Modified master curve of ultra high strength steel

The classical Master Curve approach covers the ferritic steels with a yield strength range of 275 MPa–825 MPa. The ultra high strength steel S960 QC is out of this range, and it does not follow the formula determined in the ASTM E1921-05 Standard. In this paper, the results of the research program are presented, and a new Master-like curve is derived. The new curve preserves the basic features of the classical Master Curve; it simply widens the family of Master Curves.

► Fracture toughness of the S960 QC steel was analyzed at the ductile–cleavage transition region.
► The S960 QC steel does not follow the classical Master Curve equation.
► No thickness effect on fracture toughness was observed in the thicknesses range tested.
► New Master Curve for the ultra high strength steel was determined.