Another Approach to Characterize Particle Distribution during Surface Composite Fabrication Using Friction Stir Processing

Namrata Gangil,Mohammed El-Meligy,Emad Nasr,Abdulaziz El-Tamimi,Sachin Maheshwari,Arshad Siddiquee

doi:10.3390/met8080568

Abstract

Surface composite fabrication through Friction Stir Processing (FSP) is evolving as a useful clean process to enhance surface properties of substrate. Better particle distribution is key to the success of surface composite fabrication which is achieved through multiple passes. Multiple passes significantly increase net energy input and undermine the essence of this clean process. This study proposes a novel approach and indices to relate the particle distribution with the FSP parameters. It also proposes methodology for predicting responses and relate the response with the input parameter. Unit stirring as derived parameter consisting of tool rotation speed in revolutions per minute (rpm), traverse speed and shoulder diameter was proposed. The particle distribution was identified to be achieved in three stages and all three stages bear close relationship with unit stirring. Three discrete stages of particle distribution were identified: degree of spreading, mixing and dispersion. Surface composite on an aerospace grade aluminum alloy AA7050 was fabricated successfully using TiB2 as reinforcement particles. FSP was performed with varied shoulder diameter, rotational speed and traversing speed and constant tool tilt and plunge depth using single pass processing technique to understand the stages of distribution. Significant relationships between processing parameters and stages of particle distribution were identified and discussed.

Highlights

Surface composite (SC) fabrication via friction stir processing (FSP) has become popular over the last decade as it is a clean process and capable of developing superior microstructure and properties.Apart from other materials, aluminum alloys are largely used for SC fabrication by employing various ceramics/hard particle(s) in powder form to provide reinforcement in the ductile interior [1,2]
The individual may contradicting effect of the response, engage with the particle distribution in the material being processed. Studies of such kind are scarcely a unique compound input parameter represented as “unit stirring”, which relates to responses, is reported
FSPare parameters may have fabrication of contradicting effect of 2the response, a unique compound input parameter represented as “unit stirring”, which relates to responses, is defined

Summary

Introduction

Surface composite (SC) fabrication via friction stir processing (FSP) has become popular over the last decade as it is a clean process and capable of developing superior microstructure and properties. Apart from other materials, aluminum alloys are largely used for SC fabrication by employing various ceramics/hard particle(s) in powder form to provide reinforcement in the ductile interior [1,2]. There is a constant urge to improve mechanical properties such as hardness, wear resistance and corrosion resistance in general and strength in particular, in aluminum alloys to further enhance its high specific strength and other associated mechanical properties. Age-hardenable aluminum alloys such as 7xxx series alloys are among the strongest aluminum alloys. Surface composite fabrication may be an Metals 2018, 8, 568; doi:10.3390/met8080568 www.mdpi.com/journal/metals. In precipitation-hardenable alloys, aging imparts maximum allowable strength and aging is the final treatment.

Methods

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Conclusion