In order to improve the thermal efficiency of power station, it is necessary to elevate the operation temperature and pressure of boilers. This condition usually requires the usage of a large quantity of stainless steels and superalloys, which brings in an increase in construction cost and consequently in per kW power cost. Thus, it is important to develop a new kind of steel which is economical and can be a substitute for austenitic stainless steel tubing.
In the present study, the effects of molybdenium, vanadium, titanium, niobium, wolfram, cupper and boron on the creep rupture strength of medium chromium steels were investigated, and a new steel with excellent creep rupture strength, workability, and weldability was developed. The chemical composition of the new steel is low carbon-9%Cr-1%Mo-0.2%V-0.3%Nb-B, and its 100000hr creep-rupture strength is 8.0kg/mm2 at 600°C.
