Mass fraction of elements not more than, %: Carbon (C) 0,50-0,60; Silicon (Si) 0,10-0,40; Manganese (Mn) 0,60-0,90; Chromium (Cr) 0,80-1,20; Molybdenum (Mo) 0,35-0,55, Vanadium (V) 0,05-0,15; Nickel (Ni) 1,50-1,80; Copper (Cu) up to 0,3; Phosphorus (P) up to 0,03; Sulphur (S) up to 0,03.