The TEMPCORE™ Process has been developed in the early seventies by CRM Group in order to manufacture high strength & weldable concrete reinforcing bars (”rebars”) from mild steel, without adding costly alloying elements. It consists in subjecting the hot rolled steel to an in-line heat treatment in 3 successive stages:
When leaving the final mill stand, the product is rapidly and energetically cooled through a short cooling installation, where it undergoes surface hardening (martensite layer)
As soon as this quenching operation is stopped, the surface layer is Tempered by using the residual heat left in the CORE of the bar (self-tempering of the martensite layer); hence the name TEMPCORE™. The process ensures uniform formation of the wall-thickness of each layer all throughout the Rebar (as shown in the Ring-test image below).
The third stage takes place while the product lies on the cooling bed where the bar is subjected to normal cooling down to ambient temperature (transformation of the residual austenite in the core)
TEMPCORE™ is the best process for the production of high quality rebars. Costly alloying elements (Vanadium, Niobium) are replaced by low-cost … water! It allows obtaining from low C-Mn steel concrete reinforcing bars with high mechanical properties (World-Class Standards) excellent Weldability and superior ductility and bendability
The TEMPCORE™ technology
Each TEMPCORE™ equipment is designed by CRM Group on the basis of precise calculations complemented with a very large experience (more than 70 mills equipped around the world, for rebar diameters up to 75 mm). Such design guarantees excellent process controllability (giving consistent product properties) and high flexibility (allowing to produce several grades with the same chemistry). Equipment manufacturing is then often carried-out locally at low cost.
The Certification process is very stringent as CRM is a research organization funded by ArcelorMittal group with a primary objective of uncompromised quality, which maintains a close Quality compliance post certification as well. Till date a very small percentage of Steel Rolling-mills, worldwide have been able to make it through their process.