WELDING OPERATIONS I - OD1651 - LESSON 1/TASK 1
base metal can be reduced by making the weld with a series of
small string or weave beads. Fusion between the filler metal and
the sidewalls should be confined to a narrow zone. This can be
accomplished by directing the electrode toward the previously
deposited filler metal adjacent to the side walls than toward the
side walls directly.
This procedure causes the weld metal to
wash up against the side of the joint and fuse with it without
deep or excessive penetration.
(b) When welding sheet metal up to 1/8 inch in thickness, the
plain square butt joint type of edge preparation may be used.
Heavy plates should be beveled up to 60 degrees, depending on the
thickness.
The parts should be tack welded and the root weld
made with a 1/8 to 5/32 inch electrode.
Additional passes of
filler metal should be made with a 5/32 or 3/16 electrode. Heavy
sections that have been beveled from both sides should be welded
by depositing weave beads alternately on one side and then the
other to reduce the amount of distortion in the weld structure.
(c) Small high-carbon steel parts are sometimes repaired by
building up worn surfaces.
When this is done, the piece should
be annealed or softened by heating to a red heat and cooling
slowly. Then the piece should be welded or built up with medium-
carbon or high-strength electrodes and heat treated, after
welding, to restore its original properties.
c.
Tool Steels.
(1) General.
Steels in this group have a carbon content
ranging from 0.80 to 1.5 percent. They are rarely welded by arc
welding because of the excessive hardness produced in the fusion
zone of the base metal.
If arc welding must be done, either
mild-steel or stainless-steel electrodes can be used.
(2) Welding Technique.
(a) If the parts to be welded are small, they should be
annealed or softened before welding.
The edges should then be
preheated up to 1,000, depending on the carbon content and
thickness of the plate, and the welding done with either a mild-
steel or high-strength electrode.
55
Previous Page
