AWS WHB-5.9 PDF

INTRODUCTION

Aluminum (Al), one of the most plentiful elements mined from the earth, is found in its oxidized form in bauxite, which, when refined, yields 40% to 60% alumina (aluminum oxide, Al₂O₃). The aluminum is separated from the oxygen using the Hall-Héroult electrolysis process, which was invented in 1886. This process made possible the production of aluminum on an industrial scale, increasing availability and drastically reducing the cost from the prevalent price of $600/lb in the years before. Aluminum usage in the world has grown exponentially since then, driven by the development of new joining technology and new applications.

Aluminum is highly ranked among the most useful metals known to manufacturers and fabricators. The strength of some aluminum alloys exceeds that of mild steel; aluminum can be cast, rolled, stamped, drawn, spun, stretched, or roll-formed. It can be hammered, forged, or machined with ease and speed, or extruded into a wide variety of shapes; then it can be given an equally wide variety of mechanical, electromechanical, chemical, or paint finishes.

Aluminum retains good ductility at subzero temperatures, is highly resistant to corrosion, and is not toxic. It has good electrical and thermal conductivity, is highly reflective of heat and light, and is nonsparking and nonmagnetic.

The properties of aluminum and aluminum alloys are valuable for critical applications in the space and aircraft, marine, and automotive industries; for structural applications; for vessels and storage tanks; and are also vital for countless consumer products. Processes to weld aluminum continue to improve and have contributed to the widespread use of this remarkable material.

Most of the common joining methods—welding, brazing, soldering, adhesive bonding, and mechanical fastening—can be used to join aluminum.¹ All processes, except mechanical fastening, are discussed in this chapter; a brief section on aluminum cutting is also included.^{2, 3}

1. For information on welding, brazing, soldering, and adhesive bonding processes, refer to American Welding Society (AWS) Welding Handbook Committee, 2004, Welding Handbook, 9th ed., ed. A. O'Brien, and Welding Processes, vol. 2, Part 1, ed. A. O'Brien, and Welding Processes, vol. 3, Part 2, 2007, ed. A. O'Brien and C. Guzman, Miami: American Welding Society. Refer to Appendix B of this volume for a list of chapter contents for the five volumes of Welding Handbook, 9th ed.

2. At the time this chapter was prepared, the referenced codes and other standards were valid. If a code or other standard is cited without a date of publication, it is understood that the latest edition of the document referred to applies. If a code or other standard is cited with the date of publication, the citation refers to that edition only, and it is understood that any future revisions or amendments to the code are not included; however, as codes and standards undergo frequent revision, the reader must consult the most recent edition.

3. Welding terms and definitions used throughout this chapter are from American Welding Society (AWS) Committee on Definitions and Symbols, 2010, Standard Welding Terms and Definitions, AWS A3.0M/A3.0:2010, Miami: American Welding Society.