Modelling Of The Friction Welding Process Between Mild Steel And Alumina

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Date
2011-06
Authors
Seli, Hazman
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Publisher
Universiti Sains Malaysia
Abstract
The heat transfer, mass diffusion and thermo-mechanical mechanisms in friction welding (FW) are not fully understood. In friction welding of two dissimilar materials, two rods are welded together by holding one of them still rotated while the other under the influence of an axial load which creates frictional heat in the interface. This thesis reports a study of the thermal, thermo-mechanical and mass diffusive behaviors of friction welded alumina–mild steel rods with the use of aluminum alloy sheet as interlayer. A series of temperature measurement and energy dispersive X-Ray (EDX) line scan analysis for Al element concentration were carried out near and across the interfaces region and were combined with thermal, diffusion and 3D FEM thermo-mechanical models to acquire material parameters. This work demonstrated the significant change in time-temperature history profiles in alumina rod and the Al element content across the interfaces of alumina-aluminum alloy and steel- aluminum alloy. The bond was obtained through interfacial interlocking and narrow intermetallic phase formation. The finite difference (FD) thermal and diffusion profiles predictions were compared to actual thermocouple and EDX analysis data respectively from welds conducted under identical conditions and were shown to be in fair agreement. A preliminary simulation was made to predict the deformation, stress, strain and temperature distribution during the joining operation using a fully coupled thermo-mechanical FE model. The aluminum alloy metal being rubbed was simulated using a phenomenological Johnson–Cook viscoplasticity material model, which suited for materials subjected to large strains, high strain rates and high temperatures. The highest stress, strain and deformation are found to be within the heat affected of the weld close to the periphery rubbing surface region and correspond to the highest temperature profiles observed.
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Keywords
Friction welded alumina–mild steel rods , use of aluminum alloy sheet as interlayer
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