©
COPYRIGHT 1999 THE ESAB GROUP, INC. LESSON
I, PART A create
welding difficulties. 1.7.3
Manganese
- Manganese in contents up to 1% is usually present in
all low alloy steels
as a deoxidizer and desulphurizer. That is to say, it readily combines with
oxygen and sulphur
to help negate the undesirable effect these elements have when in their natu-
ral state. Manganese also increases
the tensile strength and hardenability of steel. 1.7.4
Chromium
- Chromium, in combination with carbon, is a powerful
hardening alloying
element. In addition to its hardening properties, chromium increases corrosion
resistance and the strength of steel
at high temperatures. Chromium is the primary alloying
element in stainless steel.
1.7.5
Nickel
- The greatest single property of steel that is improved
by the presence of nickel
is its ductility or notch toughness. In this respect, it is the most effective
of all alloy- ing
elements in improving a steel's resistance to impact at low temperatures. Electrodes
with high nickel content are used to
weld cast iron materials. Nickel is also used in combi-
nation with chromium to form a group
known as austenitic stainless steel. 1.7.6
Molybdenum
- Molybdenum strongly increases the depth of the hardening
characteristic of steel. It is
quite often used in combination with chromium to improve the
strength of the steel at high temperatures.
This group of steels is usually referred to as chrome-moly
steels. 1.7.7
Silicon
- Silicon is usually contained in steel as a deoxidizer.
Silicon will add strength
to steel but excessive amounts can reduce the ductility. Additional amounts
of silicon are
sometimes added to welding electrodes to increase the fluid flow of weld metal.
1.7.8
Phosphorus
- Phosphorus is considered a harmful residual element
in steel because
it greatly reduces ductility and toughness. Efforts are made to reduce it
to its very lowest
levels; however, phosphorus is added in very small amounts to some steels to
increase strength.
1.7.9
Aluminum
- Aluminum is primarily used as a deoxidizer in steel.
It may also be used
in very small amounts to control the size of the grains.
1.7.10
Copper
- Copper contributes greatly to the corrosion resistance
of carbon steel by
retarding the rate of rusting at room temperature, but high levels of copper can
cause welding
difficulties.
