Effects of Alloying Elements on Mechanical and Metallurgical Properties of Cr-Mo-V-Ti-B Pressure Vessel Steels

Abstract

Recently, larger and thicker reactor vessels have been required in hydrogenation processes in order to search the scale merit and to upgrade the service temperature and pressure. The objective of the present work is to develop a heavy-section Cr-Mo pressure vessel steel with enhanced design stress intensity and higher resistance to hydrogen attack, by conducting a set of experiments with regard to the effect of micro alloying elements.
Effects of Cr, Mo, V, Ti, B and Si were investigated on various properties such as hardenability, tensile strength, impact toughness, creep rupture strength, hydrogen attack susceptibility and weldability. As a results of this alloy modification program, the best composition was found out to be low Si-3%Cr-1% Mo-1/4% V-Ti-B.