PURPOSE: To enhance the hydrogen attack resistance of a steel by controlling the Sn and Sb contents to very low values and adding As and Al.

CONSTITUTION: A steel consisting of C 0.06W0.17%, Si≤0.3%, Mn 0.25W1%, Cr 1W3.5%, Mo 0.5W1.5%, sol. Al 0.009W0.025%, As 0.011W0.03%, Sn≤0.006%, Sb≤0.006%, P≤0.015% and the balance Fe. The steel of this compsn. has superior temper brittleness resistance and can maintain sufficiently high strength even at high temps.