Title

MINIMIZATION OF SURFACE DEFECTS ON BARS AND WIRE ROD ORIGINATED IN BILLET CASTING

MINIMIZATION OF SURFACE DEFECTS ON BARS AND WIRE ROD ORIGINATED IN BILLET CASTING

Authorship

GENZANO, CRISTIAN; REDA, LUIS PABLO; MADIAS, JORGE

GENZANO, CRISTIAN

I am this author

REDA, LUIS PABLO

I am this author

MADIAS, JORGE

I am this author

DOI

10.5151/2594-5300-3006

Downloads

Abstract

In order to minimise surface defects in long products, their origin needs to be assessed. To this purpose, a methodology was developed, that includes metallographic studies on bar and wire rod using several reagents. A description is made of the different steps involved in this method, including the use of etchants to determine the former position of the defect in the billet, oxygen penetration, etc. It is also discussed the interpretation given to internal oxidation, scale inside the defect, decarburisation, partial welding and other metallographic features. A discussion of pin holes and transverse cracks on billets is made, taking into account its aspect and metallographic features on the billet, the evolution during reheating and rolling and the final aspect and metallographic features on the bar/wire rod. Root causes for formation of these defects and solutions recommended are analysed for each case. The paper is based on experience made by IAS Technical Centre while troubleshooting defect problems in carbon steel long products at South American steel plants.

In order to minimise surface defects in long products, their origin needs to be assessed. To this purpose, a methodology was developed, that includes metallographic studies on bar and wire rod using several reagents. A description is made of the different steps involved in this method, including the use of etchants to determine the former position of the defect in the billet, oxygen penetration, etc. It is also discussed the interpretation given to internal oxidation, scale inside the defect, decarburisation, partial welding and other metallographic features. A discussion of pin holes and transverse cracks on billets is made, taking into account its aspect and metallographic features on the billet, the evolution during reheating and rolling and the final aspect and metallographic features on the bar/wire rod. Root causes for formation of these defects and solutions recommended are analysed for each case. The paper is based on experience made by IAS Technical Centre while troubleshooting defect problems in carbon steel long products at South American steel plants.

Keywords

Surface defects, Billet casting, Wire rod, Metallography, Carbon steel

Surface defects, Billet casting, Wire rod, Metallography, Carbon steel