Sandvik 4C54

Sandvik 4C54 should be chosen mainly for service at temperatures above 700°C (1290°F) where the excellent resistance of the material to slag corrosion and sulphidizing gases is particularly advantageous. Typical applications for Sandvik 4C54 are:

Since Sandvik 4C54 has very large creep rupture elongation, often more than 100%, and little resistance to creep, it is necessary to allow for considerable creep deformation long before rupture occurs. At normal service temperatures, i.e. over 700 °C (1290 °F), even the dead weight of the tubes can cause stresses leading to large deformations.

Careful attention must be given, therefore to the way in which tubes are supported. Sandvik 4C54, in common with other ferritic chromium steels, is less tough than austenitic stainless steels in the as delivered condition. The transition temperature of Sandvik 4C54 is around 100-150 °C (210-300 °F). After a period of operation, toughness at room temperature can decrease further. For this reason, large impact and similar stresses should be avoided during repairs.

The graph in Fig. 1 can be used to determine the temperature above which, design calculations should be based on creep rupture strength rather than proof strength.

For cold bending, cold worked tubes are recommended. Annealing is usually not necessary after cold bending.

When straightening or bending tubes that have already been in service, we recommend the following:

Air: Sandvik 4C54 is highly resistant to oxidation, both at constant and at cyclically varying temperatures (see Fig. 2). The service temperature in air should not exceed about 1100°C (2010°F).

Isothermal oxidation: at 1100°C (2010°F) for 1000h results in a weight loss of about 0.25 g/m2 h after removal of the oxide layer.

Cyclic oxidation: at 1100°C (2010°F) for 5 x 24 h, with cooling to room temperature every 24 hours, gives a weight loss of less than 1.5 g /m2 h after removal of the oxide layer.

Hot corrosion / sulphidation: Owing to its high chromium content and the absence of nickel, Sandvik 4C54 has very good resistance in sulphidizing gases and salts. The steel has relatively good resistance to slags containing vanadium pentoxide and sodium sulphate, for example, which are extremely aggressive at temperatures above 600°C (1110°F). The results of a corrosion test in combustion gases from heavy oil show that Sandvik 4C54 possesses better resistance than 50Cr50Ni alloy and austenitic high temperature steels in such environments (see Fig. 3).

In other sulphurous flue gases, especially where the oxygen pressure is low (reducing atmosphere), Sandvik 4C54 possesses considerably better resistance than the austenitic steels. In laboratory tests simulating combustion in a fluidized bed, where the oxygen pressure varies between low and high, Sandvik 4C54 exhibits very good resistance. See Fig. 4.

Nitrogen pick up: Nitrogen pick up can occur in gas mixtures with low oxygen concentrations and high concentrations of nitrogen, cracked ammonia or mixtures of nitrogen and hydrogen. It leads to embrittlement and reduced oxidation resistance. Sandvik 4C54 is more sensitive than austenitic steels to environments where nitrogen pick up can occur.

Carburizing atmosphere: When a material comes into contact with hot gases containing hydrocarbons and carbon monoxide, carburization can occur. The extent of carburization depends on the composition of the material and of the gas.

The relatively high chromium content of Sandvik 4C54 promotes the formation of a protective oxide layer on the surface of the material, providing some protection against carburization.

However, because Sandvik 4C54 is ferritic, carburization occurs quickly, if the oxide layer cracks or, if the oxygen content is too low to form a protective oxide layer. For this reason, the material does not possess the same resistance as the austenitic steels, for example, Sandvik 253MA or Sanicro 31HT.

Metal and salt baths: The ferritic structure of Sandvik 4C54 gives it good resistance in baths of molten copper. It also possesses good resistance in other molten metals, such as lead, tin, bearing metals, brass and magnesium. In these metals, it is a good idea to use replaceable sleeves of ceramic material or graphite, since corrosion is heaviest at the surface of the metal bath. In salt baths for heat treatment etc., such as cyanide and neutral salt baths, austenitic alloys with a high nickel content should be selected instead (e.g. Sanicro 31HT).

Tubes are delivered in the heat treated condition. If another heat treatment is needed after further processing, the following is recommended:

Stress relieving: 800-850°C (1470-1560°F), 15-30 minutes, rapid cooling in air.

Solution annealing: 800-900°C (1470-1650°F), 30-60 minutes, rapid cooling in air.

Due to their limitations in ductility at low temperatures, caution must be taken when performing bending of ferritic steels, such as Sandvik 4C54.

Hot worked tubes should preferably be hot bent, but they can be bent cold, depending on bending radius, diameter, bending equipment, etc. Please contact Sandvik for more information.

Hot bending is carried out at 1000-800°C (1830-1470°F) and should be followed by annealing, see the Heat treatment section, for details.

Forms of supply:

Seamless tube and pipe in Sandvik 4C54 is supplied in dimensions up to 125 mm outside diameter in the solution annealed and white pickled condition or in the bright annealed condition.

Stock sizes

Sandvik 4C54 is stocked in sizes ranging from outside diameter 3/8" to 3" outside diameter. Additional data concerning sizes and finishes is available on request from your nearest Sandvik office.

Temperatures of about 400-550°C (750-1020°F) should be avoided for even short periods of time, whether the steel is in service or merely being held at that temperature, since severe embrittlement, known as 475 oC (887oF). embrittlement, can occur. This is noticeable after the tubes have cooled to room temperature. However, the steel can be restored to its original condition by short term heating at a temperature above 600°C (1110°F). Embrittlement can also occur as a result of sigma phase formation after prolonged service at 550-750°C (1020-1380°F).

The weldability of Sandvik 4C54 is good. Welding must be carried out with preheating at 200-300°C (390-570°F), subsequent heat treatment is normally required for matching filler metals. Suitable methods of fusion welding are manual metal-arc welding (MMA/SMAW) and gas-shielded arc welding, with the TIG/GTAW method as first choice.

For Sandvik 4C54, heat-input of <1.5 kJ/mm and interpass temperature of <150°C (300°F) are recommended.

Recommended filler metals

• TIG/GTAW welding
  • ISO 14343 S 29 9 / AWS A5.9 ER312 (e.g. Exaton 29.9)
  • ISO 14343 S 25 20 / AWS A5.9 ER310 (e.g. Exaton 25.20.C)
  • ISO 18274 S Ni 6082 / AWS A5.14 ERNiCr-3 (e.g. Exaton Ni72HP)
• MMA/SMAW welding
  • ISO 3581 E 29 9 R / AWS A5.4 E312-16 (e.g. Exaton 29.9.R)
  • ISO 3581 E 25 20 B / AWS A5.4 E310-16 (e.g. Exaton 25.20.B)
  • ISO 14172 E Ni 6182/ AWS A5.11 ENiCrFe-3 (e.g. Exaton Ni71)

When using the austenitic stainless-steel wire electrode S 25 20/ER310 and the covered electrode E 25 20 B/E310-16, the higher thermal expansion of the austenitic weld metal must be considered.

When using nickel alloy wire electrode S Ni 6082/ERNiCr-3 and covered electrode E Ni 6182/ENiCrFe-3, a lower corrosion resistance of the weld metal in a reducing sulphurous environment than the Sandvik 4C54 must be considered.