How microstructures evolve in heat-treatable aluminum alloys during multi-layer friction deposition is an intriguing question. The current work shows that the process invariably leads to overaging of strengthening precipitates in such materials as alloy 2014. The problem can be overcome using a solution treatment, but it can lead to other problems such as abnormal grain growth. Based on these findings, it appears that the benefits of friction deposition cannot be fully realized in heat-treatable aluminum alloys. © 2013 Elsevier Inc.

Janaki Ram G D

Department of Metallurgical and Materials Engineering

Abnormal grain growth

additive manufacturing

INTRIGUING QUESTIONS

Micro-structure evolutions

OVER-AGING

SOLUTION TREATMENTS

Aluminum alloys

Deposition

Friction

Grain growth

microstructure

tribology

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Materials Characterization

In the present work, a metal-metal composite consisting of aluminum-magnesium alloy AA5083 matrix and nanocrystalline CoCrFeNi high-entropy alloy reinforcement particles in 12 vol% was successfully friction deposited in multiple layers. The layer interfaces or the reinforcement/matrix interfaces showed no brittle intermetallic formation – thanks to the inert nature as well as the high strength and hardness of the high-entropy alloy reinforcement particles. The composite showed significantly higher tensile and compressive strengths as compared to standard wrought-processed alloy AA5083-H112 and offered a much better combination of strength and ductility when compared to conventional aluminum matrix composites reinforced with ceramic particles. The current study establishes friction deposition as a viable technique for additive manufacturing of novel high-performance composite materials. © 2016 Elsevier B.V.

Materials Science and Engineering A

Additive manufacturing of an aluminum matrix composite reinforced with nanocrystalline high-entropy alloy particles

This work offers a fresh perspective on buttering, a technique often considered for fusion welding of dissimilar metals. For the first time, buttering was attempted in solid state using friction deposition. Using this new “friction buttering” technique, fusion welding of two different dissimilar metal pairs (austenitic stainless steel/borated stainless steel and Al-Cu-Mg/Al-Zn-Mg-Cu) was successfully demonstrated. The results show that friction buttering can simplify a tough dissimilar welding problem into a routine fusion welding task. © 2017, The Minerals, Metals & Materials Society and ASM International.

Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science

Friction Buttering: A New Technique for Dissimilar Welding

Friction deposition is one of the promising new techniques for additive manufacturing. In this work, an aluminum matrix composite reinforced with titanium particles was successfully friction deposited. The multi-layer composite friction deposits showed well-bonded layers, very fine grain size, and uniformly distributed titanium particles. While the reinforcement/matrix interfaces showed no reaction products, the layer interfaces showed thin intermetallic bands. These brittle intermetallic bands were found to strongly affect the ductility of the multi-layer composite friction deposits in the build direction. However, the composite friction deposits performed satisfactorily in compression tests as well as in single-layer tensile tests. © 2015 Elsevier B.V.

Friction deposition of titanium particle reinforced aluminum matrix composites

In this work, we explore the possibility of utilizing friction surfacing, an emerging solid-state surface coating process, for layer-by-layer manufacture of three-dimensional metallic parts. One possibility in this regard (single-track friction surfacing) is to utilize friction surfacing for depositing a track or layer of material (sufficiently wide to cover the entire layer area), which is subsequently shaped to its corresponding slice counter using CNC machining. Another possibility (multi-track friction surfacing) is to generate a layer from multiple overlapping tracks of friction surfaced material, which is subsequently shaped as required using CNC machining. In the current work, sound multi-layered deposits in various ferrous materials were realized using friction surfacing in both single-and multi-track approaches. Samples with fully enclosed internal cavities and those consisting of different materials in different layers were also successfully produced. The deposits showed fine-grain wrought microstructures with excellent bonding between individual layers and tracks. Basic mechanical properties of these deposits were found to be at par with their standard processed wrought counterparts. Overall, the current work shows that it is possible to develop a uniquely capable new additive manufacturing process based on friction surfacing. © 2013 Taylor & Francis Group, LLC.

Materials and Manufacturing Processes

Use of friction surfacing for additive manufacturing

Friction surfacing involves complex thermo-mechanical phenomena. In this study, the nature of dynamic recrystallization in friction surfaced austenitic stainless steel AISI 316L coatings was investigated using electron backscattered diffraction and transmission electron microscopy. The results show that the alloy 316L undergoes discontinuous dynamic recrystallization under conditions of moderate Zener-Hollomon parameter during friction surfacing. © 2012 Elsevier Inc. All rights reserved.

Dynamic recrystallization in friction surfaced austenitic stainless steel coatings

Commercially pure aluminium was subjected to friction stir processing (FSP) to study the microstructure developed and its effects on the mechanical properties. Friction stir processing refined the grain size to 3. μm in a single pass from the starting coarse grain size of 84. μm. Electron backscattered diffraction (EBSD) results showed occurrence of dynamic recrystallization and also revealed existence of different orientations within the stir zone and across the transition zone. Transmission electron microscopy (TEM) revealed fine grains with well defined boundaries. The arrangement and absorption of dislocation into the sub-grain boundaries, formed by dynamic recovery, was also revealed by TEM. The yield strength of the material was improved by a factor of 2.4 after FSP owing to grain refinement. The most important feature of the friction stir processed material was that even after this significant improvement in strength there was little loss of ductility. The hardness also improved by 34% with the peak hardness being observed towards the advancing side. © 2012 Elsevier B.V.

Effect of friction stir processing on microstructure and mechanical properties of aluminium

Friction surfacing is a novel solid-state surfacing process with several advantages over conventional weld overlay processes. In this work, the corrosion behavior of AISI 316L stainless steel coatings made using friction surfacing and manual metal arc welding processes was comparatively evaluated. Friction surfaced coatings exhibited superior general and pitting corrosion resistance compared to manual metal arc coatings, while both the coatings were found to be immune to intergranular corrosion. Compared to alloy 316L bulk material, friction surfaced coatings showed better pitting corrosion resistance, but considerably lower general corrosion resistance. © 2012 Elsevier Ltd.

Corrosion Science

Corrosion performance of AISI 316L friction surfaced coatings

Infrared (IR) thermography was used to measure thermal profiles in the coating, consumable rod, and substrate during friction surfacing. A sudden raise followed by a steady state in thermal profile was observed and attributed to viscous heat dissipation during plastic deformation. The retreating side of the coating experienced higher temperature compared to the advancing side, indicating that the hot plasticized metal is carried from the advancing side to the retreating side. © 2011 The Minerals, Metals &amp; Materials Society and ASM International.

Journal	Materials Characterization
ISSN	10445803
Open Access	No