METHOD OF MANUFACTURING HIGH TEMPERATURE RESISTANT SHAPED PARTS

Abstract: High temperature resistant shaped parts are manufactured according to the invention by hot isostatic pressing of a powder of desired alloy composition put into a metal container. Preferably the alloy comprises 2-10 weight % aluminium, 10-40 weight % chromium, balance basically iron.

Description: Method of manufacturing high temperature resistant shaped parts. The present invention is for a method of manufacturing high temperature resistant shaped parts made of metal alloy. Metallic alloys can, when properly selected with regard to alloy composition, be used at high temperatures. High temperature is in this respect considered to be 1100°C and higher. Alloys of iron-chromium-aluminium, i.e. FeCrAl alloys, can be used at temperatures as high as 1200-1400°C and also somewhat higher temperatures. Such alloys have the advantage of being extremely resistant to oxidizing and corrosive environments at high temperatures. On the other hand the use of these alloys has been restricted due to difficulties in shaping parts of more intricate design. The method according to the present invention makes it possible to manufacture shaped parts of a high temperature FeCrAl alloy. Shaped parts are considered to be parts and products which are not in the shape of rod, strip tubes or similar which can be produced by means of extrusion of billets. Shaped parts are for example muffles, tubes, bends, crucibles and burner dies of complicated shape. The invention also comprises a suitable starting material for use in the invented method. With the present invention high temperature resistant shaped parts of FeCrAl alloy are produced from metal powder of desired composition by means of hot isostatic pressing to a predetermined shape in a metal container. The alloy preferrably contains 2-10 weight-% aluminium, 10-40 weight-% chromium, balance basically iron. The alloy can also hold small amounts of for example cobalt, nickel, silicon, manganese, zirconium, titanium, yttrium, vanadium, tantalum and rare earth metals. The present invention also includes alloys with such additions. CONFIRMATION COPY The powder used in accordance with the way of production of the invention, is produced by atomization of molten metal by known methods. The powder is put into a metal container which can be shaped in such a way as to produce a part which upon hot isostatic pressing is given a shape which is ready for use. The container material is removed by chemical or mechanical means, for example pickling or turning. Another way to produce a powder metallurgical part of finished shape for hot isostatic pressing is metal injection moulding (MIM), in which process a mixture of metal powder and a binder is shaped into a green body. The green body is sintered and the binder is burnt off. This method is suited for large series of components, while the method described above using metal capsules lends itself more to single part production. It is to be recommended that the surface of the component is preoxidized prior to use. In doing so, a layer of aluminium oxide is formed on the surface. This is also the case under normal operating conditions, when this is done at high temperature and in oxidizing atmosphere. By preoxidation the properties of the layer can be better controlled and more dense layer can be obtained than would otherwise be the case. Also in non-oxidizing atmosphere such a layer has good heat resistance. Products manufactured as described in the invention have unique properties in aggressive enviroments, especially in carbon and sulphur containing atmospheres.

Claims: CLAIMS 1. Method of manufacturing high temperature resistant shaped parts of an iron- chromium-aluminium alloy, comprizing 2-10 weight-% aluminium, 10-40 weight-% chromium, balance basically iron, characterized in that a powder of desired composition is hot isostatically pressed to a predetermined shape, ready for use. 2. Method according to claim 1 characterized in that the manufactured product is pre-oxidized to form a protective layer of aluminium oxide on the surface.

Inventors: FRANZEN ULF, OLSSON JAN OLOV, FRANZEN, ULF, OLSSON, JAN, OLOV
Applicants: FRANZEN ULF, KANTHAL AB, OLSSON JAN OLOV, FRANZEN, ULF, OLSSON, JAN, OLOV
Application year: 1996
Main classification: B22F3
IPC codes: B22F3, C22C33, C23C8