Local heat generation and material flow in friction stir welding of mild steel assemblies

Daniel Micallef, Duncan Camilleri, Athanasios Toumpis, Alexander Galloway, Larbi Arbaoui

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

In friction stir welding (FSW), assemblies are joined by means of practising, shearing and stirring non-molten material. The heat generation is directly related to the viscous behaviour of plasticised material, through coupled Navier-Stokes thermo-fluid flow stress equations. A significant amount of research has been conducted on aluminium FSW but studies on mild steel assemblies are limited. The aim of this work is to understand the influence of the tool rotational and traverse speed on the resulting material stir zone shape and the heat power generated in FSW of mild steel assemblies. A numerical and experimental approach is adopted in this study. Material visco-plastic properties are primarily established experimentally and are then applied to a computational fluid dynamics (CFD) model through user defined material flow stress constitutive laws. The model was further validated through a series of thermocouple and macrograph measurements and later on used to fulfil the aims of this work. This study identifies that the total heat generated for different welding parameters follows a non-linear variation with radial and angular tool position. These results provide a platform for the accurate definition of heat flux inputs and thermal strains to global thermo-elasto-plastic models, replacing more simplified linear specifications currently used in the literature.
LanguageEnglish
Pages586-602
JournalProceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications
Volume230
Issue number2
Early online date17 Apr 2015
DOIs
Publication statusPublished - 6 Apr 2016

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Friction stir welding
Heat generation
Carbon steel
Plastic flow
Plastics
Thermocouples
Aluminum
Shearing
Heat flux
Flow of fluids
Enthalpy
Dynamic models
Computational fluid dynamics
Welding
Specifications

Keywords

  • friction stir welding
  • mild steel
  • visco-plasticity
  • computational fluid dynamics (CFD)
  • heat generation
  • material flow

Cite this

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abstract = "In friction stir welding (FSW), assemblies are joined by means of practising, shearing and stirring non-molten material. The heat generation is directly related to the viscous behaviour of plasticised material, through coupled Navier-Stokes thermo-fluid flow stress equations. A significant amount of research has been conducted on aluminium FSW but studies on mild steel assemblies are limited. The aim of this work is to understand the influence of the tool rotational and traverse speed on the resulting material stir zone shape and the heat power generated in FSW of mild steel assemblies. A numerical and experimental approach is adopted in this study. Material visco-plastic properties are primarily established experimentally and are then applied to a computational fluid dynamics (CFD) model through user defined material flow stress constitutive laws. The model was further validated through a series of thermocouple and macrograph measurements and later on used to fulfil the aims of this work. This study identifies that the total heat generated for different welding parameters follows a non-linear variation with radial and angular tool position. These results provide a platform for the accurate definition of heat flux inputs and thermal strains to global thermo-elasto-plastic models, replacing more simplified linear specifications currently used in the literature.",
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