Faculty Publications

Now showing 1 - 3 of 3

Friction Stir Processing: An Emerging Surface Engineering Technique
(Springer Science and Business Media B.V., 2020) Bajakke, P.A.; Jambagi, S.C.; Vinayak, V.R.; Deshpande, A.S.
Surface modification technologies impart improved surface properties without affecting the bulk properties of the material. The properties could be mechanical, electrical or thermal properties. Until recent past, thermal spray techniques, namely, plasma spraying, high-velocity oxy-fuel coatings and many others widely used for these applications. Friction stir processing (FSP) is a relatively newer technique that uses friction (between two surfaces) as a heat source to form a surface composite on the base alloy. This solid-state process not only refines the given structure but also disperses the reinforcements well within matrix alloy to enhance the surface properties. FSP was earlier employed to low melting point alloys such as aluminum and magnesium-base alloys, but now, with the recent development in tool geometry and tool materials, it can even be effectively used for high melting point alloys like steel and titanium-based alloys. Several process parameters seem to affect temperature and dispersion of reinforcements at the surface. They include rotational speed and traverse speed of the tool, number of passes, cooling medium and the tool geometry. Among these, rotation speed and traversing speed of tool seem to greatly affect the temperature distribution in the plasticized zone formed at the surface. This temperature, in turn, affects the grain refinement and dispersion of reinforcement particles. The present chapter summarizes the effect of these parameters. This chapter also reviews the latest developments in the tool material and its design. Further, their role in augmenting the base alloy properties is also discussed. High hardness, high fracture toughness, chemical inertness and high-temperature strength are few desirable properties of a tool to be used for FSP. In the end, the applicability of FSP as a surface modification technique has been assessed. © 2020, Springer Nature Switzerland AG.
Investigating Mechanical and Corrosion Behavior of Plain and Reinforced AA1050 Sheets Fabricated by Friction Stir Processing
(Springer, 2020) Vinayak, V.R.; Bajakke, P.A.; Jambagi, S.C.; Chavana, C.; Deshpande, A.S.
The present investigations help in improving the bendability and corrosion resistance of AA1050 rolled sheets by selective friction stirring. The processing of AA1050 with a tapered square pin at a tool rotation speed of 1200 rpm yielded the highest strain of 0.345 at ultimate tensile strength compared with 0.054 in as-received material. The identified processing conditions produced an ultimate tensile strength of 89.23 MPa with a toughness of 34.451 × 106 J/m3 and a lower corrosion rate with Icorr of 0.324 × 10?6 A/cm2. Further, processing with a simple tapered circular pin resulted in maximum ultimate tensile strength of 102 MPa with a toughness of 33.990 × 106 J/m3. However, it came at the expense of least resistance to corrosion with Icorr of 4.813 × 10?6 A/cm2. Consequently, the addition of zinc oxide during friction stirring showed a remarkable improvement in corrosion resistance with Icorr of 0.094 × 10?6 A/cm2. Future studies are planned on these lines. © 2020, The Minerals, Metals & Materials Society.
Corrosion behavior of novel AA1050/ZnO surface composite: A potential material for ship hull
(Elsevier B.V., 2020) Bajakke, P.A.; Vinayak, V.R.; Jambagi, S.C.; Deshpande, A.S.
Friction stir processing is one of the effective surface treatments which was employed to process the AA1050 sheets in bare and reinforced condition. The primary objective of the investigation was to expand the applications of AA1050 as a ship hull element in shipbuilding with the least corrosion rate to withstand the harsh marine environment. The base material processed with a rotational speed of 1200 rpm resulted in the highest corrosion rate of 0.173622 mpy. The formation of Al-Fe intermetallic phases was responsible for pitting corrosion. Further, processing by embedding zinc oxide with a rotational speed of 1000 rpm exhibited ~6.68 times improvement in corrosion resistance compared to as-received material. The corrosion rate was found to be 0.003390 mpy. The Al2O3 passive film hinders the initiation and propagation of pits. This study coins a novel composite material and future investigations are emphasized on the same lines. © 2020 Elsevier B.V.

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