Abstract
Friction stir processing (FSP) was used to modify the surface layer of the AZ91 magnesium alloy. The treatment was carried out using a jet cooling nozzle, generating a stream of cold air and enabling intensive cooling of the friction stir processed (FSPed) zone. Single-pass FSP was carried out using a tool rotational speed of 500 rpm and travel speed of 30 mm/min. The treatment was conducted using a truncated cone-shaped tool with a threaded side surface. Strong grain refinement and microstructural changes typical for FSP were found in all the samples. Very fine, equiaxed recrystallized grains dominated in the stirring zone. In the samples modified with the jet cooling nozzle, greater grain refinement was obtained than in the case of naturally cooled material. The average grain size in the surface part of the stirring zone was 1.4 μm and 9 μm in the samples with air-cooling and with natural cooling, respectively. Both the naturally cooled specimen and air-cooled specimen were characterized by a distinctly higher hardness than the base material. The average Vickers hardness in the stirring zone was 91 HV0.1 in the FSPed sample with the air-cooling system and 85.5 HV0.1 with natural cooling, respectively. The average Vickers hardness of the as-cast alloy was 64 HV0.1. Slightly higher wear resistance of the FSPed samples using a jet cooling nozzle was found in relation to the naturally cooled sample. Based on the conducted research, high efficiency of the jet cooling nozzle in cooling the modified zone during friction stir processing was found.
Highlights
Magnesium alloys are modern engineering materials that are used in many industries
The depth of microstructural changes induced by the Friction stir processing (FSP) treatment was analogous in both the analyzed samples, i.e., about 5 ± 0.2 mm; it corresponded to the tool pin length
The cast AZ91 magnesium alloy was subjected to FSP
Summary
Magnesium alloys are modern engineering materials that are used in many industries. The application potential of magnesium alloys is primarily a consequence of its low specific gravity and excellent specific strength, and good machinability and recyclability. The effects of cooling during friction stir processing on the microstructure and properties of the AZ31 magnesium alloy were investigated by Heidarpour et al [22]. Patel et al [26] subjected the AA7075 high-strength alloy to normal and hybrid FSP with different cooling media such as compressed air, water, and CO2 to achieve different cooling rates during the process. Ai et al [10] used friction stir processing to modify the microstructure of the A356 cast aluminum alloy under air-cooling and water-cooling conditions. As part of this work, assessment of the impact of friction stir processing carried out using a jet cooling nozzle on the microstructure and properties of the AZ91 magnesium alloy was undertaken
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: The International Journal of Advanced Manufacturing Technology
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
