PRODUCTION OF FERRITIC IRON-BASE ALLOY, AND HIGH CHROMIUM FERRITIC HEAT RESISTANT STEEL

摘要

PROBLEM TO BE SOLVED: To efficiently produce an iron-base alloy and a ferritic heat resistant steel by designing the iron-base alloy and the ferritic heat resistant steel by the prediction using the molecular orbital theory and to obtain a heat resistant steel having properties superior to the existent heat resistant steels of the same kind and suitably used for boiler. ;SOLUTION: With respect to various elements in an iron-base alloy of body- centered cubic crystal, the (d) electron orbit energy level (Md) and the bond order (Bo) to iron are determined by the DV-Xα cluster method, and a chemical composition is determined so that the average Bo value, represented by equation (average Bo value) = ΣXi.(Bo)i, and the average Md value, represented by equation (average Md value) = ΣXi.(Md)i, are regulated to 1.805-1.817 and 0.8520-0.8628, respectively, where Xi means the molar fraction of an alloying element (i) and (Bo)i and (Md)i mean the Bo value and Md value of the element (i), respectively. Prefered boiler steel is a ferritic heat resistant steel which contains, by weight, 9.0-13.5% Cr, 0.02-0.14% C, 0.5-4.3% Co, and 0.5-2.6% W and in which the average Bo value and the average Md value are within the area enclosed with a line connecting the points, A, B, C, and D in the figure.;COPYRIGHT: (C)1997,JPO