GB497010A - Chromium-manganese-nickel steel - Google Patents

Abstract

An iron alloy contains 16-22 per cent of chromium, at least 5 per cent of manganese, 3-6 per cent of nickel, the manganese content exceeding the nickel content and the total manganese and nickel content not exceeding 14 per cent, not more than 0,15 per cent of carbon, and 0,25-1,5 per cent of niobium or 0,25-2 per cent of tantalum or 0,25 per cent to a proportionate maximum of niobium and tantalum. The alloy may also contain 0,25-2 per cent of copper and the niobium or tantalum content may be at least four or six times, respectively, the carbon content; preferably, the niobium content is at least ten times the carbon content. The alloys may be employed for articles designed to withstand corrosive media during or after exposure to elevated temperatures below 900 DEG C., and, particularly, for fusion-welded articles used to withstand corrosive media. One specific example of such an alloy also contains 0,4 per cent of silicon. Specific examples are also given of similar alloys not containing nickel, not containing niobium or tantalum, and not containing nickel, niobium or tantalum. Heat treatments of such alloys and of alloys in accordance with the invention are referred to comprising quenching from 1150 DEG C., holding for 3 days at 550 DEG C. or 650 DEG C., and air cooling. Specifications 366,060, 388,057, 476,413, and 480,929 are referred to.