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Section 5
Shielding Gas Selection for Steels
The choice of gas depends on two factors, weld penetration and appearance. Pure argon provides the best looking
welds, but has the least weld penetration. To increase penetration C02 is added to the mix. C02 percentages range from
10% to 25% depending on the desired level of penetration. Stainless steel will typically use a mix of 82% Argon and 18%
C02. Other mixes are used to achieve different results.
Aluminum
In general, all plate alloys of the 1100, 3000, and 5000 series are considered excellent for stud welding; alloys of the
4000 and 6000 series are considered fair; and the 2000 and 7000 series are considered poor. Most aluminum weld studs
are manufactured from 5000 series aluminum.
Base Metal Preparation
Base metal to which studs are to be welded should be free of anodic coatings, moisture or other foreign material to
assure obtaining sound welds. These areas may be cleaned by etching, brushing with a stainless steel bristle brush, scraping
or grinding.
Prior to welding, surface areas to which studs will be welded should be clean and free of foreign matter including the
following:
(1) Paint
(2) Moisture
(3) Heavy oxide film
(4) Oil, grease, indelible markings, etc.
(5) Anodic coatings
Cleaning may be accomplished by mechanical means (milling, stainless steel wire brushing), chemical methods, or both. Oil,
grease, and similar contaminants should be removed with a suitable, safe solvent. (The use of chlorinated hydrocarbons
should be avoided.) A heavy oxide film may require removal by chemical means. Welding should take place within eight
hours after cleaning.
electrical Arrangements.
Arc stud welding of aluminum should be performed with direct current, electrode positive (DCEP). This is the opposite
of standard stud welding. For aluminum, the weld tool should be connected to the RED output terminal and the ground
should be connected to the BLACK output terminal.
CAUTION
Special Welding
Stud Welding using DCEP (direct current, electrode positive) SHOULD NOT be used
in multi-weld tool mode. If you have a multi-weld tool unit and need to weld aluminum
or other material studs using DCEP, only connect 1 weld tool. NEVER MIX electrode
positive (DCEP) and electrode negative (DCEN) on this stud welder.
Techniques
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