14 November 1999 through 19 November 1999
ER -