Thermex is a simple to use unique ‘Quenching & Self Tempering’ QST Technology that was developed by Mr. Franz Tamm, Managing Director of Hennigsdorfer Stahl Engineering GMbh, located in Germany.


All Thermex® QST Systems are designed for Grade 500 as per international demands of civil engineers. The bar as it leaves the rolling mill is guided through specially designed proprietary Thermex® Pipes wherein the surface temperature of 850-1000o C is brought down drastically in a relatively short period of time on account of the intense and uniform water cooling. The temperature of the core is largely unaffected. The amount of water and time for quenching depends on the parameters of the rolling mill. This is a very important part of the engineering. The pre-determined cooling of the bar periphery transforms the peripheral structure to martensite and then annealed through the heat available at the core. The peripheral and core temperature difference finally equalizes at around 600o C and the resultant bar structure is of tempered martensite at the periphery and of fine-grained ferrite-pearlite at the core. Generally speaking, the resultant soft core forms about 65 – 75% of the area (depending upon the desired minimum yield strength) and the rest are the hardened periphery. The entire Thermex manufacturing process is operated through Computerised Programmed Logic Control (PLC) to ensure consistency in quality. Further, all GISCO Thermex TMT Bars are manufactured under stringent quality control.

It is this Thermex® QST process which results in a product with high yield strength, surface hardness, toughness, ductility and weldability.

It is also pertinent to mention here that for proper and uniform ribbing of our GISCO Thermex TMT bars, we have installed special CNC Machine in our plant to cut the ribs to the precision while manufacturing the product. This gives the property of proper bonding with the concrete cement mix. All GISCO Thermex TMT Bars are produced with in-house manufactured IS:2830 marked Ingots / Billets only. As you may be aware one of the primary advantages of using Thermex TMT bars is that buildings constructed using these bars are also earth-quake resistant to a greater extent