Page 170 - CITS - Welder - Trade Theory

WELDER - CITS

Welding wires used in CO welding, diameter, Specification
2
Objectives: At the end of this lesson you shall be able to
• describe the GMAW consumable wire
• explain the GMAW wire chemical composition
• explain the GMAW wire selection in welding.

Electrode wire - consumable wire for GMAW: Performance & metal transfer characteristics are largely
governed by the diameter of the wire and the machine settings such as arc voltage and amperage and chemical
properties of the filler wire employed.
Machine settings: Diameter of the wire and ampere/ current employed for welding decide the type of metal
transfer. The various recommended diameter, voltage and current ranges are tabulated in tables below for
welding mild steel, low alloy steel and stainless steel. Approx. machine settings for
a short circuit metal transfer on mild and low alloy steel

Electrode diameter(mm) voltage range Arc Amperage

0.8 16-22 80-190
1.2 17-22 100-225

b Approx. machine settings for spray arc transfer on mild and low alloy steel

Electrode diameter(mm) voltage range Arc Amperage
0.8 24-28 150-265
1.2 24-30 200-315
1.6 24-32 275-500
c Approx. machine settings for short circuit transfer on series 300 stainless steel

Electrode diameter(mm) voltage range Arc Amperage

0.8 17-22 50-180
1.2 17-22 100-210

d Approx. machine settings for spray transfer on series 300 stainless steel

Electrode diameter(mm) voltage range Arc Amperage
0.8 24-28 160-210
1.2 24-30 200-300
1.6 24-32 215-325

Chemical properties: Chemical compositions of the filler wire play a very important role. The main composition,
apart from the major elements, in the case of mild steel welding, will contain deoxidisers like Si, Mn to take of care
of porosity due to oxidation of carbon in the steel. Typical composition of mild steel filler wires are listed in the
table. We are using ER70S-6 for most of our carbon steel fabrication.
Specification of electrode wires
The GMAW electrode specification as per AWS is as given below.

Eg: E 70S-2 or ER70S-2 or E70T-2
E - Electrode
ER - Electrode can also be used as a filled Rod in GTAW.
70 - 70 x 1000 PSI - Tensile strength of the weld metal

in pounds per square inch.
S - Solid wire / Rod

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CITS : C G & M - Welder - Lesson 49 - 60