Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Stainless steel ribbed bars optimised production cycle

In view of the increasing level of development of high performance civil engineering infrastructures and the limited capacity of older structures (several years) to provide the increasingly high performance demanded by current severe environmental conditions, it becomes necessary to develop highly innovative materials in Europe. The increase in mechanical characteristics and the higher corrosion resistance within corrosive environments exhibited by stainless steel cannot be ignored, but stainless steel rebar are not used because of their initial high cost. Nowadays it is possible to find in the market some innovative low-cost High Strength Stainless Steels as the steel developed by the Hiper project.

The importance of these alloys has always been limited due mainly to their low cold working formability. Ferriere di Stabio's activity focussed on this type of steel to design a new manufacturing process by developing and improving a tools design and a forming process fit to generate ribs with the best bond strength.

Ferriere di Stabio carried out the study for the development of a suitable technology and the production trial of the innovative stainless steel to obtain rib patterns with an optimised shape to join together the brittle concrete and ductile stainless steel. Two subjects have to be matched: IR (bond strength), as defined by the technical norms, and rib shape fit to grant the best material flow to avoid surface discontinuities that can affect the ultimate tensile strength or reduce the fatigue resistance.

Within the framework of this result, Polito assessed the mechanical properties of all the materials selected in the reinforcing bar form and cold rolled state in order to provide to the consortium and, later, to all the technicians of construction sector a reliable set of data.

The properties of the cold rolled innovative products are of course highly affected by the microstructural modifications which occurred in hot rolled and annealed state. The classification of the mechanical properties in the reinforcing bar form was particularly necessary to provide a comparison with the classical reinforcing bar steel (FeB44K), which is well known product for all the construction sector. The assessment of the mechanical levels and of the stress-strain pattern is the essential base on which it is possible to design and build with such material.

These mechanical levels are currently used by other partners of the Consortium in their own activity within the HIPER project. In the future, the technicians of the construction sector will, hopefully, refer to the guidelines drawn in this project and reported in Deliverable 10 in their own day by day work of design and building.

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Ferriere di Stabio
Via Laveggio n.6
6855 Stabio
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