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


Final report on Contract No 7210-PR/037, 01/07/1997 to 31/12/2000

A cooperative work programme was carried out to develop a new metallurgical process, based on inclusion metallurgy, high-temperature-controlled rolling and accelerated cooling, in order to control acicular ferrite (AF) formation in HSLA steels and improve strength-toughness properties of parent plate and welded material (SAW, laser and electron beam welding).

The use of titanium in place of aluminium for killing steel before casting can produce multiphase inclusions formed by titanium/manganese oxides and manganese sulphides suitable for the nucleation of acicular ferrite in number densities of about 200 particles per square millimetre. However, for such inclusion densities, the formation of significant amounts of acicular ferrite is only possible if the austenite grain size (AGS) is greater than about 100µm. In the conventional hot rolling of plates made from titanium-killed steel, such austenite grain sizes are difficult to achieve for plate thicknesses up to 80mm (AGS from 30 to 60µm).

Consequently, for the successful formation of large quantities of acicular ferrite in plates, much larger number densities of nucleated particles must be introduced into the steel as shown by the laboratory rolling of weld metal containing 800 particles per square millimetre and 1.5µm mean diameter.

Despite the above results, it has been shown that killing with titanium instead of aluminium can produce large amounts of acicular ferrite and improve the toughness of autogenous power beam weld metal at relatively high heat input.

Additional information

Authors: ANELLI E, CSM, Rome (IT);MATERA S, CSM, Rome (IT);HARRISON P, Corus UK Ltd, Rotherham (GB);GUTIÉRREZ I, CEIT, San Sebastián (ES);DÍAZ FUENTES M, CEIT, San Sebastián (ES);PORTER D, Rautaruukki OY, Raahe (FI);HUTCHINSON B, SIMR, Stockholm (SE);ZAJAC S, SIMR, Stockholm (SE);SIWECKI T, SIMR, Stockholm (SE);GUTIERREZ I, CEIT, San Sebastian (ES);DIAZ FUENTES M, CEIT, San Sebastian (ES)
Bibliographic Reference: EUR 20215 EN (2002), pp.221. Euro: 34.00
Availability: EUR-OP reference: KI-NA-20215-EN-S Available from EUR-OP sales agents. URL:
ISBN: ISBN: 92-894-3363-9