Influence of thermo-mechanical parameters on texture and tensile behavior of friction stir processed Mg alloy (original) (raw)
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Microstructure-Property Relationship for Friction Stir Processed Magnesium Alloy
Advanced Engineering Materials, 2014
Friction stir processing (FSP) of Mg based AE42 alloy was performed under single pass as well as double pass conditions. The evolution of microstructure was investigated using electron back scatter diffraction (EBSD) analysis. EBSD revealed that the grain size and texture varies within the nugget zone of friction stir processed region. The variation of mechanical properties across the nugget region was evaluated using nanoindentation. Hardness and Young's modulus was found to increase along the depth of the friction stir processed specimen. This was attributed to a finer grain structure with increasing depth. The friction stir processed specimen showed higher tendency toward strain hardening compared to as-cast alloy. Understanding microstructure-property relationship paves the way for optimization of FSP conditions and development of advanced functional Mg alloys.
Influence of Process Parameters on Microstructure of Friction Stir Processed Mg AZ31 Alloy
2014
Friction stir processing (FSP) has been developed on the principles of friction stir welding (FSW) as an effective and efficien new method for grain refinement and microstructural modification, providing intense plastic deformation as well as higher strain rates than other conventional severe plastic deformation methods. FSP produces an equiaxed homogeneous microstructure consisting of fine grains, resulting in the enhancement of the properties of the material at room temperature. The objective of the present paper is to examine the influence of friction stir processing (FSP) parameters namely tool rotational speed (RS), tool traverse speed (TS) and tool tilt angle (TA) on the microstructures of friction stir processed AZ31B-O magnesium alloy. This investigation has focused on the microstructural changes occurred in the dynamically recrystallised nugget zone/ stir zone and the thermo mechanically affected zone during FSP. The results presented in this work indicate that all the thre...
Texture and weak grain size dependence in friction stir processed Mg–Al–Zn alloy
The Mg–Zn–Al alloy processed by hot extrusion typically exhibits strong grain size dependence of yield stress. However, the same friction stir processed Mg–Zn–Al alloy samples exhibited much weaker grain size dependence. The high Schmid factor of around 0.3 of the friction stir processed samples is responsible for the low parameters in the Hall–Petch relationship.
MATERIALS TRANSACTIONS, 2013
In this research, Mg9Li2Al1Zn (LAZ-F) magnesium alloy was studied on a friction stir process (LAZ-FSP), and the FSP specimens had stabilized heat treatment (LAZ-FSP-S) to improve the punch-shear properties. LAZ-FSP revealed the network-like structure and particle in the stir zone. Cracks could be found on the subsurface of punch-shear LAZ-F and LAZ-FSP specimens. Notably, specimens with stabilizing heat treatment had no obvious defects on the subsurface after the punch-shear test. It is convincible that stabilizing heat treatment had improved the punch-shear properties of LAZ921. On the other hand, LAZ-FSP shows excellent tensile strength, while LAZ-FSP-S shows a better elongation. Therefore, stabilizing heat treatment at 60°C not only had showed improvements on workability, but also had effectively increased the ductility of magnesium alloy under room temperature.
Journal of Mechanical Science and Technology, 2016
In this paper, the effect of heat treatment and number of passes on microstructure and mechanical properties of friction stir processed AZ91C magnesium alloy samples were investigated. From six samples of as-cast AZ91C magnesium alloy, three plates were pre-heated at temperature of 375°C for 3 hours, and then were treated at temperature of 415°C for 18 hours and finally were cooled down in air. Three plates were relinquished without heat treatment. 8 mm thick as-cast AZ91C magnesium alloy plates were friction stir processed at constant traverse speed of 40 mm/min and tool rotation speed of 1250 rpm. After process, microstructural characterization of samples was analyzed using optical microscopy and tensile and Vickers hardness tests were performed. It was found that heat treated samples had finer grains, higher hardness, improved tensile strength and elongation relative to non-heat treated ones. As the number of passes increased, higher UTS and TE were achieved due to finer grains and more dissolution of β phase (Mg 17 Al 12). The micro-hardness characteristics and tensile improvement of the friction stir processed samples depend significantly on grain size, removal of voids and porosities and dissolution of β phase in the stir zone.
Microstructural Evaluation of Friction Stir Processed AZ31B-H24 Magnesium Alloy
Canadian Metallurgical Quarterly, 2007
The microstructural characteristics in an AZ31B-H24 magnesium alloy after friction stir processing (FSP) were examined. The effects of FSP parameters including forge force and traverse speed on the microstructure were evaluated. It was observed that the grain size increased from about 4 mm in the base metal to about 8 mm at the centre of the stir zone after FSP. The aspect ratio of the grains decreased towards the centre of the stir zone. The changes in the grain size and shape resulted in a drop in micro-indentation hardness from 75 HV in the base metal to about 55 HV at the centre of the stir zone. Increasing the forge force or decreasing the traverse speed increased the grain size due to a greater heat input. It was also observed that the annealing effects (recrystallization and subsequent softening) of FSP were less pronounced with increasing distance horizontally or vertically from the pin tool due to the presence of temperature gradient. Furthermore, the Hall-Petch type relationships between the microhardness and the grain size were found to be valid after FSP.
Friction stir processing of magnesium alloys used in automobile and aerospace applications-A Review
A new microstructural modifications technique was developed by the Welding Institute (TWI) of United Kingdom in 1991 is known as Friction stir processing (FSP). The FSP is a newer technique used for refining and homogenizing the grain structure of metal sheet. Friction stir processing is a great potential in the field of super plasticity and metal matrix composites. Many investigators observed that the FSP greatly enhances super plasticity in many Al alloys. It is a is a solid-state processing technique based on friction stir welding technique in which a specially designed rotating cylindrical tool that comprises of a probe and shoulder. The probe of the tool is inserted into the sheet material while rotating and the shoulder moves over the surface of the sheet, and then traverses in the desired direction. The contact between the rotating probe and the sheet material generate heat due to friction which softens the material and the mechanical stirring caused by the probe, the material within the processed zone undergoes intense plastic deformation yielding a dynamically-recrystallized fine grain microstructure. This paper mainly deals with friction stir processing of magnesium alloys with different reinforcement and different input parameters. The study consist of the effect of different reinforcement addition methods that i.e. groove method and drill hole method on tribological and mechanical properties. The result shows that the addition of reinforcements improves the ultimate tensile strength, strain rate and wear resistance.
Friction stir processing of magnesium alloys used in automobile and aerospace applications
A new microstructural modifications technique was developed by the Welding Institute (TWI) of United Kingdom in 1991 is known as friction stir processing (FSP). The FSP is a newer technique used for refining and homogenizing the grain structure of metal sheet. Friction stir processing is a great potential in the field of super-plasticity and metal matrix composites. Many investigators observed that the FSP greatly enhances super plasticity in many Al alloys. It is a solid-state processing technique based on friction stir welding technique in which a specially designed rotating cylindrical tool that comprises of a probe and shoulder. The probe of the tool is inserted into the sheet material while rotating and the shoulder moves over the surface of the sheet, and then traverses in the desired direction. The contact between the rotating probe and the sheet material generate heat due to friction which softens the material and the mechanical stirring caused by the probe, the material within the processed zone undergoes intense plastic deformation yielding a dynamically-recrystallized fine grain microstructure. This paper mainly deals with friction stir processing of magnesium alloys with different reinforcement and different input parameters. The study consist of the effect of different reinforcement addition methods that i.e. groove method and drill hole method on tribological and mechanical properties. The result shows that the addition of reinforcements improves the ultimate tensile strength, strain rate and wear resistance.
Archives of Metallurgy and Materials, 2016
The samples of the as-cast AM60 magnesium alloy were subjected to Friction Stir Processing (FSP). The effect of FSP on the microstructure of AM60 magnesium alloy was analyzed using optical microscopy and X-ray analysis. Besides, the investigation of selected properties, i.e. hardness and resistance to abrasion wear, were carried out. The carried out investigations showed that FSP leads to more homogeneous microstructure and significant grain refinement. The average grain size in the stirred zone (SZ) was about 6-9 μm. in the thermomechanically affected zone (TMAZ), the elongated and deformed grains distributed along flow line were observed. The structural changes caused by FSP lead to an increase in microhardness and wear resistance of AM60 alloy in comparison to their non-treated equivalents. Preliminary results show that friction stir processing is a promising and an effective grain refinement technique.
Modern Mechanical Engineering, 2017
Friction stir processing (FSP) is an important microstructural alteration process used recently in the engineering field. Grains alteration and hence the mechanical properties of the possessed zone are controlled by the temperature, heating and cooling rate. In this work, AZ31B magnesium samples were friction stir processed in three different cooling conditions like air, water and cryogenic (liquid nitrogen) cooling. 1000 rpm and 60 mm/min were kept constant as tool rotation speed and traverse speed respectively in all the three mediums. The consequence of these conditions on thermal fields, axial force, resulting grain structure and mechanical properties was studied. It is found that the cryogenic treated friction stir processed samples exhibit fine grain structures and hence offer better mechanical properties than the air and water cooled processed samples.