Characteristics- The Aluminium color is light gray to silver, but dull at oxidation but very bright once polished. This metal is very light in weight, soft, and with a minimum strength which can easily be cast, machined, forged, formed and welded. The low-temperature applications make the Aluminium suitable which can readily join by brazing, welding, and soldering. The lightweight of Aluminium in combination with strength makes it the second most popular metal that is welded. A break in Aluminum gives off no sparks and is not red in color prior to melting. It has good ductility at subzero temperature with light in weight and has high resistance to corrosion, high reflectivity to heat and light, good electrical and thermal conductivity. There is no color change to the aluminum once heated to weld or even brazing range.
Aluminum Welding Properties- The aluminum is joined with conventional machine and technology once used with other metals. Sometimes for special circumstances, the specialized technique may sometime be needed. The factors like appearance, cost, alloy, required strength, and joint configuration may be dictating choice in these industrial use with its advantages and limitations. The aluminum and aluminum alloy can be welded by a carbon arc, metal arc, and other arc processes. The aluminum in pure form can be alloyed with many other metals to produce a big range of aluminum physical and mechanical properties. The alloys are classified too into two categories, non-heat treatable and heat treatable. Aluminum alloy may be available as wrought alloy and cast alloy. The wrought alloy in the form of plate, tubing, sheet, plate, rolled shaped have same joining characteristics despite different shapes. The casting aluminum alloy in the form of sand, permanent mold and die casting have similar characteristics in welding. Thus cast and wrought metal have similar welding, brazing and soldering practices.
Applications & Challenges- The manufacturing process with aluminum helps to increase the life span of the spare parts. reduce its weight, and improve the integrity in cold temperature thus making the process suitable for the cryogenic piping, boat components, truck and trailer manufacturing, etc. The controlling of the heat input to deal with oxide layer Gas Tungsten Arc Welding (GTAW) is the process of choice due to its strength o joint and better aesthetic looks in the process of welding. The challenge best can be overcome by practice, practice and practice only. As high-quality music instrument can not make you a great musician, without practice welder can not be a great welder unless hone his skill by continuous practice
Technique and Power Source Selection- The common technique involved with aluminum are GTAW, gas tungsten arc welding and GMAW, gas metal arc welding. The selection of the process depends upon the available equipment, speed of manufacturing, aesthetic need, and strength of the weld required. The best result can be obtained by selection of the welding machine, prepare the base metal, proper technique application, visual inspection of the metal surface for dirt, dust, oil, and layer of oxide. The most trained steel welder may ace challenge to weld the aluminum due to high thermal conductivity and a very low melting point of alloy lead on to burn through if the welder is not an experienced one. In the GMAW the process is a challenge as the aluminum wire is softer than steel and may tangle with the drive roll. The pulsed GMAW helps with better control heat input, allow the welder to weld thin metal and the position of the welding is eased out.
Shielding Gas- The 100% argon is the gas of the choice as it has its penetration profile and good cleaning action as well. The alloy may need a mixture of shielding gas combining argon with helium with 75% helium which minimizes the magnesium oxide formation. In the GMAW for aluminum, argon is the choice while in steel the CO2 is the choice of gases. There may not be any special equipment required for argon in aluminum welding, as all the existing regulators and gas hoses may be used.