Keerthiprasad.K et al. Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 6 Version 1, June 2014, pp.136-146
www.ijera.com 137|P a g e
The required strength level, such as high or low tensile strength steel
The heat treatment, such as annealing, quenching and tempering steel.
1.2.1 Carbon Steels
Carbon steel is an iron-based metal containing carbon up to 2, and small amounts of other
elements Mn, Si, S, and P. Variations in carbon have the greatest effect on mechanical properties,
with increasing carbon content leading to increased hardness and strength. As such, carbon steels are
generally categorized according to their carbon content. Generally speaking, carbon steels can be
subdivided into low-carbon steels, medium-carbon steels and high-carbon steels
1.2.2 Low Carbon Steels
Of all the different steels, those produced in the greatest quantities fall within the low-carbon
classification. These generally contain less than about 0.25 wt C and are unresponsive to heat treatments
intended to form martensite; strengthening is accomplished by cold work. Microstructures consist
of ferrite and pearlite constituents. As a consequence, these alloys are relatively soft and weak, but have
outstanding
ductility; in
addition, they
are machinable, weldable, and, of all steels, are the least
expensive to produce. Typical applications include automobile body components, structural shapes I-
beams, channel and angle iron, and sheets that are used in pipelines, rivets, nails and others. Plain low-
carbon steels have yield strength between 180 and 260 MPa , tensile strengths between 325 and 485
MPa , and a ductility reach to 25EL. 1.2.3 Medium-Carbon Steels
The medium-carbon
steels have
carbon concentrations between about 0.25 And 0.60 wt.
These alloys may be heat treated by quenching, and then tempering to improve their mechanical
properties. They are most often utilized in the tempered condition, having microstructures of
tempered martensite. The plain medium-carbon steels
have low hardenability’s and can be successfully heat treated only in very thin sections and with very rapid
quenching rates. Applications include railway wheels and, gears, crankshafts, and other machine parts.
1.2.4 High-Carbon Steels
The high-carbon steels, normally having carbon contents between
0.60 And 1.4 wt, are the hardest, strongest, and yet least ductile of the carbon steels. They are almost
always used in a hardened and tempered condition and, as such, are especially wear resistant and
capable of holding a sharp cutting edge. Application includes blacksmith tools and wood working tools.
1.2.5 Alloy Steels
