Evolution of Boiler tube materials
Power Plant heat rate is directly related to Boiler technology and its metallurgy. Over the years of research and development boiler materials are improved to withstand hi temperature stress and corrosion environment. Basically it has divided into four generation of steel depending upon the creep strength. We can see in the below curve development of steel w.r.t creep strength from the year of 1920 to 2000 Generation Years Alloy Modifications Strength 105 hr Creep Rupture Achieved kg/cm2 Example Alloys Maximum Metal Use Temp. °C 1 1960-70 Addition of Mo or Nb, V to simple 12Cr and 9Cr Mo steels 611.82 EM 12, HCM9M, HT9, Tempaloy F9.HT91 565 2 1970-85 Optimization of C, Nb.V 1019.71 HCMI2.T91, HCM2S 593 3 1985-95 Partial substitution of W ...