Effect of grain refinement on mechanical properties and sliding wear resistance of extruded Sc-free 7042 aluminum alloy

• The optimum amounts of grain refiners were selected 0.03 wt.% Ti and 0.3 wt.% Zr.
• Al–5Ti–1B is more effective than Al–15Zr in reducing the grain size.
• The microstructure of refined alloy reveals rosette-like primary α-Al solid solution.
• The addition of grain refiners was effective to enhance tensile properties of alloy.
• The formation of TiB2 and Al(Zr,Ti)3 particles improve the wear resistance of refined alloys.

The present study deals with an investigation on dry sliding wear behavior of grain refined Sc-free 7042 aluminum alloy by using a pin-on-disc wear test machine. Al–5Ti–1B and Al–15Zr master alloys were used as grain refining agents. The optimum amounts of added Ti and Zr in the alloy were found to be 0.03 wt.% and 0.3 wt.%, respectively. Extrusion was carried out and T6 heat treatment ware applied for all rod specimens before testing. Significant improvement in mechanical properties was obtained with the addition of grain refiners. The worn surfaces were characterized by energy dispersive X-ray spectrometry microanalysis. Results showed that the wear resistance of unrefined alloy increased with the addition of both grain refiners. Furthermore, the worn surface studies showed a mixed type of wear mechanisms; delaminating, adhesive and abrasive which took place at higher applied load.