Nano-indentation has become an important tool in the study of mechanical properties of solids at small length scales, ever since its formulation as a technique in the early 1980s. The small size of an indentation, typically one micrometer or less in surface extent, makes it a potentially attractive tool also for the quantitative study of the characteristics of surface layers in monolithic solids. Here, we report results from a study in which nano-indentation has been combined with taper-sectioning to analyze the mechanical properties of thin surface layers affected by manufacturing processes. The so-called white etching layer (WL) produced in steel surfaces by machining and abrasion is characterized. The WL is found to have a hardness in the range of 11.5–16.2 GPa, which is significantly greater than that of untempered martensite produced by heat treatment processes. These hardness values are close to those measured on steel piano wires. The so-called “burn-layer” produced on ground surfaces of steels is found to have a hardness distribution very similar to that of a white layer, suggesting that the two layers are of the same type. Localized hardening and softening of surface layers, over spatial extents of a few micro-meters, caused by material removal processes are accurately resolved by the combined use of nano-indentation and taper-sectioning. The taper-sectioning/nano-indentation approach is also shown to be a good procedure for characterizing the hardness of PVD-TiN films deposited onto hard metal substrates.

1.
Blau, P. J., 1986, “Methods and Applications of Microindentation Hardness Testing,” In G. F. Vander Voort, ed. Applied Metallography, pp. 123–137, Van Nostrand Reinhold, New York.
2.
Griffiths
,
B. J.
, and
Furze
,
D. C.
,
1987
, “
Tribological Advantages of White Layers Produced by Machining
,”
ASME J. Tribol.
,
109
, pp.
338
342
.
3.
Kahles
,
J. F.
, and
Field
,
M.
,
1967
–68, “
Surface Integrity-A New Requirement for Surfaces Generated by Material-Removal Methods
,”
Proc. Inst. Mech. Eng.
,
182
(
3K
), pp.
31
45
.
4.
Akcan
,
S.
,
Shah
,
S.
,
Moylan
,
S. P.
,
Chhabra
,
P. N.
,
Chandrasekar
,
S.
, and
Yang
,
H. T. Y.
,
2002
, “
Formation of White Layers in Steels by Machining and Their Characteristics
,”
Metall. Mater. Trans.
,
33A
, pp
1245
1254
.
5.
Tarasov
,
L. P.
, and
Lundberg
,
C. O.
,
1949
, “
Nature and Detection of Grinding Burn in Steel
,”
Transactions of the ASM
,
41
, pp.
893
937
.
6.
Zum Gahr, K., 1987, Microstructure and Wear of Materials, Elsevier, New York.
7.
To¨nshoff
,
H. K.
,
Wobker
,
H-G.
, and
Brandt
,
D.
,
1995
, “
Tribological Aspects of Hard Turning with Ceramic Tools
,”
Tribol. Trans.
,
51
(
2
), pp.
163
168
.
8.
To¨nshoff
,
H. K.
,
Wobker
,
H. G.
, and
Brandt
,
D.
, 1995, “Hard Turning-Influences on the Workpiece Properties,” Transactions of the NAMRI/SME, 23, pp. 215–220.
9.
Chou
,
Y. Kevin
, and
Evans
,
Chris J.
, 1998, “Process Effects on White Layer Formation in Hard Turning,” Transactions of NAMRI/SME, 26, pp. 117–122.
10.
Rinehart, J. S., and J., Pearson, 1963, Explosive Working of Metals, Pergamon Press, New York and London.
11.
Zener
,
C.
, and
Hollomon
,
J. H.
,
1944
, “
Effect of Strain Rate Upon Plastic Flow of Steel
,”
J. Appl. Phys.
,
15
, pp.
22
32
.
12.
Baumann
,
G.
,
Fecht
,
H. J.
, and
Liebelt
,
S.
,
1996
, “
Formation of White-Etching Layers on Rail Treads
,”
Wear
,
191
, pp.
133
140
.
13.
Oliver
,
W. C.
, and
Pharr
,
G. M.
,
1992
, “
An Improved Technique For Determining Hardness and Elastic Modulus Using Load and Displacement Sensing Indentation Experiments
,”
J. Mater. Res.
,
7
(
6
), pp.
1564
1580
.
14.
Leslie, W. C., 1981, The Physical Metallurgy of Steels, McGraw-Hill, New York.
15.
Cahn, R. W., and Haasen, P., eds., 1996, Physical Metallurgy, North-Holland, 3 volume encyclopedic set.
16.
Maklin, S., 1989, Grinding Technology: Theory and Applications of Machining with Abrasives, Ellis Horwood Limited, Chichester, UK.
17.
Lake, M., Barimani, C., and Lugscheider, E., 1998, “Fundamentals of Nanoindentation and Nanotribology,” MRS Symposium Proceedings, Vol. 522, pp. 311–316.
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