Sandvik Ab

Sandvik Intellectual Property Ab

Urban Forsberg

Guocai Chai

Johan Lind&eacute;n

Jan Högberg

Sofia Åkesson

Anders Wilson

An austenitic alloy comprising (in weight %):

Austenitic alloy

A compound tube including a layer of a Fe&mdash;Cr alloy and a layer of load-carrying component, with the optional addition of further layers. The Fe&mdash;Cr alloy preferably has a composition including, in weight-%: less than 0.3% carbon, 15-60% chromium, less than 10% nickel, less than 5% molybdenum, less than 5% silicon, less than 0.3% nitrogen, less than 5% manganese, and the remainder iron with naturally occurring impurities. The compound tubes are very resistant to carbonization and metal dusting, and are suited for use as bayonet tubing, superheater tubing, and reforming tubing in steam formation environments.

Ferritic alloy for constructions

A compound tube comprises a layer of a Fe&mdash;Cr&mdash;Al-alloy and a layer of a load-carrying component and optionally one or several additional layers. The Fe&mdash;Cr&mdash;Al-alloy has the following analysis in weight-%: carbon<0.3, chromium 5-30, nickel<10, manganese<5, molybdenum<5, aluminium 3-20 , silicon<5, nitrogen<0.3, cerium&plus;bafnium&plus;yttrium<1.0, titanium 0.005-1.0, zirconium 0.005-1.0, niobium 0.005-1.0, the remainder iron, and naturally occurring impurities. These tubes are very resistant towards carbonization and &ldquo;metal dusting&rdquo; and are being used to advantage for bayonet tubing, superheat tubing and reformer tubing in steam formation.

Steel alloy for compound tubes

As tube material in waste incineration it has been found advantageous to use a composite tube wherein an inner tube component of a carbon steel or a low-alloy Cr&mdash;Mo-steel is metallurgically bonded to an outer tube component of Ni&mdash;Cr&mdash;Mo&mdash;Nb&mdash;Fe-alloy with an austenitic structure. The composite tube is fabricated by spraying finely distributed metal drops of the outer component onto the inner component in melt condition. After solidifying, the composite tube is then fabricated by joint extrusion.

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Sandviken, Sweden

Urban Forsberg