Think of a weld as having two zones: the weld bead, which is composed of mixed filler and base metal, and the base metal on either side of the weld, also called the heat-affected zone. Each zone is influenced by different factors, such as welding heat, distance of heat from the weld, size, thickness, and solidification rate, which will all ultimately influence the quality and mechanical properties of the weld.
Unless the base metal is in the annealed (“O” temper) or as-cast condition, fusion welding will decrease the strength of heat treatable aluminum alloys (series 2xxx, 6xxx, 7xxx) and non-heat treatable alloys (series 1xxx, 3xxx, 4xxx, 5xxx).
Welds in non-heat treatable alloys – These welds have excellent ductility. However, these alloys are hardened by cold working, which causes physical changes in the metal. The more it’s cold-worked, the stronger it gets. Welding it, however, takes the metal around the weld back to its annealed condition and softens it. Consequently, the only way to make the weld as strong as the parent material is to start with 0-tempered aluminum.
In heat-treated aluminum alloys, the last treatment heats the metal to about 400°F. However, welding makes the metal around the weld much hotter and may cause it to lose some of its mechanical properties and weaken it by as much as 30% to 40%. Post-weld heat treatments can improve the properties of heat-treatable aluminum alloys.
For gas welding, only 1100, 1188 and 4043 welding rods are ordinarily used. However, there are certain service conditions, such as immersion in fresh or salt water, exposure to certain chemicals or a sustained high temperature (over 150°F), that may limit the choice of welding rod alloys.
Hydro’s Welding Capabilities
Hydro’s welding capabilities include MIG Welding, TIG and Robotic TIG Welding, and Friction Stir Welding.
MIG Welding:
Used for material thickness above 1 mm; thickness less than 1mm can be welded using a pulsed MIG arc. Filler metal is added in the form of a wire fed through the welding torch.
MIG welding can be performed in any position and for all joint types.
TIG Welding is suitable for material thickness under 1mm; edge preparation could be necessary at an upper limit of about 10 mm.
Filler metal is normally used and introduced from the side.
TIG welding can be performed in any position and gives the most fault-free welds and excellent cosmetic appearance.
The welding speed is relatively high, even higher in Robotic TIG welding.
Robotic TIG Welding:
Popular for projects that require a precise, aesthetically perfect weld.
This method noticeably increases productivity. The position of the work piece is easy to control, facilitating welding from the optimum position to provide excellent results.
Friction Stir Welding:
A simple process that delivers completely void-free, impermeable joints of a higher strength than fusion welded joints.
- No filler metals or shielding gases are used.
- Heat has a minimal influence with only small heat stress in the material and flat surfaces.
- Process has few variables and these are easily controlled; the result is tight tolerances and stronger joints.
Aluminum extrusion transforms aluminum alloy into an extraordinary variety of products for consumer and industrial markets.
Hydro Extrusion is part of the world’s largest aluminum profile company, the North American leader in common alloy standard and custom extruded aluminum products, and the only soft alloy extruder in North America with indirect press technology.
Most of our extrusions undergo a variety of fabrication and/or finishing processes to transform them into usable components, including cutting, punching, machining, bending or welding. Find out more about aluminum welding rods, extruded profiles, solution heat-treatment, and the rest of Hydro’s unparalleled aluminum solutions.