This part of IS0 4950 specifies the chemical composition and the mechanical properties of high yield strength flat steel products supplied in the quenched and tempered condition. For the method of manufacture, acceptance conditions and marking of these products, see IS0 4950-I. It is applicable to hot-rolled plates and wide flats having a width greater than or equal to 600 mm, in the thickness range 3 mm to 70 mm, in steel which, after quenching and tempering, has a minimum specified yield strength of 460 N/mm2 to 690 N/mm2 for thicknesses less than or equal to 50 mm, and 440 N/mm2 to 670 N/mm2 for thicknesses between 50 mm and 70 mm. This part of IS0 4950 does not apply to products covered by other standards, such as plates for pressure vessels (see IS0 9328-4).