Microstructural Modification of AZ91 Magnesium Alloy Using Friction Stir Processing and Carbon Fibers

2017 ◽  
Vol 886 ◽  
pp. 55-58 ◽  
Author(s):  
Shohei Nakagawa ◽  
Angga Afrinaldi ◽  
Toshifumi Kakiuchi ◽  
Yoshihiko Uematsu ◽  
Akio Ohtani ◽  
...  
Keyword(s):  
Grain Refinement ◽  
Carbon Fibers ◽  
Narrow Slit ◽  
Az91 Magnesium Alloy ◽  
Friction Stir ◽  
The Matrix ◽  
Az91 Magnesium ◽  
Hole Defects ◽  
Sever Plastic Deformation ◽  
Cast Magnesium

The microstructure of cast magnesium (Mg) alloy, AZ91, was modified by a friction stir process (FSP) technique. FSP was applied to AZ91 plate with a narrow slit, in which carbon fibers (CFs) were filled. The rotating FSP tool consisting of probe and shoulder could modify the microstructure of the material by sever plastic deformation (SPD) and simultaneously disperse CFs into the matrix. Microstructural observation revealed that sever stirring of material by a tool resulted in the grain refinement due to the dynamic recrystallization and distribution of CFs into the stir zone (SZ). The distribution was not uniform depending on the plastic flow in the SZ, but any worm-hole defects were not formed. Hardness of FSPed AZ91 in the SZ was higher than the as-casted AZ91 because of the grain refinement and distribution of hard CFs.

scholarly journals Microstructure, hardness and wear resistance of AZ91 magnesium alloy produced by friction stir processing with air cooling

2021 ◽  
Author(s):  
Józef Iwaszko ◽  
Krzysztof Kudła
Keyword(s):  
Wear Resistance ◽  
Magnesium Alloy ◽  
Grain Refinement ◽  
Friction Stir Processing ◽  
Vickers Hardness ◽  
Air Cooling ◽  
Az91 Magnesium Alloy ◽  
Friction Stir ◽  
Jet Cooling ◽  
Az91 Magnesium

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.

scholarly journals Microstructure, hardness, and wear resistance of AZ91 magnesium alloy produced by friction stir processing with air-cooling

2021 ◽  
Author(s):  
Józef Iwaszko ◽  
Krzysztof Kudła
Keyword(s):  
Wear Resistance ◽  
Magnesium Alloy ◽  
Grain Refinement ◽  
Friction Stir Processing ◽  
Vickers Hardness ◽  
Air Cooling ◽  
Az91 Magnesium Alloy ◽  
Friction Stir ◽  
Jet Cooling ◽  
Az91 Magnesium

AbstractFriction 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.

Microstructure and Mechanical Behaviors of AZ91 Magnesium Alloy with Thermal Rate Treatment Technique

2011 ◽  
Vol 306-307 ◽  
pp. 471-474
Author(s):  
Yong Zhi Zhou ◽  
Hao Ran Geng ◽  
Yu Jie Sun ◽  
Mei Li
Keyword(s):  
Internal Surface ◽  
Az91 Alloy ◽  
Treatment Technique ◽  
Mechanical Behaviors ◽  
Az91 Magnesium Alloy ◽  
Casting Quality ◽  
Az91 Magnesium ◽  
Cast Magnesium Alloys ◽  
Cast Magnesium

Microstructure and mechanical behaviors of AZ91 cast magnesium alloys with melt superheating and thermal rate treatment technique were studied. Alloy grains thicken at 820°C and refine at 870°C when they contains Mn element and the crucible had no coating on the internal surface. Moreover, the strengthening γ phase is more dispersive and uniform at 870°C. Thermal rate treatment significantly improved the microstructure, mechanical behaviors and casting quality of AZ91 alloy as microstructure of AZ91 alloy reserves some characteristics of the high temperature melt.

Microstructure and Properties of Stir Cast AZ91 Mg Alloy – SiCp Composites

2012 ◽  
Vol 710 ◽  
pp. 365-370 ◽  
Author(s):  
Sujayakumar Prasanth ◽  
Kumaraswamy Kaliamma Ajith Kumar ◽  
Thazhavilai Ponnu Deva Rajan ◽  
Uma Thanu Subramonia Pillai ◽  
Bellambettu Chandrasekhara Pai
Keyword(s):  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Microstructural Characterization ◽  
Casting Process ◽  
Stir Casting ◽  
Tensile Fracture ◽  
Matrix Composites ◽  
Az91 Magnesium Alloy ◽  
The Matrix ◽  
Az91 Magnesium

Magnesium metal matrix composites (MMCs) have been receiving attention in recent years as an attractive choice for aerospace and automotive applications because of their low density and superior specific properties. Using stir casting process, AZ91 magnesium alloy metal matrix composites have been produced with different weight percentages (5, 10, 15, 20 and 25) of silicon carbide particles (SiCp) addition. Microstructural characterization reveals uniform distribution of SiC particles with good interfacial bonding between the matrix and reinforcement. Electrical conductivity and Co-efficient of Thermal Expansion (CTE) measurements carried out on these composites have yielded better properties. Improved mechanical properties such as hardness, ultimate tensile strength, and compressive strength are obtained. The microfracture mechanisms involved during tensile fracture is analyzed and correlated with the properties obtained.

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