How To TIG Weld Aluminum


ADAPTED FROM NEW LESSONS IN ARC WELDING, THE LINCOLN ELECTRIC COMPANY, 1990

Though many metals are TIG welded, the steel most often related to the method is aluminum, particularly with metals of a smaller thickness. Some other processes, in fact, can be a part of aluminum, however within the lighter gauges probably the most acceptable course of is TIG. The recognition of aluminum in automotive functions has introduced TIG welding to a brand new golden age. Mechanically robust and visually interesting, TIG Welding is the primary course of chosen by skilled welders for skilled racing groups, and the avid auto fanatic or hobbyist.

The method is well-suited for aluminum, however there are a number of character problems with the steel that convey up factors that have to be thought-about if this materials is to be welded with constant ease and high quality.

THE CONFUSING THING ABOUT ALUMINUM

The pure steel has a melting level lower than 1200°F and doesn’t exhibit the colour adjustments earlier than melting so attribute of most metals. Because of this, aluminum doesn’t inform you when it’s scorching or able to soften. The oxide or “pores and skin” that kinds so quickly on its floor has a melting level nearly 3 times as excessive (3200°+F). So as to add to this confusion, aluminum even boils at a decrease temperature (2880°F) than this oxide melts. The oxide can also be heavier than aluminum and, when melted, tends to sink or be trapped within the molten aluminum. For these causes, it’s simple to see why as a lot as potential of this oxide “pores and skin” have to be eliminated earlier than welding. Fortunately, the reverse polarity half of the AC arc does an excellent job of clearing off portions of this oxide forward of the weld!

THAT ALUMINUM IS HOT!

Aluminum is a wonderful conductor of warmth. It requires a considerable amount of warmth when welding is begun, since a lot warmth is misplaced in heating the encircling base steel. After welding has progressed some time, a lot of this warmth has moved forward of the arc and pre-heated the bottom steel to a temperature requiring much less welding present than the unique chilly plate. If the weld is sustained farther on to the top of the 2 plates the place there may be nowhere for this pre-heat to go, it may well pile as much as such a level as to make welding tough until the present is decreased. This explains why a foot or hand Amptrol™ (present management) is really helpful together with your Sq. Wave TIG 175 or Sq. Wave TIG 275 – it allows you to simply change the present whereas concurrently welding.

Some aluminum alloys exhibit “scorching brief” tendencies and are crack-sensitive. Which means that on the vary of temperatures the place the liquid alloy is slushy (half stable and half liquid) or simply turned stable, it has not fairly sufficient tensile energy to withstand the shrinkage stresses which are occurring from cooling and transformation. The correct selection of filler steel and welding procedures, together with smaller beads, may help remove many issues of this type. Some consultants advocate backstepping the primary inch or so of every aluminum weld earlier than ending within the regular path.

FILLING THE GAP

The steel produced within the weld pool is a mix of metals that will need to have the energy, ductility, freedom from cracking, and the corrosion resistance required by the appliance. Appropriate selection of filler alloys minimizes the presence of intermetallic compounds and brittleness in aluminum fusion welds. See desk under for really helpful filler metals for varied aluminum alloys. 

Most charge of deposition is obtained with filler wire or rod of the most important sensible diameter whereas welding on the most sensible welding present. The wire diameter greatest suited to a particular utility relies upon upon the present that can be utilized to make the weld. In flip, the present is ruled by the obtainable energy provide, joint design, alloy sort and thickness, and the welding place.

RECOMMENDED FILLER METALS FOR VARIOUS ALUMINUM ALLOYS
Base Steel Beneficial Filler Metal¹
For Most
As-Welded Power
For Most
Elongation
EC
1100
1100
1100, 4043
EC 1260
1100, 4043
2219
3003
3004
5005
2319
5183, 5356
5554, 5356
5183, 4043, 5356
(2)
1100, 4043
5183, 4043
5183, 4043
5051
5052
5083
5086
5356
5356, 5183
5183, 5356
5183, 5356
5183, 4043
5183, 4043, 5356
5183, 5356
5183, 5356
5050
5052
5083
5086
5356, 5183
5554, 5356
5356, 5554
5556
5183, 5356, 5654
5356
5554, 5356
5183, 5356
6061
6063
7005
7039
4043, 5183
4043, 5183
5039
5039
5356³
5356³
5183, 5356
5183, 5356
Notes:Suggestions are for plate of “0” mood.Ductility of weldments of those base metals is just not appreciably affected by filler steel.
Elongation of those base metals is usually decrease than that of different alloys listed.For welded joints in 6061 and 6063 requiring most electrical conductivity, use 4043
filler steel. Nevertheless, if each energy and conductivity are required, use 5356 filler
steel and improve the weld reinforcement to compensate for the decrease conductivity of
5356.

A QUALITY DEPOSIT

Good weld high quality is obtained provided that the filler wire is clear and of top of the range. If the wire is just not clear, a considerable amount of contaminant could also be launched into the weld pool, due to the comparatively giant floor space of the filler wire with respect to the quantity of weld steel being deposited.

Contaminants on the filler wire are most frequently an oil or a hydrated oxide. The warmth of the welding releases the hydrogen from these sources, inflicting porosity within the weld. Lincoln Electric’s aluminum welding wire is manufactured beneath rigorous management to exacting requirements and is packaged to stop contamination throughout storage. Since filler wire is alloyed, or diluted, with the bottom steel within the weld pool, the compositions of each the filler wire and the bottom steel have an effect on the standard of the weld.

THE THREE CS: CLEAN, CLEAN AND CLEAN!

Items to be welded are normally shaped, sheared, sawed, or machined previous to the welding operation. Full elimination of all lubricants from these operations is a prerequisite for high-quality welds. Explicit care have to be taken to take away all oil, different hydrocarbons, and free particles from sawed or seared edges previous to welding. Sheared edges must be clear and easy – not ragged. For ease of cleansing, lubricants utilized in fabrication must be promptly eliminated.

To cut back the potential of porosity and dross in welds, cleanliness of the welding surfaces can’t be overemphasized. Hydrogen may cause porosity, and oxygen may cause dross in welds. Oxides, greases, and oil movies comprise oxygen and hydrogen that, if left on the sides to be welded, will trigger unsound welds with poor mechanical and electrical properties. Cleansing must be carried out simply previous to welding. A abstract of common cleansing procedures is given within the desk under.

COMMON METHODS FOR CLEANING ALUMINUM SURFACES
FOR WELDING
Sort of Cleansing
Compounds
Eliminated
 
Welding Surfaces Solely Full Piece
Oil, grease,
moisture, and
mud. (Use any
technique listed.)
Wipe with delicate alkaline answer.Wipe with hydrocarbon solvent,
similar to acetone or alcohol.Wipe with proprietary solvents.Dip edges, utilizing any of above.
Vapor degrease.Spray degrease.Steam degrease.Immerse in alkaline solvent.Immerse in proprietary solvents.
Oxides
(Use any technique
listed.)
Dip edge in robust alkaline
answer, then water, then
nitric acid. End with water rinse.Wipe with proprietary deoxidizers.Take away mechanically, similar to by
wire-brushing, submitting, or
grinding. For essential functions,
scrape all joints and
adjoining surfaces instantly
previous to welding.
Immerse in robust alkaline
answer, then water, then
nitric acid. End with water rinse.Immerse in proprietary options.



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