TMT Steel Bar

Manufacturing Process

Production of Panchakanya TMT Steel bar (Thermo-Mechanically-Treated Bars) was started in the year 2002 through the latest German Technology. Panchakanya TMT Bar a new generation high strength ribbed reinforcement bar manufactured with Thermo Cooling Technology and Licensed under Chemistries Stethi Engg. GmbH (HSE) Germany.

Quenching:

First stage in the production stage is better termed as quenching. Hot rolled bar passes through a water cooling system where it comes in contact with HIGH FORCE WATER SPRAY (JET VELOCITY OF WATER). The Surface temperature of the bar is reduced from 1000 to 300 degree centigrade in a fraction of second. This process convert's a surface layer of the bar into hardened structure known, as "Marten site" while the core remains austenitic.

Self-Tempering:

Second stage begins when the bar leaves the quenching box with the temperature of the core higher than that of the surface. In this stage heat flows from the core to the surface, resulting in the tempering of surface, giving a structure called "Tempered Martensite". At this stage, the core still remains austenitic. Only the surface of the bar gets quenched & hardened which subsequently gets self-tempered by the heat from the core.

Atmospheric Cooling:

Third stage is completed on the cooling bed, where the austentic core is transformed into a ductile ferrite-pearlite core. Thus the grain structure consists of a combination of tough outer layer of tempered Martensite and a ductile core of ferrite-pearlite.

Concept and technology of TMT steel bars have been developed and patented by M/s. Hennigsdorfer StahI Engg. GmbH, famous THERMEX® technology developer of Germany. TMT steel bars do not require cold twisting after hot rolling. These bars gain hardening & tempering during hot rolling.. The combination of tempered Martensite on the surface and ferrite +fine pearlite in the core provides considerably "higher strength & ductility" to the finished material, making it ideal for building structures especially in earthquake prone areas, bridges construction, hydro power projects etc.

(Thermex® Cooling Technology involves subjecting the bar to pre-determined quality of high-pressure water after the last rolling mill stand. This treatment converts the bar surface to a hardened structure. The subsequent phase involves cooling at ambient temperature to allow the hot core to temperature surface through thermal exchange. This results in a unique structure of tempered Martensite peripheral zone and a fine grain ferrite-pearlite at the central zone.