About Guardian TMT

Hot steel billets are rolled through Roughing, Intermediate and Finishing stands passes of final product in the rolling mill to the final size and shape of the reinforcement bar. At this stage the bar is processed for Quenching and Tempering by Thermex®️ German technology process. The process is carried out in three successive stages as described below.

The first stage begins as soon as the bar leaves the final mill stand. The bar is rapidly and energetically cooled (Quenched) with water through a short cooling installation, where it undergoes surface hardening (Marten site layer). At this stage the surface layer is converted into Marten site while the core remains Austenitic.

The second stage begins as soon as the bar leaves the quenching pipe. At this point the temperature of the core is higher than the temperature of the surface. Due to this temperature gradient heat starts flowing from Core to the Surface thus tempering the Marten site layer formed in the first stage. Due to this the surface layer is Tempered by using the residual heat left in the Core of the bar (self Tempering of the Marten site layer). The core is still in the Austenitic phase at this stage.

In the third stage atmospheric cooling of the Reinforcement bar takes place on the cooling bed. Here the Austenitic structure is transformed into a ductile Ferite - Pearlite structure. The final structure consists of ductile Ferrite-Pearlite structure in the core and strong tempered Marten site structure in the outer layer at the surface. This gives the reinforcement bars a unique property of strength in combination with ductility.