Sandvik 5R75 – Premium Austenitic Stainless Steel with Titanium Stabilization

Sandvik 5R75 is used for a variety of industrial applications. Typical examples are heat exchangers, condensers, pipelines, cooling and heating coils in the chemical, petrochemical and pulp and paper industries.

Annealing after cold bending is not normally necessary, but this point must be decided with regard to the degree of bending and the operating conditions. Heat treatment, if any, should take the form of stress-relieving or solution-annealing, see under "Heat treatment".

General corrosion: Sandvik 5R75 has good resistance to:

Sandvik 3R12 has better resistance than normal type ASTM TP304 to oxidizing agents, such as nitric acid. The Figure on the right side of the datasheet shows isocorrosion in nitric acid for Sandvik 3R12.

Intergranular corrosion: Sandvik 5R75 has better resistance to intergranular corrosion than unstabilized steels. The addition of titanium prevents precipitation of chromium carbides in the grain boundaries after prolonged heating in the temperature range 450- 850°C (840-1560°F).

Pitting and crevice corrosion: Resistance to these types of corrosion improves with increasing molybdenum content and Sandvik 5R75 with about 2.1% Mo has substantially higher resistance than steels of type AISI 304/304L.

Stress corrosion cracking: Austenitic stainless steels are susceptible to stress corrosion cracking. This may occur at temperatures above about 60°C (140°F), if the steel is subjected to tensile stresses and at the same time comes into contact with certain solutions, particularly those containing chlorides. Such service conditions should therefore be avoided. Conditions when plants are shut down must also be considered as the condensates which are then formed can develop a chloride content that leads to both stress corrosion cracking and pitting.

In applications demanding high resistance to stress corrosion cracking, austenitic- ferritic steels, e.g. Sandvik SAF 2304 or SAF 2205, are recommended. See data sheets S-1871-ENG and S-1874-ENG.

Gas corrosion: Sandvik 5R75 can be used in:

Creep behavior should also be taken into account when using the steel in the creep range. In flue gases containing sulfur, the corrosion resistance is reduced. In such environments these steels can be used at temperatures up to 600-750°C (1110-1380°F) depending on service conditions. Factors to consider are whether the atmosphere is oxidizing or reducing, i.e. the oxygen content, and whether impurities such as sodium and vanadium are present.

The tubes are normally delivered in heat treated condition. If additional heat treatment is needed after further processing the following is recommended.

Stress relieving: 850-950°C (1560-1740°F), 10-15 minutes, cooling in air.

Solution annealing: 1000-1100°C (1830-2010°F), 5-20 minutes, rapid cooling in air or water.

Hot bending is carried out at 1100-850°C (2010-1560°F) and should be followed by solution-annealing.

Sandvik 5R75 has good machining properties. Detailed recommendations for the choice of tools and cutting data are provided in brochures S-0291-ENG and S-1492-ENG.

Forms of supply:

Tube and pipe are normally delivered in the solution-annealed and white-pickled condition. Smaller sizes may be bright-annealed.

Hollow bar is supplied solution-annealed and white-pickled.

The weldability of Sandvik 5R75 is good. Welding must be carried out without preheating and subsequent heat treatment is normally not required. 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 5R75, heat input of <1.5 kJ/mm and interpass temperature of <150°C (300°F) are recommended.

Recommended filler metals:

• TIG/GTAW or MIG/GMAW welding
  • ISO 14343 S 19 12 3 Nb / AWS A5.9 ER318 (e.g. Exaton 19.12.3.Nb )
• MMA/SMAW welding
  • ISO 3581 E 19 12 3 Nb R / AWS A5.4 E318-17