300 Prakt. Met. Sonderband 38 (2006) 
* The results obtained at 620°C correlate with the data reported in the literature and 
found in the present microstructure. This consists of a recrystallized ferritic matrix 
with tempered martensite and bainite, in which the cementitic carbides are 
replaced by a fine dispersion of Mo carbides contributing to structural hardening 
(similar to secondary hardening) without impairing ductility. 
The normalized samples show the typical behaviour of martensite-ferrite dual- 
phase steel, with a smaller fraction and size of martensitic islands with respect to 
HR steel. 
ACKNOWLEDGEMENTS 
The authors wish to express their special thanks to the University of Oviedo International 
Office for the concession of a study grant to Mr. Julio Panta for the April-May 2006 period. 
We also wish to express our gratitude to ACERALIA for the granting of access to the 
facilities in their HR laboratory. Our special gratitude is extended to all the factory 
engineers involved in the project, in particular to J. Galvez-Carrobles, Dip Eng, promoter 
of the joint research project between the University of Oviedo and ACERALIA, in charge 
of the development of HR multiphase steels, and to Valeriano Barrén-Dopazo Dip Eng, 
and M. Malanda, Dip Eng, both belonging to the HR Quality Department of ACERALIA- 
Aviles for their invaluable help in many technical and non-technical issues. Lastly, we 
likewise wish to express our gratitude to all the personnel at the hot roll and pickling 
department of ACERALIA-Aviles involved in this project. 
REFERENCES 
[1] Llewellyn D., and Hillis D., “ Dual phase steels ”, The Institute of Materials. 
Ironmaking and Steelmaking 1996 Vol.23 N° 6. 
[2] Pero-Sanz J., “ACEROS, Metalurgia Fisica, Seleccién y disefio”. Editorial Dossat, 
2004, 1 ed. pp. 326-331. 
[3] Apraiz J., “Heat treatments of the steels” Editorial Dossat 2000, 92 ed., pp. 76-87. 
[4] NORMA ESPANOLA, “Materiales metalicos — Ensayos de traccion, parte 1: Método 
de ensayo a temperatura ambiente” UNE-EN10002-1. AENOR, Madrid. Espafia, 
2002. 
[5] Pickering F., “Physical Metallurgy and the Design of Steels”, (Applied Science Pub. 
1983) 
[6] LePeraF., “Técnica mejorada de ataque para la determinacion del porcentaje de 
martensita en aceros de fase dual de alta resistencia’, Metallography and 
International Journal, National Steel Corporation, 1979. 
[71 Lanzillotto C., and Pickering F., “Structure-property relationships in dual phase 
steels”, The Metals Society, Metal Science, Vol. N° 16, August 1982 
[8] Asensio J., Materials Engineering Course, Spain: The School of Mines of Oviedo: 
Academic Year 2003-2004