Composition

Heat Resistance

Oxidation- excellent resistance to air, at temperatures up to 1150°C. At high temperatures the steel quickly forms a thin, highly adherent and elastic oxide. This oxide gives good protection even under cyclic conditions.

Carburisation- Under oxidising conditions this grade can perform well, but alloys with higher nickel content are preferred if the atmosphere is reducing.

Sulphidation- good resistance to sulphur-bearing gases in an oxidising atmosphere, even if only traces of oxygen are present. Reducing gases prevent the protective oxide forming.

253MA has high strength at elevated temperatures so is often used for structural and pressure-containing applications at temperatures above about 500°C and up to about 900°C. Its strength at these temperatures is higher than that of alternatives such as Grade 310.

253MA will become sensitised in the temperature range of 425-860°C; this is not a problem for high temperature applications, but will result in reduced aqueous corrosion resistance.

Heat Treatment

Solution Treatment (Annealing) - Heat to 1050-1150°C and cool rapidly. It is recommended that the material be solution treated after 10-20% cold work to achieve maximum creep strength in service.

This grade cannot be hardened by thermal treatment.

Applications

Typical applications include:

· Furnace components including burners, retorts, conveyor belts, fans, jigs and baskets, rollers, walking beams, radiant tubes, electric heater elements, refractory anchors, hoods, flues, grates, expansion bellows.

· Petrochemical and refinery tube hangers.