04 July 2020

Interview- Radhika Markan (H&K Rolling)

Thermex® 500 grade rebar exceed those defined in the Indian Standard 


Mumbai based H&K Rolling Mill Engineers Pvt. Ltd. (H&K India) introduced THERMEX®, the proprietary Quenching and Self Tempering technology, to the country’s steel industry in 1985. Radhika Markan, Managing Director, H&K Rolling Mill Engineers Pvt. Ltd – she is also CEO, Thermex Rebar Manufacturers’ Association (TRMA) – dilates on the technology in an interview to CONSTRUCTION OPPORTUNITIES


Your company pioneered the launch of QST rebar technology in India. Tell us about the journey so far? 


H&K Rolling Mill Engineers Pvt. Ltd. (H&K India) was specifically formed in 1985 to introduce relevant and modern technologies into the Indian steel industry.  Soon after its formation, the company successfully undertook modernisation of the rolling mills of Kalyani Steels at Pune and the Durgapur Steel Plant and Bhilai Steel Plant, both belonging to SAIL. Grip and trough tilters, stop-start shears, bundling and binding facilities and the patented Thermex® Quenching and Self Tempering (QST) System were some of the equipment and technologies introduced by H&K India in these projects.


Give us an understanding of Thermex ® QST technology?


Thermex® QST technology of Hennigsdorfer Stahl Engineering Gmbh, Germany is the world’s leading QST technology. It gained immediate global acceptance because of its simplicity and ease of operation. Thermex® systems are installed worldwide, ranging from Asia, Australasia, Europe, Russia, Africa and the Americas. HSE Germany has granted exclusive and perpetual rights to H&K India to supply and install Thermex® systems in the Indian sub-continent. In our region alone we have almost 190 Thermex® projects commissioned or in the commissioning phase.


What are the advantages of this technology?


Thermex® QST technology enables production of desired high-strength steel rebars that meet all requirements of civil construction - yield strength ranging from 500MPa or more, toughness, ductility, weldability and excellent bend properties.


The Thermex® process has two major steps.


Quenching - A short, intensive but very precise in-line cooling of the rolled bar is imparted through proprietary equipment, and this treatment results in a hardened periphery without any major effect on the core.


Tempering - The bars are allowed to cool naturally on leaving the proprietary quenching pipes. At this stage a thermal exchange (THERMEX) occurs between the hot inner core and the quenched martensite surface whereby the resultant bar structure is a distinct tempered martensite at periphery and a fine grained ferrite-pearlite structure in the central zone. The Thermex® bar so produced has unique qualities of high strength, toughness and ductility with elongation (A5) values of 18 to 25 per cent.


Tell us what necessitated the introduction of this technology here in India?


A large part of India falls within seismic zones 3, 4 and 5. Furthermore, some of India’s top cities are built on fault lines. Such a scenario or background mandates the use of high-strength, high-ductile rebars with superior elongation values of 18-25 per cent for building structures. Unfortunately for India, from 1970’s onwards until 1990’s cold-twisted deformed (CTD) bars were in use. Now these bars suffer from very low ductility and high corrosion, making them unsuitable for Indian construction requirements. This alone was the reason the patented, German Thermex® technology was introduced in India. And this also is the reason it became a runaway success in India. Very simply put, Thermex® technology fulfilled a long-standing requirement of the civil construction industry. It ensured the production of desired high-strength steel rebars that met all requirements - high-strength bars (YS ranging from 520 to 620N/mm2) with excellent ductility required for seismic India (Stress ratio ranging from 1.15 to 1.3 and elongation ranging from 18 – 25 per cent). Here I would like to stress that the properties of a Thermex® 500 grade rebar exceed those defined in the Indian Standard (IS) and in fact meet international standards.



The industry code for rebars in India is regarded as complex and not in conformity with global standards. What is your take on that?


The Indian Standard Code is too complicated for rebar manufacturers whereas it should have been made simpler. The IS must be urgently revised to keep pace with global standards. I find it quite strange that one has different chemical compositions for different grades. I am also not able to understand why one needs to have so many grades. This is not practical and will only confuse structural engineers. So, in practice it will hardly be followed at the ground level. In my opinion the Code should specify the same level of high ductility for rebars irrespective of the yield strength, as is specified in the codes of European countries. The Indian Standard code gives importance to elongation at fracture instead of uniform elongation of rebar. This poses a grave risk to residents of buildings in high seismic hazard places. Other countries have already shifted to uniform elongation since the past 5 years – which is the correct option.


The rebar business can grow on the strength of increase in per capita consumption which is way behind China. What are the steps needed to be taken to increase per capita consumption of steel in the country vis a vis our neighbour?


To catch up with China will take a decade or more because the per capita consumption of steel in China has been around 300 kg two years ago whereas it is only about 75-80 kg in India. So we will have to raise our consumption to 4 times the present level. In the present market scenario and with the government policies of the past 5 years it appears to be a near impossible task at least in the near future.


We may have to totally reverse the policies in India and take a leaf out of China – build many mega cities with a population of about 1 to 10 million each. I do not see this happening in the short term because of land acquisition and market related issues.  Infrastructure has literally slowed down and industry captains have only received the ‘wrong signals’ about government policies and hence are not prone to invest with any degree of confidence. I estimate that after the 2014 elections stability may return if the polls throw up positive results. That is an essential first step for any degree of confidence to return to the business circles.


Action on the ground by way of massive investment in infrastructure projects – roads, power, sea and air ports, railways, housing, etc will send the correct signals for manufacturing and industrial activity to re-start. Then will come the mega cities, many of them. That will lead to the per capita steel consumption increasing to over 250-300 kg which is the minimum level for a ‘developed’ country. That will be a good ten years from now, say 2024-25.              


Thermex® is the registered trademark of H&K Rolling Mill Engineers Pvt. Ltd. in India. This follows a collaboration agreement of the company with Hennigsdorfer Stahl Engineering Gmbh, Germany which granted the H&K Rolling Mill Engineers the exclusive right to market and install Thermex ® Systems and grant Thermex ® license rights to rolling mills in the Indian subcontinent. Thermex ® technology has found usage for RCC in homes, apartments, high-rise buildings, hospitals, and offices, hotels, dams, bridges, infrastructure projects, stadiums, halls, auditoriums and in earthquake area constructions It is become common practice for all major users in the country – this includes government departments, leading construction firms, municipal corporations, reputed builders of residential apartments to specify Thermex® by name in their tenders.

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