Date of Award
2006
Degree Type
Thesis
Degree Name
Master of Engineering Science
Program
Mechanical and Materials Engineering
Supervisor
Prof. Robert Klassen
Abstract
This thesis has two objectives: Firstly, to study the effect of lubricant, temperature, and indenter size on the stress/strain response of Aluminum Alloy AA3104 as determined by spherical indentation. Secondly, to study the composition and the amount of metal transfer between the steel indenter and the indented aluminum alloy AA3104 at various temperatures and lubricant conditions (neat oil and water/oil emulsions). These objectives were achieved with mechanical testing (spherical indentation) and microscopic analyses (optical, SEM and EDX). The indentation load/depth data, at various temperatures and lubricant conditions, obtained from computer-controlled micro-indentation instruments are compared to study the effect of temperature and lubricant on the surface friction between the indenter and the indented aluminum. The average indentation stress and the average indentation plastic strain are calculated from the measured indentation load/depth data. These stress/strain data are compared to uniaxial compression data and correlation expressions are determined that allow the stress/strain flow behaviour of the aluminum alloy to be deduced from spherical indentation tests at room temperature, 1000C and 200°C. The indented aluminum softened as the indentation temperature increased from room temperature to 200°C; this resulted in higher final average indentation depth and easy sticking of aluminum to the indenter surface. The emulsion oil worked as a coolant at high temperatures resulting in lower average final indentation depth. The application of neat oil lubricant at room temperature resulted in a slight increase in the average final indentation depth, and small reduction in the surface friction between the indenter and the indented aluminum. The use of neat oil lubricant at 100°C resulted in higher final average indentation depth. However, at 200°C the use of neat oil lubricant resulted in lower final average indentation depth. Higher indentation stresses and strains were associated with the small indenter, 1 mm diameter, compared to the large indenter, 2.4 mm diameter. The effect of friction between the indenter and the indented aluminum was studied by calculating an adjustment factor A which was found to be dependent upon the iii average indentation plastic strain, temperature, surface friction and the indentation contact area. Optical and SEM images of the steel indenters are examined and studied to understand how the surface friction affects the composition and the amount of metal transfer between the indenter and the indented aluminum. The neat oil lubricant was most effective at 100°C. At temperature below 100°C the lubricants did not significantly reduce the sticking of aluminum to the surface of the steel indenter while at 200°C the lubricants were observed to break down (oxidize) and this also lead to increased sticking of aluminum to the indenter.
Recommended Citation
EL-Madhoun, Thamir F., "Effect of Temperature, Lubricant and Indenter Size on the Stress/Strain Response of Aluminum Alloy AA3104" (2006). Digitized Theses. 5050.
https://ir.lib.uwo.ca/digitizedtheses/5050
