Toughness anisotropy in X70 and X80 linepipe steels

Abstract

The anisotropy of mechanical properties in the context of steels used to fabricate large diameter pipes can be detrimental to the design and performance of the pipes. We examine here the anisotropy of strength and toughness, and with the help of detailed characterisation show that there is a complex interaction between the ability of the steel to delaminate on the rolling plane and the crystallographic texture, which promotes brittle fracture on the macroscopic fracture plane of Charpy specimens.

Keywords:

• Linepipe steels
• Anisotropy
• Charpy toughness
• Crystallographic texture
• Mechanism of anisotropy

Acknowledgements

The authors are grateful for support from the POSCO Steel Innovation Programme and to the World Class University Programme of the National Research Foundation of Korea, Ministry of Education, Science and Technology, project no. R32-2008-000-10147.