Welding Aluminum— Questions and Answers


A Practical Guide for Troubleshooting Aluminum Welding-Related Problems

By Tony Anderson




Chapter 1—The Advancement of Aluminum within the Welding Fabrication Industry and its Many Product Design Applications

1.1 Introduction

1.2 Automotive Industry

1.3 Shipbuilding

1.4 Recreation and Sporting Equipment

1.5 Transportation and Containers

1.6 Defense and Aerospace

1.7 Conclusion

Chapter 2—What is the History of Aluminum and Aluminum Welding?

2.1 Introduction

2.2 The Story Behind the Metal

2.3 Developments in Welding Aluminum

2.4 The History of Heliarc Welding (Gas Tungsten Arc Welding)

2.5Gas Welding (Oxyacetylene Welding)

2.6 Stick Electrode Welding (Shielded Metal Arc Welding)

2.7 Conclusion

Chapter 3—Aluminum Alloys and Metallurgy

3.1 The Aluminum Alloy Designation System

    • Introduction
    • Wrought Alloy Designation System
    • Cast Alloy Designation
    • The Aluminum Temper Designation System
    • Aluminum Alloys and Their Characteristics
    • 1xxx Series Alloys
    • 2xxx Series Alloys
    • 3xxx Series Alloys
    • 4xxx Series Alloys
    • 5xxx Series Alloys
    • 6xxx Series Alloys
    • 7xxx Series Alloys
    • Conclusion

3.2 What is the Affect of Arc Welding on the Heat-Affected Zone (HAZ) of Aluminum Alloys?

    • Introduction
    • The Various Types of Aluminum Alloys
    • The Principal Effects of Alloying Elements in Aluminum
    • Pure Aluminum 1xxx
    • Copper (Cu) 2xxx
    • Manganese (Mn) 3xxx
    • Silicon (Si) 4xxx
    • Magnesium (Mg) 5xxx
    • Magnesium and Silicon (Mg2Si) 6xxx
    • Zinc (Zn) 7xxx
    • How Aluminum Alloys Obtain Their Strength
    • Strain Hardening
    • Heat Treatment
    • The Affect of Arc Welding on the Heat-Affected Zone
    • Nonheat-Treatable Alloys
    • Heat-Treatable Alloys
    • Conclusion

3.3 Is There a Filler Alloy that Can be Used to Weld All Aluminum Base Alloys, and How Do I Weld Aluminum Alloys 7075 and 2024?

    • A Filler Alloy for All Aluminum Base Alloys
    • Welding 2024 and 7075
    • Conclusion

3.4 What are the Differences Between the Heat-Treatable and NonheatTreatable Aluminum Alloys?

    • Understanding the Basic Differences Between Heat-Treatable and Nonheat-Treatable Aluminum Alloys
    • Nonheat-Treatable Aluminum Alloys
    • Heat-Treatable Aluminum Alloys
    • How Does the Type of Material, Heat-Treated or Nonheat-Treated, Affect the Completed Strength of the Weld?
    • Conclusion

3.5 What are the Alloying Elements in Aluminum Alloys?

    • The Addition of Alloying Elements to Aluminum
    • The Principal Effects of Alloying Elements in Aluminum
      • Copper (Cu) 2xxx
      • Manganese (Mn) 3xxx
      • Silicon (Si) 4xxx
      • Magnesium (Mg) 5xxx
      • Magnesium and Silicon (Mg2Si) 6xxx
      • Zinc (Zn) 7xxx
      • Iron (Fe)
      • Chromium (Cr)
      • Nickel (Ni)
      • Titanium (Ti)
      • Zirconium (Zr)
      • Lithium (Li)
      • Lead (Pb) and Bismuth (Bi)
    • Conclusion

3.6 What are Weldable and Unweldable Aluminum Alloys?

    • The Definition of the Tern “Unweldable”
    • Difficult-to-Weld Alloys
    • Coherence Range
    • The 2xxx-Series Alloys (Al-Cu)
    • The 7xxx-Series Alloys (Al-Zn)
    • Conclusion

3.7 How do I Establish the Strengths of Aluminum Alloys, Base Material, Welds and Filler Alloys?

    • Aluminum Base Alloy Strength
    • Aluminum Filler Metal Strength and As-Welded Aluminum Joint Strength
    • The AWS Filler Metal Classification System for Aluminum
    • Conclusion

3.8 What is the Affect of Natural Aging on 6061 Aluminum Base Alloy?

    • The Heat-Treated Condition of the Base Alloy
    • The Affect of Natural Aging After Solution Heat Treatment
    • The Affect of Aging on the HAZ
    • Heat-Treatable Filler Alloy
    • Conclusion

3.9 What is the Affect of Elevated Service Temperature on 6xxx Series Aluminum Alloys?

    • What is the Reason for this Drop in Hardness and Will the Hardness Drop Further?
    • What is the Phenomenon Behind the Hardness Drop After Heating?
    • Will the Hardness Drop Affect Surface Roughness (Pitting, etc.)?
    • Conclusion

3.10 What is Anodized Aluminum?

    • What is Anodizing?
    • How is it Performed?
    • Different Types of Anodizing
      • Type I—Chromic Acid Anodizing
      • Type II—Sulfuric Acid Anodizing
      • Type III—Hardcoat Anodizing
    • Sealing
    • Welding on Anodized Aluminum
    • Anodizing Material After Welding
    • Conclusion

3.11 Can Stress Corrosion Cracking (SCC) Affect the 5xxx Series Aluminum Alloys?

    • What is Stress Corrosion Cracking (SCC)?
    • The Susceptibility of the 5xxx Series Aluminum-Magnesium Alloys to SCC
    • Is SCC a Problem when Using the 5xxx Series Aluminum Alloys?
    • Conclusion

3.12 What are the Primary Considerations When Evaluating the Design Strength of Welded Aluminum Structures?

    • The Reduction in Strength of the Base Material After Welding
    • The Effect of Filler Alloy Selection on the Strength of Fillet Welds
    • Conclusion

3.13 What Can be Done to Restore the Lost Strength in Aluminum Weldments After Welding?

    • The Affect of Arc Welding on Material Temper
      • Nonheat-Treatable Alloys
      • Heat-Treatable Alloys
    • Options Available for Postweld Treatment
      • Nonheat-Treatable Alloys
      • Heat-Treatable Alloys
      • The –T6 Temper
      • The –T4 Temper
    • Conclusion

3.14 What are the Types of Heat Treatment Used on Aluminum Alloys and How Do They Influence Manufacturing Procedures?

    • Solid-Solution Hardening
    • Precipitation Hardening
    • Annealing
    • Stabilizing
    • Stress-Relieving
    • Refrigeration
    • Influence of Heat Treatment on Manufacturing Procedures
      • Welding
      • Forming and Machining
    • Conclusion

3.15 Why are Aluminum Alloys Suitable for Low Temperature Application and Why are There No Impact Toughness Requirements for Aluminum Filler Alloys?

    • Cryogenic Applications
    • Test Data Available for Low Temperature Applications
    • Conclusion

3.16 How Can I be Assured that I am Using the Correct 5xxx Series Aluminum Alloy for Marine Applications and Thereby Prevent Sensitization and Intergranular Corrosion?

    • The Problem
    • The Action Taken to Prevent Reoccurrence
    • More About the B 928 Standard
    • Conclusion

3.17 Where Can I Find Technical Information and Training on Aluminum Welding?

    • Useful Textbooks
    • Training Programs for Aluminum Welding
    • Conclusion

Chapter 4—Aluminum Filler Alloys

4.1 Filler Alloy Selection for Aluminum Welding

    • Introduction
    • Ease of Welding
    • Critical Chemistry Ranges
      • Aluminum/Silicon Alloys—4xxx Series
      • Aluminum/Copper Alloys—2xxx Series
      • Aluminum/Magnesium Alloys—5xxx Series
      • Aluminum/Magnesium/Silicon Alloys—6xxx Series
    • Crack Sensitivity
      • Coherence Range
      • The 2xxx Series Alloys (Al-Cu)
      • The 7xxx Series Alloys (Al-Zn)
    • Groove Weld Tensile Strength
    • Ductility
    • Corrosion Resistance
    • Service Temperature
    • Postweld Heat Treatment
    • Conclusion

4.2 What Filler Alloy Should be Used to Weld 6061?

    • How to Choose the Best Filler Alloy
    • Making the Choice
    • Conclusion

4.3 What are the Advantages of 4047 Filler Alloy over 4043?

    • The Difference Between 4043 and 4047 Filler Alloys
    • Conclusion

4.4 What is the Correct Filler Alloy for Welding 5083 Base Alloy, and is the Filler Alloy I am Using the Reason Why I am Failing the Guided-Bend Tests?

    • What is the Most Appropriate Filler Alloy?
    • Why Did the Welded Samples Fail the Guided-Bend Test?
    • Reasons Why a Welded Sample May Fail the Guided-Bend Test
      • Discontinuities in the Welded Joint
      • Using an Incorrect Testing Fixture
      • Improper Sample Preparation
    • Conclusion

4.5 Should I Use 4043 or 5356 Filler Alloy?

    • Choosing Between 4043 and 5356
    • Conclusion

4.6 Are the 4xxx Series Aluminum Alloys Heat-Treatable Alloys or Nonheat-Treatable Alloys?

    • Postweld Heat Treatment
    • Conclusion

4.7 Which Aluminum Filler Alloys are Suitable for Sustained High-Temperature Service?

    • Introduction
    • Evaluation of Most Appropriate Filler Alloy
      • Filler Alloy ER4643
      • Filler Alloy ER4043
      • Filler Alloy ER4047
      • Filler Alloy ER5554
    • Conclusion

4.8 Filler Alloy Selection Chart

Chapter 5— Welding Discontinuities and Weld Testing

Chapter 6— Equipment, Welding Processes, and Welding Procedures 

Chapter 7—The Common Welding Processes 

7.1 Introduction to the GTAW and GMAW Processes 

7.2 Gas Tungsten Arc Welding of Aluminum Alloys 

7.3 Gas Metal Arc Welding of Aluminum Alloys 

7.4 Brazing and Soldering of Aluminum Alloys 

  • Brazing 
  • Brazeability 
  • Filler Metals 
  • Fluxes 
  • Chloride Fluxes 
  • Fluoride Fluxes 
  • Torch Brazing 
  • Furnace Brazing 
  • Induction Brazing 
  • Dip Brazing 
  • Vacuum Brazing 
  • Joint Designs 
  • Fixtures 
  • Metal Preparation 
  • Corrosion Resistance 
  • Removal of Chloride Fluxes 
  • Soldering 
  • Solderability 
  • Solders 
  • Fluxes 
  • Soldering with an Iron 
  • Torch Soldering 
  • Abrasion Soldering 
  • Ultrasonic Soldering 
  • Furnace Soldering 
  • Dip Soldering 
  • Resistance Soldering 
  • Joint Strengths 
  • Corrosion Resistance 
  • Conclusion 

Chapter 8—Codes and Standards for Welding Aluminum 

8.1 Codes and Standards for Welding Aluminum 

8.2 The Structural Welding Code for Aluminum 

8.3 What is the AWS A5.10, Specification for Bare Aluminum and Aluminum-Alloy Welding Electrodes and Rods? 

8.4 Is there a specification available specificallly for Friction Stir Welding? 

Annex A—References and Sources for Further Information 

The Most Interesting Figures from This Super Book


Figure 3.2—The Welding Heat Affect on a Heat-Treatable Alloy

Figure 3.4—The Natural Aging of 6061 Over Varying
Periods of Time and at Varying Temperatures

Figure 3.7—Solution Heat Treatment Requires that the Material be
Heated to Around 990°F [532°C], Followed by Quenching in Water

Figure 3.11—Shows the HAZ on Both
the Heat-Treatable and Nonheat-Treatable Alloys

Figure 6.27—Illustration of the Resistance Spot Welding Process

Figure 7.1—Schematic Representation of GTAW Equipment
Showing the Different Components
(Sometimes referred to as Tungsten Inert Gas (TIG) welding)

Figure 7.2—GTAW Welding Arc and Surrounding Components

Figure 7.10—Schematic Representation of the GMAW Process
(Sometimes referred to as MIG (Metal Inert Gas) welding)

Figure 7.11—GMAW Spray Transfer

Figure 7.14—The Characteristics of the Two Primary
Shielding Gases Used for GMAW Aluminum Welding