3 Fundamentals
of Tig Welding The
power source for TIG welding may be either a.c. or d.c. However, certain distinctive
weld characteristics obtained
with each type often make one or the other better suited to a specific application.
Table 1-1 provides
a handy guide to the type of current you should use for a given job. An explanation
of the effects produced
by the two types of current, together with the reason for high-frequency stabilization
of altering current
follows:
Table
1-1 – Current Selection for ”TIG” Welding
ALTERNATING
DIRECT
CURRENT*
CURRENT
With High-
Frequency
STRAIGHT
REVERSE
MATERIAL
Stabilization
POLARITY
POLARITY
Magnesium
up to 1/8 in. thick 1
N.R.
2
Magnesium above 3/16 in. thick
1
N.R.
N.R. Magnesium
Castings 1
N.R. 2
Aluminum up to 3/32 in. thick
1 N.R.
2 Aluminum
over 3/32 in. thick 1
N.R. N.R.
Aluminum Castings 1
N.R. N.R.
Stainless Steel 2
1
N.R. Brass
Alloys 2
1 N.R.
Silicon Copper
N.R.
1 N.R.
Silver
2
1 N.R.
Hastelloy Alloys 2
1
N.R. Silver
Cladding 1
N.R. N.R.
Hard-Facing
1 1
N.R. Cast
Iron 2 1
N.R. Low
Carbon Steel, 0.015 to 0.030 in.
2** 1
N.R. Low
Carbon Steel, 0.030 to 0.125 in. N.R.
1 N.R.
High Carbon Steel, 0.015 to 0.030 in.
2
1 N.R.
High Carbon Steel, 0.030 in. and up
2 1
N.R. Deoxidized
Copper*** N.R.
1 N.R.
Titanium N.R.
1 N.R.
KEY: 1. Excellent operation. 2. Good operation.
N.R. Not recommended. *Where
a.c. is recommended as a second choice, use about 25% higher current than is recommended
for DCSP. **Do not use a.c. on
tightly jigged part. ***Use brazing flux or silicon bronze flux for 1 /4-in. and
thicker.
