THERMEX technology by the German major Hennigsdorfer Stahl Engineering (HSE) is used in our manufacturing process.
About the technology
The THERMEX cooling technology involves subjecting the bar to a predetermined quantity of high pressure water off the last rolling mill stand. Air and Water pressure is automatically controlled by the PLC system from ABB, based on the size, speed and temperature of the rod. This treatment converts the bar outer surface to a hardened structure. The subsequent phase involves cooling at ambient temperature to allow the hot core to tamper the surface through thermal exchange. This results in a unique structure of tempered martensite in the peripheral zone and a fine grain of ferritepearlite at central zone. The results are a world-class QST Rebar.
During the last few years the civil engineering sector has increased its demand for low-cost reinforcing steel bars with guaranteed minimum yield point characteristics of 500 MPa. This need arose since these steel grades are covered by the relevant standard specifications of all developed industrial countries. The use of such Grade500 high strength rebars reduces civil construction cost because of
- Saving in reinforcement
- Reduced labour costs
- Lower transport costs
- Easy processing due to high weldability
Steel bars with a minimum yield point of 500 MPa is close to the upper limit for normal rebars used in reinforced concrete.
Cold twisted deformed (CTD) rebars were developed about 30 years ago to obtain high strength rebars as a cheap alternative to the use of costly alloying elements such as Cr, Ni, V, Nb, Ti. But the CTD rebars sacrificed the two essential properties of weld ability and elongation and hence are not used in developed countries - whereas they became popular in India and the neighboring countries.
THERMEX QST REBARS
The development of the patented THERMEX Cooling Technology has been a great boon to the civil industry the world over as an acceptable alternative to the use of rebars made from steel alloyed with costly elements. The Indian Region, where CTD rebars has had a stranglehold for the past 2 - 3 decades, is today waking up to the benefits of the Thermex rebars primarily on account of
- Superior product with consistent properties
- High strength combined with high ductility
- Better corrosion resistance
- Better resistance to high temperatures, as in the case of fires
- Easy manufacture of different strengths of rebars from nearly the same steel grades
- Saving of 10-20% in steel consumption when using Thermex 500 in place of CTD rebars
- Better fatigue resistance
- Better weldability
- Easy and less construction time
- Lastly, an ideal choice for seismic zones due to excellent ductility properties.
This is of great importance for India because nearly 60% of the country falls in the high seismic hazard category.
Most importantly, the Thermex Cooling System is an in-line process and the high strength Thermex rebars are ready for despatch to the customer almost immediately after rolling is complete – unlike the few days taken in the case of CTD rebars which results in large inventory levels in the mill.