GB1339647A - Iron alloy - Google Patents

Abstract

1339647 Iron alloys GONTERMANNPEIPERS GmbH 22 Jan 1971 3001/71 Heading C7A An iron alloy consisting of, ELEMENT WT% Cr 18.0 - 30.0 C 1.8 - 3.5 Mn 0.5 - 2.0 Ni 0.3 - 2.0 Mo 0.2 - 0.8 Si 0.3 - 0.8 S max. 0.03 P max. 0.04 where the total amount of S and P is not more than 0.06 wt per cent and the balance is iron, and impurity is melted in an arc furnace and cooled in an accelerated manner whereby a heterogeneous fine-grained structure is obtained in which the carbides C 23 C 6 , Cr 7 C 3 , Fe 4 Cr 3 C 3 , and Fe 3 C are present in a ferritic matrix. Up to eight chromium atoms of carbide C 23 C 6 can be replaced by iron to give, with maximum substitution, Fe 8 Cr 15 C 6 . Up to two of the Cr atoms in the carbide Cr 7 C 3 can be replaced by iron to give, with maximum substitution, Fe 2 Cr 5 C 3 . The carbide Fe 3 C may take up chromium and/or manganese. After cooling the alloy is then subjected to heat treatment to give a hardness of 55-90 Shore. The alloy is used for making rollers of rolling mills, or for making their outer shells which are of a thickness of 10-15% of the overall diameter of the rollers. In the latter case a mould is filled with the alloy, a specific example of which is given. The outer shell of the alloy hardens first, and the molten core is displaced by a molten core metal such as cast iron with a 2À8 wt per cent C content or toughened steel. The alloy may alternatively be cast round a heated shaft of steel with a C content of 0À3-0À8 wt per cent or of cast iron or of cast iron with spheroidal graphite. In all cases, the roller is given heat treatment to give a Shore hardness of 72-75.