Mass fraction of elements not more than, %: Carbon (C) 0,82-0,90; Silicon (Si) 0,20-0,50; Manganese (Mn) 0,20-0,50; Chromium (Cr) 3,80-4,40; Molybdenum (Mo) 4,80-5,30; Vanadium (V) 1,70-2,10; Tungsten (W) 5,50-6,50; Phosphorus (P) up to 0,03; Sulphur (S) up to 0,025.