Aluminum Welding Automation

Alu­minum is the most dif­fi­cult alloy to weld. Alu­minum oxide melts at 3700oF, com­pared to alu­minum which melts at 1200oF. Because of this, alu­minum oxide should be thor­ough­ly cleaned from the sur­face before weld­ing. Alu­minum comes in heat-treat­able and non-heat treat­able alloys. Heat treat­able alu­minum alloys get their strength through a process called aging. Sig­nif­i­cant decrease in ten­sile strength can occur when weld­ing alu­minum due to over-aging. 

9 Groups of Major Alu­minum Alloy­ing Elements:

Fac­tors Affect­ing the Alu­minum Welding:

• Alu­minum Oxide Coating
• Ther­mal Conductivity
• Ther­mal Expan­sion Coefficient
• Melt­ing Characteristics

Wrought Alu­minum Alloys

1xxx Series

These grades of alu­minum are char­ac­ter­ized by excel­lent cor­ro­sion resis­tance, high ther­mal and elec­tri­cal con­duc­tiv­i­ties, low mechan­i­cal prop­er­ties, and excel­lent workability.

Mod­er­ate increas­es in strength may be obtained by strain hard­en­ing. The major impu­ri­ties are iron and silicon.

2xxx Series

These alloys require solu­tion heat treat­ment to obtain opti­mum prop­er­ties; in the solu­tion heat-treat­ed con­di­tion, mechan­i­cal prop­er­ties are sim­i­lar to, and some­times exceed, those of low-car­bon steel.

In some instances, pre­cip­i­ta­tion heat treat­ment (aging) is employed to fur­ther increase mechan­i­cal prop­er­ties. This treat­ment increas­es yield strength, with atten­dant loss in elon­ga­tion; its effect on ten­sile strength is not as great.

The alloys in the 2xxx series do not have as good cor­ro­sion resis­tance as most oth­er alu­minum alloys, and under cer­tain con­di­tions they may be sub­ject to inter­gran­u­lar corrosion.

Alloys in the 2xxx series are good when some strength at mod­er­ate tem­per­a­tures is desired. These alloys have lim­it­ed weld­abil­i­ty, but some alloys in this series have supe­ri­or machinability.

3xxx Series

These alloys gen­er­al­ly are non-heat treat­able but have about 20% more strength than 1xxx series alloys.

Because only a lim­it­ed per­cent­age of man­ganese (up to about 1.5%) can be effec­tive­ly added to alu­minum, man­ganese is used as a major ele­ment in only a few alloys.

4xxx Series

The major alloy­ing ele­ment in 4xxx series alloys is sil­i­con, which can be added in suf­fi­cient quan­ti­ties (up to 12%) to cause sub­stan­tial low­er­ing of the melt­ing range.

For this rea­son, alu­minum-sil­i­con alloys are used in weld­ing wire and as braz­ing alloys for join­ing alu­minum, where a low­er melt­ing range than that of the base met­al is required.

The alloys con­tain­ing appre­cia­ble amounts of sil­i­con become dark gray to char­coal when anod­ic oxide fin­ish­es are applied and hence are in demand for archi­tec­tur­al applications.

5xxx Series

The major alloy­ing ele­ment is Mag­ne­sium and when it is used as a major alloy­ing ele­ment or with man­ganese, the result is a mod­er­ate-to-high-strength work-hard­en­able alloy.

Mag­ne­sium is con­sid­er­ably more effec­tive than man­ganese as a hard­en­er, about 0.8% Mg being equal to 1.25% Mn, and it can be added in con­sid­er­ably high­er quantities.

Alloys in this series pos­sess rel­a­tive­ly good weld­ing char­ac­ter­is­tics and rel­a­tive­ly good resis­tance to cor­ro­sion in marine atmospheres.

How­ev­er, lim­i­ta­tions should be placed on the amount of cold work and the oper­at­ing tem­per­a­tures per­mis­si­ble for the high­er-mag­ne­sium alloys to avoid sus­cep­ti­bil­i­ty to stress-cor­ro­sion cracking.

6xxx Series

Alloys in the 6xxx series con­tain sil­i­con and mag­ne­sium approx­i­mate­ly in the pro­por­tions required for for­ma­tion of mag­ne­sium sili­cide (Mg2Si), thus mak­ing them heat-treatable.

Although not as strong as most 2xxx and 7xxx alloys, 6xxx series alloys have rel­a­tive­ly good forma­bil­i­ty, weld­abil­i­ty, machin­abil­i­ty, and rel­a­tive­ly good cor­ro­sion resis­tance, with medi­um strength.

Alloys in this heat-treat­able group are some­times formed in the T4 tem­per (solu­tion heat treat­ed but not pre­cip­i­ta­tion heat treat­ed) and strength­ened after form­ing to full T6 prop­er­ties by pre­cip­i­ta­tion heat treatment.

7xxx Series

Zinc, in amounts of 1 to 8% is the major alloy­ing ele­ment in 7xxx series alloys, and when cou­pled with a small­er per­cent­age of mag­ne­sium results in heat-treat­able alloys of mod­er­ate to high strength.

Usu­al­ly oth­er ele­ments, such as cop­per and chromi­um, are also added in small quantities.

Some 7xxx series alloys have been used in air­frame struc­tures, and oth­er high­ly stressed parts.

High­er strength 7xxx alloys exhib­it reduced resis­tance to stress cor­ro­sion crack­ing and are often uti­lized in an over­aged tem­per to pro­vide bet­ter com­bi­na­tions of strength, cor­ro­sion resis­tance, and frac­ture toughness.

Robots​.com car­ries a large vari­ety of weld­ing robots with dif­fer­ent work envelopes, foot­prints, mount­ing options and speeds. Please con­tact us today if you would like a quote on any of our weld­ing robots or to dis­cuss your needs and require­ments. You can also call us at 877−762−6881.