Hennigsdorfer Stahi Engg. Gmbh, Germany was instrumental in developing the THERMEX Cooling System with the patented proprietory hardware for production of bars with minimum yield strength of 500N/mm2 as demanded by civil engineers. In India, H&K set up THERMEX at the DSP and BSP plants of SAIL who produce Thermex TMT bars in sizes 8 to 36 mm by this process
METRO ISPAT also entrusted the work of modernisation to H&K, the sole Indian licensee of HSE.
The Thermex Cooling Technology involves subjecting the bar to
predetermined quantity 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 temp-
erature to allow the hot core to temper the surface through thermal
exchange. This results in a unique structure of tempered martensite
in the peripheral zone and a fine grain ferrite-pearlite at the central
The result is as seen in the photo. Such a structure is the guarantee of a Thermex TMT bar.
It needs to be noted that the bar with a hardened surface needs to be cut with a special dividing shear-similar to that supplied by H&K to DSP METRO ISPAT has obtained such a shear.
The consumer of TMT rebars must ensure that they are using correct TMT rebars. This is essential today as many rolling mills in India are merely spraying water on the bars in an un-scientific way and selling them as "TMT" rebars.
THERMEX is one of two licensed processes of the world. Developed in Germany after years of research, it is the only rapid water quenching process that guarantees consistant properties over entire bar length. It is 'worker-friendly' due to its unique process and proprietary hardware. Use of the Thermax process requires no special training and is easily grasped by workers anywhere in the world.