TIP TIG Welding is always better quality than TIG and 100 to 500% faster with superior quality than TIG - MIG - FCAW.

 

Panasonic weld equipment issues
and lack of aluminum welding process expertise:

 

The company I visited welds 6xxx series, extruded aluminum, thin gage parts. They had purchased a Panasonic VR OOGAL 11robot, with a Panasonic 350 amp Panastar RA 350 pulsed power source. For the welds they used an 0.046, 4043 wire and argon. The MIG wire spool was mounted on top of the robot, and they used a regular four-drive roll feeder with a water-cooled gun.

The problem robot welds were short lengths, 5/8 to ¾ long. The robot welds are made on aluminum square tubes 0.070 thick. The 6xxx tubes are welded to a thicker alum part 3/16 thick. Since they purchased the robot the completed welds never look consistent over their short lengths. All the thin tube welds were made with the same weld data, yet in the same locations on the parts, some welds look fluid while other welds look cold.
Most of the welds ended up with a black and dirty appearance yet the push gun angle is correct. These welds caused so many issues the company was ready to give up the robot and go back to manual TIG. For the rest of the story, click here.

Aluminum Welding Tips and Information

Aluminum alloys can provide unique physical properties.

Weight. Aluminum is three times lighter than steel and yet aluminum can provide higher strength when alloyed with specific elements.

None Magnetic. Since aluminum is nonmagnetic, arc blow is not a problem during aluminum welding.

Thermal Conductivity. With a thermal conductivity rate that is five to six times higher than steel and the aluminum welds watch out for lack of weld fusion especially at the weld starts. With alum being more sluggish and less fluid, aluminum can be welded in all positions with spray and pulsed with relative ease. In contrast to steel the high conductivity of aluminum acts as a heat sink making weld fusion and weld penetration more difficult to achieve on parts > 4 mm.. However on thin parts, the rapid build up of heat in the alum parts can add to high weld fluidity and weld burn through potential.

 

 

 

Aluminum Porosity and Hydrogen. When MIG or TIG welding aluminum, the weld decision maker should always be aware that this is one of the metals most susceptible to porosity. Hydrogen dissolved in the liquid weld metal will try to escape as the aluminum solidifies and the trapped hydrogen will result in weld porosity which is often extensive. The main cause of porosity in aluminum welds is the absorption of hydrogen in the weld pool which forms gas pores in the solidifying weld metal. The most common sources of hydrogen are hydrocarbons and moisture from contaminants on the aluminum base metal and on the filler wire surface. Also water vapor from the MIG or TIG shielding gas will provide the same results.

Hydrogen cracking is common with carbon steels but hydrogen cracking will not occur with aluminum. Hot cracking or solidification cracking is a primary cause for aluminum cracks.

ALUMINUM Welds and Solidification Cracking.

Alum Solidification cracks can happen due to thermal expansion and contraction during the aluminum these factors generates high stresses sometimes tearing the weld apart..


Common causes of alum solidification cracks.

[a] incorrect choice of alum weld consumable.

[b] Concave welds, undersize welds, and welds with insufficient weld throat. (The weld throat depth must be sufficient to compensate for the weld contraction stresses).

[c] Weld joints too rigid.

[d] Poor weld weld geometry.

[e] Poor weld joint design. Weld restraint and weld stresses can be reduced by focussing on the weld edge prep, the weld sequence.

[f] Excess weld heat, watch weld pass sequence and on multi-pass welds consider interpass temperature control.

Solidification cracking is reduced with the selection of crack-resistant filler metal like the 4xxx and 5xxx filler metal. Be wary when choosing the filler metal to specifically reduce weld cracking, as the weld metal may provide lower strength than the parent metal and will not respond to heat treatment if applied.

ALUMINUM Liquation Cracking. In contrast to hot cracking which occurs in the weld, while MIG or TIG welding aluminum liquation cracking will occur in the heat affected zone (HAZ). With liquation cracking low melting point films are formed at the grain boundaries and these films (liquid elements)cannot withstand the contraction stresses during the weld metal solidification. Heat treatable alloys, like the 6xxx and 7xxx series are sensitive to liquation cracking. To reduce the potential for liquation cracking, consider a weld wire with a lower melt temperature than the parent metal. With alloy 6061 - 6082, liquation cracking can occur in the partially melted zone when a weld with good dilution is made with 5356 or similar filler metal is utilized. In contrast when welding the same alloys with 4043 liquation cracking should not occur.

 

 

All it takes is a little weld process knowledge
and you will not produce welds like this.

Aluminum Oxides. Aluminum will combine with oxygen to form an aluminum oxide layer. This layer will form instantly as the aluminum surface is ground or machined. The aluminum oxide layer while very thin can also be very porous. The oxide layer will readily trap moisture, oil, grease and other materials adding to the potential for hydrogen pickup. The aluminum oxide layer provides excellent corrosion resistance, however this layer must be removed before welding as it prevents fusion due to its higher melting point (3700 degrees F). The weld arc gas molecules, the fore hand (push) technique, mechanical cleaning, wire brushing, solvents and chemical etching and voltage control are used for the oxide removal. One of the best practices to attain clean alum MIG welds is to use the lowest possible voltage which assures a short arc length, and a concentrated plasma which is beneficial for the oxide removal.

Aluminum alloys that are difficult to weld.

Alloys that may be sensitive to hot cracking are found in the 2xxx series, alum-copper and in the 7xxx series alum-zinc.

With the 2xxx series hot cracking sensitivity increases with Cu < 3% and decreases with Cu > 4.5%. Avoid weld practices that promote high heat input as grain boundary segregation cracking potential.

7xxx alloys that contain Al-Zn-Mg like 7005 resist hot cracking and have better mechanical weld properties than Al-Zn-Mg-Cu alloys like 7075 that contain small amounts of Mg and Cu
which extend the coherance range increasing the crack sensitivity. Zirconium is added to refine grain size and reduce crack potential. Electrode 5356 is often recommended for this group as the magnesium helps prevent cracking. The 4043 electrode would provide excess Si promoting brittle Mg2Si particles in the welds.

Be careful when welding dissimilar alum alloys as extending the coherence range increases the crack sensitivity. When welding alloys that do have good weldability like welding a 5xxx alloy to a 2xxx base alloy or a 2xxx filler on a 5xxx alloy and vice a versa you can end up with high Mg and Cu and increase the coherence range increasing the crack sensitivity.


Five Common Aluminum,
MIG Filler Welding Metals:

5356 - 4043 - 1100 - 5556 - 4047

Usually the filler metal selected should be similar in composition to the base metal alloy for example a 1XXX filler wire for welding 1XXX - 3XXX-series base metal alloys. Special consideration is however required when weldability is an issue. Weldability of non-heat-treatable aluminum alloys should be measured in resistance to hot cracking and porosity potential. Hot cracking issues are encountered when welding with alloys sensitive to cracking, alloys subject to excess heat or parts that are highly constrained.

Cracking issues can occur when low strength weld alloys like 1XXX are used to join 5XXX alloys (or vice versa) or when welding dissimilar metals with different strengths. The best filler metals when hot cracking occurs is to use 4xxx fillers.

What's the best alum filler for "high temp or low temp service"?

Weld mechanical properties such as yield, tensile strength and elongation are affected by the choice of aluminum base and filler alloys.

With groove welds, the heat affected zone (HAZ) dictates the strength of the joint. The non-heat-treatable aluminum alloys HAZ will be annealed and their HAZ will be the weakest point.

Heat-treatable alloys require much longer periods at annealing temperatures combined with slow cooling to completely anneal them so that weld strength is less affected. When welding alum please remember that preheating, excess interpass temperatures and and excess weld heat from over sized welds, slow weld speeds and weaving all increase temperature and time at temperature all can influence the strength levels that will be attained.

In contrast to groove welds the fillet weld strength is dependent on the composition of the filler alloy used to weld the joint. For example the selection of 5XXX instead of 4XXX can provide twice the weld strength.

 

When to use either
4043 or 5356 filler wire?

 

4043 aluminum filler wire is an aluminum wire with 5% silicon. This wire was developed for welding the 6xxx series aluminum alloys. 4043 may also be used to weld the 3xxx series or 2xxx alloys. 4043 is also used for welding castings.


[] 4043 has a lower melting point and provides more weld fluidity than 5xxx series filler alloys. 4043 will provide cleaner "less black soot because it doesn't contain magnesium.

[] 4043 is often preferred by welders as it provides better weld wetting, smoother weld surface more stable transfer and is also less sensitive to weld cracking when welding the 6xxx series base alloys.

[] 4043 provides more weld penetration than 5356, however the 4043 will produce welds with less shear strength and ductility than those made using 5356.

[] 4043 is used for applications when the service temp above 150 F, in contrast 5356 is not suited to applications where prolonged heat is applied.

[] 4043 is not well suited for welding Al-Mg 5xxx alloys and should not be used with
5xxx alloys with > 2.5% Mg, alloys such as 5083, 5086 or 5456 as excess magnesium-silicide (Mg2Si) can develop in the weld structure decreasing ductility and increasing crack sensitivity. (One exception to this 4043 rule is when welding the 5052 alloy which has a low magnesium content.)

[] When shear strength is the concern consider 5xxx rather than 4xxx filler metals.

[] As welded 4043 will provide lower ductility than 5356, this is important if you are shaping the welded part after welding to remember this fact.

[] For MIG wire feedability note the 4043 or 1100 are softer than 5356 so expect more wire feed issues.

 

5356 wire is an aluminum wire with 5% magnesium. This is the most common aluminum filler wire due to superior strength, ductility and superior MIG wire feedability. 5356 was developed to weld the 5xxx structural alloys and also the 6xxx series extrusions. Do not use the 5356 on castings as they are high in silicon. 5356 is not suited to weld applications in which the service temperatures exceed 150 degrees Fahrenheit (65 degrees Celsius). The formation of Al2Mg at elevated temperatures at the grain boundaries makes the alloys prone to stress corrosion. For components that will be anodized after welding, 5356 is recommended for the best color match, in contrast 4043, will turn black when anodized.

 

Weld Strength and Weld Heat Considerations:

As mentioned, typically the resulting HAZ of a groove weld will determine the strength of the joint and usually a variety of filler alloys will match or exceed this strength requirement. However, there are many other factors for consideration when welding the heat treat or non-heat treatable alloys.

Heat treatable alloys require a specific time at temperature to fully reduce their strength. The strength reduction in the heat treatable alloy may be minimal or extensive during the welds, defendant on the weld procedures and technique and fixtures utilized. The amount of strength loss due to weld heat is influenced by both time / temperature. Faster weld speed or smaller welds produce less weld heat in the weld area. Fixtures that provide heat sinks lower the weld heat input. The lower the weld heat the higher the as welded strength.

The following can add unnecessary weld heat and require consideration on the influence of weld heat on aluminum alloys;

[1] lack of interpass weld temperature controls on, multi-pass welds.
[2] excess preheating,
[3] slow weld speeds,
[4] wide (8 mm) weld weaves,
[5] oversized welds,(>6 mm fillets),
[6] welding thin parts or many welds concentrated is a small area,
[7] unnecessary high weld current and voltage.


Shear or Tensile Strength. In contrast to aluminum groove welds, the fillet weld strength is mostly dependent on the composition of the alum filler alloy used. The fillet joint strength is based on shear strength which can be affected considerably by filler alloy selection.

When welding alum structural applications and considering the 5xxx series or 4xxx series filler metals, the tensile strength of groove welds differences may be minimal. However serious consideration is required when considering the shear strength of aluminum "fillet welds". The approx. transverse shear strength of 4043 is around 15 ksi while the shear strength of 5356 is approx. 26 ksi. The bottom line the 5356 provides superior ductility and shear strength.

WIRE TYPE AND FILLET WELD SIZE: Alcotec reports that tests have shown that a required shear strength value in a fillet weld in 6061 base alloy required a 1/4 inch (6 mm) fillet weld with 5556 filler compared to a 7/16. (11 mm) fillet with 4043 filler alloy to meet the same required shear strength. This can mean the difference between a one run fillet and a three run fillet to achieve the same strength.

Ductility and alum welds may be a consideration if forming is to be performed after welding or if the alum weld is going to be subjected to impact loading. Also ductility should be given consideration when bend tests are applied during weld procedure qualification.

In contrast to the 5xxx series, the 4xxx series filler alloys provide lower weld ductility, this is addressed with special requirements within the code or standards relating to the weld test sample thickness, bending radius, and material condition.

Corrosion Resistance: Most aluminum base alloy filler alloy combinations provide satisfactory protection for against general exposure to the atmosphere. One filler alloy developed for use within a specific corrosive environment, is the 5654 alloy. The 5654 alloy was developed to weld storage tanks that contain hydrogen peroxide. The difference in alloy performance can vary based upon the type of exposure. Filler alloy charts ratings are typically based on fresh and salt water only. Corrosion resistance can be a complex subject when looking at service in specialized high corrosive environments, and may necessitate consultation with engineers from within this specialized field. Good contact Alcotec.

Service Temperature: Stress corrosion cracking (SCR) is an undesirable condition which can result in premature failure of a welded component. One condition which can assist in the development of SCR is Magnesium segregation at the grain boundaries of the material. This condition can be developed in the Mg alloys of over 3 % through the exposure to elevated temperature. When considering service at temperatures above 150 Deg F, we must consider the use of filler alloys which can operate at these temperatures without any undesirable effects to the welded joint. Filler alloys 5356, 5183, 5654 and 5556 all contain in excess of 3 % Mg, typically around 5%. Therefore, they are not suitable for temperature service. Alloy 5554 has less than 3 % Mg and was developed for high temperature applications. Alloy 5554 is used for welding of 5454 base alloy which is also used for these high temp applications. The Al – Si (4xxx series) filler alloys may be used for some service temperature applications dependent on weld performance requirements. More info contact Alcotec.

Color Match After Anodizing: The color of an aluminum alloy when anodized depends on its composition. Silicon in aluminum causes a darkening of the alloy when chemically treated during the anodizing process. If 5% silicon alloy 4043 filler is used to weld a 6061 application, and the welded assembly is anodized, the weld becomes black and is very apparent. A similar weld in 6061 with 5356 filler does not discolor during anodizing, so a good color match is obtained.

Post Weld Heat Treatment: Typically, the common heat treatable base alloys, such as 6061-T6, lose a substantial proportion of their mechanical strength after welding. Alloy 6061-T6 has typically 45,000 PSI tensile strength prior to welding and typically 27,000 PSI in the as-welded condition. Consequently, on occasion its desirable to perform post weld heat treatment to return the mechanical strength to the manufactured component.

If post weld heat treatment is the option, it is necessary to evaluate the filler alloy used with regards to its ability to respond to the heat treatment. Most of the commonly used filler alloys will not respond to post weld heat treatment without substantial dilution with the heat treatable base alloy. This is not always easy to achieve and can be difficult to control consistently. For this reason, there are some special filler alloys which have been developed to provide a heat treatable filler alloy which guarantees that the weld will respond to the heat treatment.

Filler alloy 4643 was developed for welding the 6xxx series base alloys and developing high mechanical properties in the post weld heat-treated condition. This filler alloy was developed by taking the well-known alloy 4043 and reducing the silicon and adding .10 to .30 % magnesium. This chemistry introduces Mg2Si into the weld metal and provides a weld that will respond to heat treatment.

Filler alloy 5180 was developed for welding the 7xxx series base alloys. It falls within the Al-Zn-Mg alloy family and responds to post weld thermal treatments. It provides very high weld mechanical properties in the post weld heat-treated condition. This alloy is used to weld 7005 bicycle frames and will respond to heat treatment without dilution of the thin walled tubing used for this high performance application. Other heat treatable filler alloys have been developed including 2319, 4009, 4010, 4145, 206.0, A356.0, A357.0, C355.0 and 357.0 for the welding of heat treatable wrought and cast aluminum alloys.

Work Hardening is used to produce strain-hardened tempers in none-heat treatable alum alloys. (Increases strength). This is influenced by mechanical energy leading to deformation. As the deformation occurs the alum alloy becomes stronger, harder and less ductile.

Precipitation Hardening (artificial aging). Precipitation heat treat precedes solution heat treat. Hold alloys at a specific temp long enough to allow constituents to enter into solid solution, then cool rapidly to hold constituents to remain in solid solution Artificial aging follows.The alloy is reheated to a lower temp and holding for a specific time. This heat treat produces superior mechanical properties. Please note on the heat treatable alloys that have undergone this treatment, the weld metal heat will change the mechanical properties in both the HAZ and base metal.

Aluminum Filler Metal Information:
Aluminum Filler	International Specs	Chemistry	Melt Temp	Yield	Tensile
Electrode 1050A	ISO / Germany A199.5 France A5 Italy P-AP5
Electrode 1100	ESAB OK 18.01 Conarcao A400S Pacweld 421 AA	Al 99% - Mn0.05 Cu 0.05 - 0.2 Si - Fe0.95 Zn 0.10	1190 to 1215F 643 to 657C	5 ksi 34MPA	13 ksi 90 MPa
Electrode 1100 - H12				15 ksi	16 ksi
Electrode 1100 - H14				17 ksi	18 ksi
ER filler 1100 used to weld all 1XXX alloys plus 3003 and 5005 alloys
Electrode 1188	UNS A91188	Al 99.8% Si 0,06, Fe 0.06 Cu 0.005, Mn 0.01, Zn 0.03. Ti0.01	1215F 657C
Electrode 2319	UNS A 92319 used for Al lithium aircraft alloy 2090 2319 is heat treatable good strength ductility on Al Cu Casts don't use 2319 on 5XXX	Cu 5.8 - 6.8 Si 0.2 / Fe0.3 Mn0.2-0.4 Mg 0.02 Zn 0.1 Ti 0.1 - 0.2	1010 to 1190F 543 to 643C		2319 used on 2219 2014 plus alum copper cast alloys Dont use on 5XXX
ER4XXX ALUMINUM ELECTRODES. ER 4043 - 4047 Moderate strength good corrosion resistance. (Less strength than 5356) ER 4043 - 4047 Low sensitivity to cracking while welding ER 4043 - 4047 Lower weld ductility than 1XXX - 2XXX - 5XXX ER 4043 - 4047 Can weld 1XXX - 3XXX - 6XXX 2014 / 2219 / 005 /5052 / 7005 / 7039 Al - Si and Al - Si - Mg casts
Electrode 4043	Germany ISO S - ALSi5 Italy S-AlSi5 France A- S5 "don't" use to weld high Mg 5XXX 5083 - 5086- 5456 ESAB 0K18.04 Packweld 425/AA Thysen UnAlSi5 Century 331 400 Conarco A408	Si 4.5 - 6 Fe 0.8, Cu 0.3 Mn 0.05 Mg 0,05, Zn 0.1 Ti 0.2	1155F 623 C	10 ksi 69 Mpa	Moderate strength good corrosion resistance Low sensitivity to cracks while welding Lower ductility than 1XXX 2XXX 5XXX 21 ksi 145 Mpa Can use on 1XXX 3XXX 6XXX 2014 2219 5005 5052 7005 7039 Al-SI + Al Si Mg casts
Electrode 4043 - 18				39 ksi 270 MPa	41 ksi 285 MPa On thin alum sheet 4047 is used as an alternative to 4043
Electrode 4047	Germany ISO S- AlSi12 Italy S-AlSi12 France A-S12	Si 11 - 13 Fe 0.8, Cu 0.3 Mn 0.15, Mg 0.1 Zn 0.2	1050F 565C		Moderate strength good corrosion resistance Low sensitivity to cracks while welding Lower ductility than 1XXX 2XXX 5XXX Can use on 1XXX 3XXX 6XXX 2014 2219 5005 5052 7005 7039 Al-SI + Al Si Mg casts. Faster feeeze than 4043 can prevent formation of crater cracks
Electrode 4145		Si 9.3 - 10.7 Fe 0.8 Cu 3.3 -4.7 Mg/Mn/Cr 0.15 Zn 0.2	970F		Low sensitivity to weld cracks on 2XXX Good for Al - Cu Al -Si- Cu cast alloys responds to heat treat can repalce 4043 4047 will result in lower ductility
ER 4145 Low sensitivity to weld cracking on 2XXX alloys ER 4145 Good for Al - Cu Al Si Cu Cast Alloys. Responds to heat treat. ER 4145 Can replace ER 4043 4047, will however have lower ductility.
Electrode 4643		Si 3.6 - 4.6 Fe 0.8, Cu 1.1 Mg 0.1 - 0.3 Zn 0.1, Mn 0.05 Ti 0.15	1065 to 1175F 573 to 635C		4043 is a goodchoice for the welding of heat-treatable alloys especially the 6XXX series. 4043 has a lower melting point and more fluidity than the 5XXX series filler alloys. 4043 has good welability. 4043 wires are also less sensitive to weld cracking with the 6XXX series base alloys. 4043 is suitable for sustained elevated temperature service, above 150 deg F (65 deg C).
KEEP THE ALUM CLEAN BEFORE WELDING. Aluminum has a great affinity for hydrogen, which can be picked up from many sources, dirt, paint, moisture, markers, lubricants, etc. All mentioned can form hydrocarbons causing serious porosity which can weaken the weld. WELD POROSITY IS MORE OF A CONCERN WITH ALUMINUM THAN IT IS WITH STAINLESS OR STEEL. THE REASON STAINLESS AND CARBON STEEL TYPICALLY HAVE MUCH GREATER YIELD STRENGTH. To clean aluminum, consider degreasing solvents and clean stainless steel brushes. Caution some grinding wheels will contaminate aluminum, (use wheels recommended for alum). Also on heat treatable alloys, plasma gouging and cutting can cause micro cracks on component edges, (remove edges with grinder)
ER5XXX ELECTRODES: ER 5XXX Higher strength than other aluminum electrodes ER 5XXX used to weld 5XXX - 6XXX - 7005 alloys Don't use ER5XXX filler on 2XXX alloys ER 5XXX Higher Mg Higher strength and crack sensitivity decreases ER 5XXX Pre heat and interpass max temp 150F 65C
Electrode 5056	ISO/Germany AlMg5 France A-G5MC Italy P-AG5
Electrode 5083	ISO /Germany AlMg4.5Mn France A-G4,5MC
Electrode 5154	ISO AlMg3.5 Germany AlMg3 France A-G3C
Electrode 5183	Germany S-AlMg4.5Mn France AlMg4.5Mn	Mg 4.3 - 5.2 Si/Fe 0.4 Cu 0.1 Mn 0.5 -1 Cr 0.05 -0.25 Zn 0.25 Ti 0.15	1075 to 1180F 579 TO 637 C		Dont use on high temp applications 5183 is for welding high magnesium alloys to meet higher tensile strength requirements than 5356. Use on 5083 and 5654 base materials when required tensile strengths are >40,000 psi (276 MPa) or greater. Typical applications are in the marine and cryogenic industries, and high strength structural aluminum fabrication.
REDUCE THE ALUMINUM "BLACK OXIDES" The black soot that frequently occurs with MIG aluminum welds, is a combination of aluminum and magnesium alloys that combine with oxygen and form oxides that appear black. The oxides that form have a lower boiling point than the arc temperature, they evaporate and condense on the weld or HAZ area. Expect more soot from higher magnesium alloys. For example the common 5356 filler metal can provide more soot than E4043 filler metal. Excess soot is usually an indication of weld porosity issues. The soot can caused and corrected by the following. [A] INSUFFICIENT WELD ENERGY. TO ASSIST IN THE REMOVAL OF THE ALUM SURFACE OXIDES. INCREASE WELD CURRENT / WIRE FEED OR DECREASE WIRE SIZE FOR MORE CURRENT DENSITY. [B] ARC LENGTH THAT IS TOO LONG. INSUFFICIENT PLASMA ARC ENERGY CONCENTRATION FOR THE SURFACE OXIDE REDUCTION. REDUCE THE ARC LENGTH BY LOWERING WELD VOLTS. [C] INCORRECT WELD GUN ANGLE. ENSURE THE FOREHAND (PUSH) TECHNIQUE IS USED TO DIRECT THE ARC TO BREAK UP THE ALUM OXIDE SKIN IN FRONT OF THE WELD. BACK HAND (PULL) WILL PROVIDE THE WORST RESULTS. [D] INSUFFICIENT GAS COVERAGE. USE 40 TO 60 CUFT/HR AND ENSURE THE GAS CUP IS A LITTLE WIDER THAN THE WELD AND HEAT AFFECTED ZONE WIDTH. IF USING HELIUM ENSURE HELIUM FLOW METER IS USED AND ENSURE HELIUM FLOW RATE IS A MINIMUM OF 45 CUFT/HR [E] WELD SPEED TO FAST. MAY NOT ALLOW ADEQUATE BREAKUP OR REMOVAL OF ALUMINUM SURFACE OXIDES. [F] ALUM SURFACE CONTAMINATED. NEEDS CLEANING. [G] CYLINDER GAS CONTAMINATED, TYPICALLY DUE TO POOR DISTRIBUTOR GAS FILLING PRACTICE WHICH LEAVES EITHER CO2, OXYGEN OR MOISTURE IN THE CYLINDERS.
Electrode 5356	Germany France S - AlMg5 Italy S-ALMG5 ESAB OK 18.15 Pacweld 430A Conarco A404 Thyssen UnAlMg5	Mg 4.5 - 5.5 Cu 0.1 Ti 0.06 - 0.2 Cr/Mn 0.05-0.2 Zn 0.1 Si 0.25 / Fe 0.4	1180F 637C		Dont use on high temp applications. 5356 is a great general purpose filler alloy designed for the welding of 5XXX series alloys when <40,000 psi (276 MPa) tensile strength is required. 5183 and 5556 sometimes used as an alternative to 5356
Electrode 5454	ISO AlMg3Mn Germany AlMg2.7Mn France A-G2.5MC
Electrode 5554	Italy S-AlMg3Mn	Cu 0.1, Mn0.05-1 Mg 2.4 - 3 Cr/Ti 0.05-0.2 Zn 0.25	1115 to 1195F 601 to 646C
Electrode 5556	ISO - AlMg5.2MnCr Germany AlMg5 ESAB OK 18.6 Pacweld 431 AA Conarco A4045	Mg 4.7 - 5,5 Si 0.25, Fe0.4 Cu 0.1, Mn 0.5 - 1 Cr 0.05 -0.2 Zn 0.25 Ti 0.05 -0.2	1180F 637C		5556 weld deposits will provide matching tensile strengths for the 5XXX alloys, such as 5083 and 5654. Contains increased amounts of magnesium and manganese. Dont use on high temp applications
Electrode 5654		Mg 3.1 - 3.9 Cu 0.05, Mn0.01 Cr 0.15-0.35 Ti 0.05 -0.15 Zn 0.02			dont use on high temp applications

ALUMINUM WELD TIPS AND DATA:

THIS ALUMINUM MIG WIRES A BARGAIN.

If you get your aluminum MIG wire at a bargain price, its likely you will have weld consequences. To test an aluminum MIG wire, take two 1/4 alum plates, six inches long. Start a 3/16, horizontal fillet weld approx. one inch from the end of the plate. Make the weld is four inches long. Don't weave use fore hand. After the weld has cooled, put welded plate in vice and use hammer to fold the plates in on the weld.

In contrast to steel welds, a good, alum weld with proper side wall fusion should break in most cases in the weld metal. Examine the broken weld surface for porosity. Clean looking, small pore porosity is found in the best of aluminum welds. Blackish looking small porosity often results from lubricants from the material surface. Small gray, oxidized weld porosity often results from air trapped in the joint or oxygen from the gas cylinders or lines. Extensive shiny porosity may be an indication of moisture pickup. Ensure synthetic impermeable hoses are used for your aluminum MIG gas delivery rather than neoprene or rubber hoses.

Weld porosity can be blamed on many materials that can contaminate both the weld wires and base metals. With aluminum, hydrogen is the prime cause. The bottom line keep the plates clean and at the ambient shop temperature. If necessary for your application grind the weld edges. Provide a protective cover for the alum weld wires. When the weld wires are not in use store in clean dry area. Good manufacturers of aluminum MIG wires will use extensive manufacturing controls to ensure you have a clean consistent MIG wire. There is a price to be paid for this weld wire quality. Compare your bargain priced aluminum wire with a quality and consistent product from a company like Alcotec.

 

Aluminum, Oxidation, Hydrogen and Porosity.
Aluminum has a high maximum solubility for hydrogen atoms in the liquid form and a low solubility at the solidification point.

Hydrogen dissolved in the liquid weld metal will try to rise out of the weld during the aluminum solidification. Some hydrogen gas pores will be trapped and porosity will occur.

Aluminum combines with oxygen to form an aluminum oxide layer. This micro surface layer will form instantaneously if the oxide is removed by machining or grinding. The oxide layer is porous and can easily trap moisture, oil, grease and other materials. The aluminum oxide layer provides excellent corrosion resistance, but must be removed before welding as it prevents fusion due to its much high melting point point than the aluminum alloy .

Arc polarity, plasma molecular action, mechanical cleaning, solvents and chemical etching are all used to attack the oxide layer. When MIG welding if the layer is not removed sufficiently a black soot will appear either side of the weld. To eliminate the soot, first try to lower the arc length (voltage) as this makes the MIG plasma more dense which provides a more concentrated plasma cleaning action.

The majority of aluminum weld porosity results from entrapped hydrogen gas in the weld pool. Hydrogen is highly soluble in molten aluminum. Hydrogen can be derived from many sources.

[a] Hydrogen from base metal contaminates, hydrocarbons, lubricant, oils dirt, grease, moisture, paints and compressed air and contaminates from pneumatic cleaning tools or cleaning brushes.

[b] Hydrogen from lubricant contaminates on the alum weld wire surface.

[c] Hydrogen from moisture, water leaks in water cooled torches. Water from the gas cylinders. Water from the porous, hydrated, alum oxide layer on the base metal surface.

[d] Hydrogen that results from high humidity, condensation on parts and weld wires.

[e] Hydrogen that results from contaminates from grinding wheels.

To minimize hydrogen and weld porosity potential consider, cleaning, degreasing, stainless wire brushes or carbide wheels to remove the oxide surface. Remember you can always find porosity in the alum weld, the real question is how much is acceptable and what inspection and weld process control method will be used to control the porosity.

To reduce aluminum weld porosity potential, slow down the weld solidification rate to allow the hydrogen to exit. Reduce alum weld porosity with the following 11 points.

[1] To remove the alum surface oxide consider a die grinder (>30,000-rpm) rotary, coarse carbide file. An effective cleaning solution is acetone, beware highly flammable..

[2] Increasing weld parameters, with MIG increase the wire feed rate.

[3] Increase weld size.

[4] Avoid weaves.

[5] Slow down weld travel speed.

[6] Use smaller diameter MIG wires.

[7] Evaluate the weld procedure so that weld heat and weld sequence is used as a tool for porosity reduction.

[8] Use lowest possible MIG weld voltage. Low weld voltage results in short arc lengths which create more energy in the arc plasma providing improved arc cleaning action of the surface alum oxides.

[9]Use a higher energy gas mix like 60 helium - 40 argon. The helium requires higher weld voltage. The 60 helium mix is superior to the common 75 helium 25 argon mix, as the the higher argon content helps stabilize the arc and provides superior weld cleaning action.

[10] Don't use MIG wire wipes clipped on the wire.

[11] Don't use anti spatter within 2 inches of the weld. If you know how to set a weld you would not use anti-spatter.

If you are teaching your self, or providing weld process control training for others, the following resources are the key to attaining MIG and flux cored weld process optimization. Item.1. The Book: "A Management & Engineers Guide To MIG Weld Quality, Productivity & Costs" Item 2. A unique robot MIG training or self teaching resource. "Optimum Robot MIG Welds from Weld Process Controls". Item 3. A unique MIG training or self teaching resource. " Manual MIG Weld Process Optimization from Weld Process Controls". Item. 4. A unique flux cored training or self teaching resource. "Optimum Manual and Automated Flux Cored Plate and Pipe welds. Item 5a."Proceso de Soldadura MIG Manual" (MIG Made Simple. Self teaching in Spanish) Item 6a. The Self Teaching MIG Book/ Video. (MIG Made Simple in English). Note: Items 2-3-4 are the most comprehensive process control, self teaching and training programs ever developed.. Visit Ed's MIG / flux cored process control books and CD training resources.

Continue Aluminum Welding Section 2.