Tempcore Technology & Process |
ATLAS
TMT bars are produced and successfully marketed by J.M.G.
Steel Private Limited using the world renowned ‘TEMPCORE
Process’ under the license from Centre de Rechaerche Metallurgiques
(CRM), Belgium. The Tempcore process consists of a special thermo
mechanical process which involves quenching the surface layer of the
bar and subsequently tempering the outer layer by the heat of the
core, thus producing a high strength bar.
Under thermo mechanical treatment (TMT), our
steel bars are passed through a specially designed water-cooling
system where they are kept till the outer surface of the bars
becomes colder while the core remains hot. This creates a
temperature gradient in the bars. When the bars are taken out of the
cooling system, the heat flows from the core to the outer surface,
further tempering of the bars, which helps them attain higher yield
strength. The resulting heat-treated structure imparts superior
strength and toughness to the bars. The microstructure of the core
is a very fine-grained ferrite and pearlite.
ATLAS TMT bars are 'hot rolled' from steel billets/ingots and then
subjected to a PLC controlled on-line thermo mechanical treatment in
three successive stages:
Quenching
Quenching is generally done by cooling at a sufficiently high
rate to avoid undesirable internal microstructure as well as to
ensure uniform mechanical properties, minimize residual stresses,
and avoid warpage.
Tempering
Tempering is done to toughen the metal by transforming brittle
martensite into tempered martensite. As the bar leaves the quenching
box and is subjected to air-cooling, the core remaining hot compared
to the outer surface allows heat to flow to the surface, causing
tempering of the outer martensitic layer into a structure called
Tempered Martensite.
Atmospheric Cooling
This takes place on the cooling bed where austenitic core is
transformed into a ductile ferrite-pearlite core.
The final structure consists of an optimum combination of a
strong outer layer (tempered martensite) with ductile core (ferrite-pearlite);
giving ATLAS TMT bars a unique combination of higher strength and
ductility. |
