Extrusion of Aluminium Alloys / T. Sheppard

 

 

 

 

 

 

 

SELECTED CONTENTS:

Introduction

  • The thermomechanical process
  • Direct and indirect extrusion
    – Direct extrusion
    – Indirect extrusion
  • Extrusion of rods and solid shapes
  • Extrusion of hollow sections
  • The extrusion press
    – Direct presses
    – Indirect presses

Continuum principles

  • Yielding and ductility
  • Constitutive equations
  • The extrusion pressure
  • The friction coefficient
  • Temperature models
    – Temperature profile in the heated billet
    – Heat balance in extrusion
    – Finite-element modeling predictions
    – Thermal balance during extrusion predicted by integral profile techniques
  • Diffusion

Metallurgical features affecting the extrusion of aluminium alloys

  • Aluminium-alloy systems
  • The DC cast state
  • Homogenization
    – Metallurgical consideration of homogenization
  • Thermal activation
  • Recovery and recrystallization
    – Dynamic recovery and dynamic recrystallization
    – Microstructure
  • Recrystallization and layer thickness after solution soaking
  • Quench sensitivity

Extrusion processing

  • Introduction
  • The Zener-Hollomon parameter and flow stress
    – Flow stress
    – Theoretical considerations
    – Comparison of compression and torsion in material assessment
  • Material flow in extrusion
    – The three types of flow
  • The pressure/displacement diagram
  • The strain rate during extrusion
  • Extrusion pressure – practical considerations
    – The effect of friction
    – The effect of the temperature-compensated strain rate
    – The effect of section shape
  • Surface quality considerations
  • Process-structure relationships
  • Recrystallization
    – Structure after extrusion
    – Volume fraction recrystallization in the F-temper and after solution soaking
  • The relationship between process parameters and properties
  • Material flow and inhomogeneity – structural considerations
    – Development of structure in the extrusion container
    – Substructural considerations
    – Extrudate structure
    – Subgrain size
    – Development of dislocation structure related to peak: pressure
  • Press quenching and press solutionizing
    – Introduction
    – Metallurgical aspects
    – Technological problems
  • Limit diagrams

Homogenization and extrusion conditions for specific alloys

  • Introduction
  • lXXX alloys
  • 2XXX alloys
  • 3XXX alloys
  • 4XXX alloys
  • 5XXX alloys
  • 6XXX alloys
  • 7XXX alloys
    – AI-Zn-Mg alloys
    – AI-Zn-Mg-Cu alloys
  • Aluminium-lithium alloys
  • Extrudability, limit and productivity diagrams
    – Extrudability
    – Limit diagrams
    – Productivity diagrams

Processing of 6XXX alloys

  • Homogenization
    – General principles of heat treatment
  • Alloys for specific applications
    – High extrudability, general purpose alloys
    – Medium-strength alloys
  • Factors affecting quench sensitivity
    – Cooling rate
    – Recrystallization inhibitors
    – Toughness
    – Structural sensitivity
    – Quench sensitivity in welding
  • Surface problems and surface generation
    – Introduction
    – Surface features
    – Extrusion topology (limit) diagrams
    – Summary
  • Alternative metallurgical diagrams
    – Possible phase transformations
  • Texture
  • Extrusion defects
    – Metallurgical factors affecting press productivity
    – Recovery related defects
    – Metallurgical defects visible after anodizing

Plant utilization

  • Introduction
  • The modem extrusion plant
    – The extrusion press
    – Ancillary equipment
    – The extrusion process and parameter optimizing
  • Press requirements
    – Reliability
    – Mechanics
    – Hydraulics
    – Control and monitoring
  • Isothermal extrusion
    – Process optimization
    – Features required in a comprehensive process optimization
    – Results of process optimization
  • Expert systems
    – An expert system applied to an extrusion press
    – A typical system description
  • Aspects of die design and correction
    – Die stack considerations
    – Die design steps
    – Process factors to consider before modifying the die
  • Tool failure
    – Characteristics
    – Preventative measures
  • Scrap losses
    – Extrusion losses
    – Billet scrap
  • Extrusion control in manufacturing profiles of complex shapes
    – Classification of complex shapes
    – Improvement of billet quality
    – Extrusion press alignment
    – Extrusion condition
  • Product tolerance
    – Die section
    – Extrusion section
    – Billet section
    – Extrusion conditions
    – Improvements in yield