Tensile specimens have been tested at room temperature, finding clear delamination in the rolling direction but only incipient delamination in the transverse direction. Delamination is found to be a strain rate-controlled process whose morphology depends on the material’s processing history, suggesting that its cause may be embrittlement induced by hydrogen occluded during processing. Delamination has only a small influence on mechanical properties in the rolling direction, but in the transverse direction a loss of ductility is detected particularly for aged specimens.

The authors acknowledge financial support from the Spanish Ministerio de Educación y Ciencia in the form of a Coordinated Project in the Energy Area of Plan Nacional 2006 (ENE2006-15170- C02). Moreover, one of the authors (J. Ch) gratefully acknowledges the contribution of Ms. C. Pe˜na for her help with the fractographic work.

Peer reviewed