Analysis of Residual Strain and Stress Distributions in High Speed Milled Specimens using an Indentation Method

Through a proper analysis of residual strain and stress distributions obtained at the surface of high speed milled specimens of AA 6082–T6 aluminium alloy, the performance of an improved indentation method is evaluated. This method integrates a special device of indentation to a universal measuring machine. The mentioned device allows introducing elongated indents allowing to diminish the absolute error of measurement. It must be noted that the present method offers the great advantage of avoiding both the specific equipment and highly qualified personnel, and their inherent high costs. In this work, the cutting tool geometry and high speed parameters are selected to introduce reduced plastic damage. Through the variation of the depth of cut, the stability of the shapes adopted by the residual strain and stress distributions is evaluated. The results show that the strain and stress distributions remain unchanged, compressive and small. Moreover, these distributions reveal a similar asymmetry when the gradients corresponding to conventional and climb cutting zones are compared.

Authors:

• Felipe V. Díaz
• Claudio A. Mammana
• Armando P. M. Guidobono
• Raúl E. Bolmaro

Keywords:

• Residual strain
• residual stress
• high speed milling
• indentation methods
• aluminium alloys.

References:

[1] C. L. Dotson, R. Harlow, and R. L. Thompson, Fundamentals of
Dimensional Metrology. New York: Thompson Delmar Learning, 2003.
[2] M. A. Curtis, and F. T. Farago, Handbook of Dimensional Measurement.
New York: Industrial Press Inc., 2007.
[3] J. A. Bosch (Ed.), Coordinate Measuring Machines and Systems. New
York: Marcel Deckker, Inc., 1995.
[4] J. Lu (Ed.), Handbook of Measurement of Residual Stresses. Lilburn,
Georgia: Fairmont Press Inc., 1996.
[5] R. E. Rowlands, "Residual stresses," in Handbook on Experimental
Mechanics, A. S. Kobayashi, Ed. New Jersey: Prentice-Hall, 1987, pp.
768-813.
[6] P.J. Withers, and H. K. Bhadeshia, "Residual stress" Part 1 -
Measurement techniques, Mater. Sci. Technol., vol. 17, pp. 355-365,
2001.
[7] J.E. Wyatt, and J.T. Berry, "A new technique for the determination of
superficial residual stresses associated with machining and other
manufacturing processes," J. Mater. Proc. Tech., vol. 171, pp. 132-140,
2006.
[8] H. Schulz, High Speed Machining. Munich: Carl Hanser, 1996.
[9] E. M. Trent, Metal Cutting. London: Butterworth/Heinemann, 1991.
[10] R. L. King (Ed.), Handbook of High Speed Machining Technology. New
York: Chapman and Hall, 1985.
[11] A. L. Mantle, D. K. Aspinwall, "Surface integrity of a high speed milled
gamma titanium aluminide," J. Mater. Proc. Tech., vol. 118, pp. 143-
150, 2001.
[12] P. J. Withers, "Residual stress and its role in failure," Rep. Prog. Phys.,
vol. 70, pp. 2211-2264, 2007.
[13] S. P. Timoshenko, and J. N. Goodier, Theory of Elasticity, 3rd edn, New
York: McGraw-Hill, 1970.
[14] F. V. Díaz, R. E. Bolmaro, A. P. M. Guidobono, and E. F. Girini,
"Determination of residual stresses in high speed milled aluminium
alloys using a method of indent pairs," Exp. Mech., vol. 50, pp. 205-215,
2010.
[15] W. Mao, "Recrystallization and grain growth," in Handbook of
Aluminum, vol. 1, Physical Metallurgy and Processes, G. E. Totten, and
D. S. MacKenzie, Ed. New York: Marcel Dekker Inc., 2003, pp. 211-
258.
[16] P. R. Bevington, and D. K. Robinson, Data reduction and error analysis
for the physical sciences, New York: McGraw-Hill, 2002.
[17] A. M. Korsunsky, G. M. Regino, D. P. Latham, H. Y. Li, and M. J.
Walsh, "Residual stresses in rolled and machined nickel alloy plates:
synchrotron X-ray diffraction measurement and three-dimensional
eigenstrain analysis," J. strain analysis, vol. 42, pp. 1-12, 2007.
[18] D. W. Schwach, and Y. B. Guo, "A fundamental study on the impact of
surface integrity by hard turning on rolling contact fatigue," Int. J.
Fatigue, vol. 28, pp. 1838-1844, 2006.