1 Steel alloys in sheet or plate form, having any of the following characteristics— a steel alloys capable of ultimate tensile strength of 1 200 MPa or more, at 293 K (20 °C); or b nitrogen-stabilised duplex stainless steel. 2 In this paragraph— a “ nitrogen-stabilised duplex stainless steel ” means steel with a two-phase microstructure consisting of grains of ferritic and austenitic steel with the addition of nitrogen to stabilise the microstructure; b a reference to an alloy “capable of” something encompasses alloys before or after heat treatment.