Effect of Friction Stir Processing at High Rotational Speed on Aging of a HPDC Mg9Al1Zn

Friction stir processing (FSP) has confirmed its valuable contribution to refining microstructures and the improvement of mechanical properties for Mg-Al alloys. Reference papers illustrate that post-processing aging treatments enhance hardness, but with the application of a solution heat treatment prior to FSP. In this work, aging was performed at two different temperatures (170 and 300 °C) directly on friction stir processed samples of AZ91 produced using high pressure die casting (HPDC). High rotational speeds of the tools (2500 and 3000 rpm) increases the heat input and the temperature of the plates during the process up to 270 °C. Vickers microhardness (HV) increased by 15–20% in the nugget, compared to the as FSPed condition; moreover, a greater homogeneity of hardness values was found at the higher aging temperature used. The β-Mg17Al12 precipitates are randomly distributed inside grains of the stirred area, while in the thermomechanical affected zone (TMAZ) they have grown in a network similar to the old eutectic. A preliminary investigation of FSPed samples deformed at 300 °C found that an equivalent hardness increase is achievable using hot deformation due to dynamic precipitation; to find local homogeneity in hardness, it is worth performing a final aging.

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Effect of Friction Stir Processing on Microstructural, Mechanical, and Corrosion Properties of Al-Si12 Additive Manufactured Components

Metals ◽

10.3390/met10010085 ◽

2020 ◽

Vol 10 (1) ◽

pp. 85 ◽

Cited By ~ 3

Author(s):

Ghazal Moeini ◽

Seyed Vahid Sajadifar ◽

Tom Engler ◽

Ben Heider ◽

Thomas Niendorf ◽

...

Keyword(s):

Surface Roughness ◽

Surface Quality ◽

Corrosion Behavior ◽

Friction Stir Processing ◽

Micro Hardness ◽

Corrosion Properties ◽

Microstructural Investigation ◽

Friction Stir ◽

Size Refinement ◽

Hardness Values

Additive manufacturing (AM) is an advanced manufacturing process that provides the opportunity to build geometrically complex and highly individualized lightweight structures. Despite its many advantages, additively manufactured components suffer from poor surface quality. To locally improve the surface quality and homogenize the microstructure, friction stir processing (FSP) technique was applied on Al-Si12 components produced by selective laser melting (SLM) using two different working media. The effect of FSP on the microstructural evolution, mechanical properties, and corrosion resistance of SLM samples was investigated. Microstructural investigation showed a considerable grain refinement in the friction stirred area, which is due to the severe plastic deformation and dynamic recrystallization of the material in the stir zone. Micro-hardness measurements revealed that the micro-hardness values of samples treated using FSP are much lower compared to SLM components in the as-built condition. This reduction of hardness values in samples treated with FSP can be explained by the dissolution of the very fine Si-phase network, being characteristic for SLM samples, during FSP. Surface topography also demonstrated that the FSP results in the reduction of surface roughness and increases the homogeneity of the SLM microstructure. Decreased surface roughness and grain size refinement in combination with the dissolved Si-phase network of the FSP treated material result in considerable changes in corrosion behavior. This work addresses the corrosion properties of surface treated additive manufactured Al-Si12 by establishing adequate microstructure-property relationships. The corrosion behavior of SLM-manufactured Al-Si12 alloys is shown to be improved by FSP-modification of the surfaces.

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Aging Behavior of Aluminum Alloy 6082 Subjected to Friction Stir Processing

Crystals ◽

10.3390/cryst8090337 ◽

2018 ◽

Vol 8 (9) ◽

pp. 337 ◽

Cited By ~ 1

Author(s):

Khaled Al-Fadhalah ◽

Fahad Asi

Keyword(s):

Grain Size ◽

Aluminum Alloy ◽

Aging Time ◽

Friction Stir Processing ◽

Aging Temperature ◽

Friction Stir ◽

Average Grain Size ◽

Different Temperatures ◽

Equiaxed Grains ◽

Electron Back Scattered Diffraction

The present work examined the effect of artificial aging on the microstructure, texture, and hardness homogeneity in aluminum alloy AA6082 subjected to friction stir processing (FSP). Aging was applied to FSP samples at three different temperatures (150 °C, 175 °C, and 200 °C) for a period of 1 h, 6 h, and 12 h. Microstructure analysis using optical Microscopy (OM) and Electron Back-Scattered Diffraction (EBSD) indicated that FSP produced fine equiaxed grains, with an average grain size of 6.5 μm, in the stir zone (SZ) due to dynamic recrystallization. Aging was shown to result in additional grain refinement in the SZ due to the occurrence of recovery and recrystallization with either increasing aging temperature and/or aging time. An optimum average grain size of 3–4 μm was obtained in the SZ by applying aging at 175 °C. This was accompanied by an increase in the fraction of high-angle grain boundaries. FSP provided a simple shear texture with a major component of B fiber. Increasing aging temperature and/or time resulted in the formation of recrystallization texture of a Cube orientation. In addition, Vickers microhardness was evaluated for the FSP sample, indicating a softening in the SZ due to the dissolution of the hardening precipitates. Compared to other aging temperatures, aging at 175 °C resulted in maximum hardness recovery (90 Hv) to the initial value of base metal (92.5 Hv). The hardness recovery is most likely attributed to the uniform distribution of fine hardening precipitates in the SZ when increasing the aging time to 12 h.

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Enhanced strength and ductility of high pressure die casting AZ91D Mg alloy by using cold source assistant friction stir processing

Materials Letters ◽

10.1016/j.matlet.2016.12.118 ◽

2017 ◽

Vol 190 ◽

pp. 24-27 ◽

Cited By ~ 8

Author(s):

Nan Xu ◽

Yefeng Bao ◽

Jun Shen

Keyword(s):

High Pressure ◽

Friction Stir Processing ◽

Die Casting ◽

Mg Alloy ◽

High Pressure Die Casting ◽

Friction Stir ◽

Cold Source ◽

Pressure Die Casting ◽

Strength And Ductility

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Design of Functionally Graded Composites through Friction Stir Processing

Journal of Mechanical and Energy Engineering ◽

10.30464/10.30464/jmee.2021.5.2.95 ◽

2021 ◽

Vol 5 (2) ◽

pp. 095-102

Author(s):

Hima Sekhar Sai

Keyword(s):

Cross Sections ◽

Friction Stir Processing ◽

Particle Distribution ◽

Functionally Graded ◽

Friction Stir ◽

Functionally Graded Composites ◽

Surface Composites ◽

Graded Material ◽

Hardness Values ◽

Scanning Electron

An Investigation was conducted to produce Aluminium based Functionally graded material (FGM) composites by Friction stir processing (FSP). A reinforcement strategy featuring the use of Alumina and TiC reinforcements was investigated, where holes were drilled in an Aluminium plate, filled with reinforcements and stirred using FSP. A mathematical model was formulated for positioning of holes in such a manner that the composition of the reinforcements varies from maximum to minimum over a given length. Samples were subjected to various number of FSP passes from one to three with 100% overlap and its influence on particle distribution and homogeneity was studied using Scanning electron microscopy (SEM) at cross sections parallel to the tool traverse direction. A progressive gradient in hardness values was observed for the surface composites at all the passes.

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