Effect of Carbon on
Increase in carbon in steel:
1) Decreases the ductility of steel.
2) Increases the tensile strength of steel
3) Increases the hardness of steel.
4) Decreases the ease with which steel can be
5) Lowers the melting point of steel.
6) Makes steel easier to harden with heat
7) Lowers the temperature required to heat
8) Increases the difficulty of welding steel.
Steel with 0.2% Carbon can attain Rockwell C
hardness of 49, while an 0.8% carbon steel can
be hardened to Rockwell C of 65.
As carbon is added, steel gets harder and
becomes difficult to machine,
Melting point of 0.2% carbon steel is 2800°F
while 0.8% carbon steel can melt near 2,700°F.
Steel are classified according to their carbon
content. Carbon will dissolve into iron without
producing steel at 0.026% at 1330°F.
Low carbon steel or mild steel contain less
than 0.3% carbon. Medium carbon steels contain
carbon from 0.3 -0.55%. High carbon steel
contain more than 0.5% carbon. Iron with more
than 2% carbon is referred to as Cast Iron.
Steels for springs must have at least 0.45 %
carbon to attain required hardness.
Plain Carbon steel such as 1045, 1060, 1074,
1080 or even 1095 can be used for springs but
become rather brittle at higher carbon content.
Plain carbon steel are used for flat springs.
The alloyed steels such as 6150, 9260 and 8650
are recommended because of their added
toughness. A 302 stainless steel is often used
for springs that have higher temperature