9.5%Cr steels

9.5%Cr martensitic steels have been developed that are capable of withstanding the higher steam temperatures and pressures which are needed to achieve an increase in the thermal efficiency of fossil fuel fired power generation plants. Many of these alloys were developed during the European COST 501 programme.

Temperatures up to 620°C require the use of these steels with improved creep rupture strength over and above those of the conventional CrMo and CrMoV steels.

Higher creep and stress rupture strength is obtained by the addition of various combinations of nickel, molybdenum, tungsten at levels around 1% together with small additions of nitrogen and niobium. Work is being carried out with cobalt and boron additions.

Goodwin manufactures  a number of grades of 9.5%Cr steels. The cast equivalents of the wrought ASTM P91 (1%Mo - ASTM A217:C12A), E911 (1%Mo 1%W - GX12CrMoWVNbN1011) and the 0.5% nickel GE B50A349 grade are commonly supplied.