Fabricator 252i basic welding – Tweco 252i Fabricator User Manual

Page 68

Advertising
background image

FABRICATOR 252i

BASIC WELDING

BASIC WELDING

4-8

Manual 0-5155

Effects of Arc Welding Various Materials

A. High tensile and alloy steels

The two most prominent effects of welding these

steels are the formation of a hardened zone in the

weld area, and, if suitable precautions are not taken,

the occurrence in this zone of under-bead cracks

may result. Hardened zone and under-bead cracks in

the weld area may be reduced by using the correct

electrodes, preheating, using higher current settings,

using larger electrodes sizes, short runs for larger

electrode deposits or tempering in a furnace.

Hydrogen controlled Electrodes must be used for

this application.

B. Austenitic manganese steels

The effect on manganese steel of slow cooling from

high temperatures is to embrittle it. For this reason it

is absolutely essential to keep manganese steel cool

during welding by quenching after each weld or skip

welding to distribute the heat.

C. Cast Iron

Most types of cast iron, except white iron, are weld-

able. White iron, because of its extreme brittleness,

generally cracks when attempts are made to weld

it. Trouble may also be experienced when welding

white-heart malleable, due to the porosity caused by

gas held in this type of iron.

D. Copper and alloys

The most important factor is the high rate of heat

conductivity of copper, making preheating of heavy

sections necessary to give proper fusion of weld and

base metal.

Arc Welding Practice
The techniques used for arc welding are almost identical

regardless of what types of metals are being joined. Natu-

rally enough, different types of electrodes would be used

for different metals as described in the preceding section.
Welding Position
The electrodes dealt with in this publication can be used

in most positions, i.e. they are suitable for welding in

flat, horizontal, vertical and overhead positions. Numer-

ous applications call for welds to be made in positions

intermediate between these. Some of the common types

of welds are shown in Figures 4-12 through 4-19.

Art # A-07687

Figure 4-12: Flat Position, Down Hand Butt Weld

Art # A-07688

Figure 4-13: Flat Position, Gravity Fillet Weld

Art # A-07689

Figure 4-14: Horizontal Position, Butt Weld

Art # A-07690

Figure 4-15: Horizontal-Vertical (HV) Position

Art A-07691

Figure 4-16: Vertical Position, Butt Weld

Art # A-07692

Figure 4-17: Vertical Position, Fillet Weld

Advertising
This manual is related to the following products: