Sandvik 5R75 (Tube and pipe, seamless)

Chemical composition (nominal) %

Forms of supply

Seamless tube and pipe

Tube and pipe are normally delivered in the solution-annealed and white-pickled condition. Smaller sizes may be bright-annealed. The size range can be seen from the principal size range can be seen from Fig. 1.

Figure 1. Principal size range for seamless tube and pipe.

Hollow bar

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

Mechanical properties

At 20°C (68°F)

1 MPa = 1 N/mm²
a) R_p0.2 and R_p1.0 correspond to 0.2% offset and 1.0% offset yield strength, respectively.
b) Based on L₀ = 5.65 √S₀ where L₀ is the original gauge length and S₀ the original cross-section area.
c) For hotfinished tube and pipe with wall thickness greater than 10 mm (0.4 in.) the minimum values for proof strength may fall short of the stated values by 20 MPa (2.9 ksi) and the range for the tensile strength is 490-690 MPa.
d) NFA 49-117 with min 45% can be fulfilled.

Impact strength

Due to its austenitic microstructure, Sandvik 5R75 has very good impact strength both at room temperature and at cryogenic temperatures.

Tests have demonstrated that the steel fulfils the requirements (60 J (44 ft-lb) at -196 ^oC (-320 ^oF)) according to the European standards prEN 13445-2 (UFPV-2) and prEN 10216-5.

At high temperatures

d) For hotfinished tube and pipe with wall thicknesses greater than 10 mm (0.4 in.) the proof strength values may be slightly lower but still fulfill the requirements according to DIN 17458 and SS 14 23 50.

Physical properties

Density: 8.0 g/cm³, 0.29 lb/in³

1) Mean values in temperature ranges (x10^-6)

1) (x10³)

Corrosion resistance

General corrosion

Sandvik 5R75 has good resistance to

Intergranular corrosion

Sandvik 5R75 has better resistance to intergranular corrosion than unstabilised 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 behaviour should also be taken into account when using the steel in the creep range. In flue gases containing sulphur, 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 oxidising or reducing, i.e. the oxygen content, and whether impurities such as sodium and vanadium are present.

Heat treatment

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.

Machining

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.

Welding

The weldability of Sandvik 5R75 is good. Suitable welding methods are manual metal-arc welding with covered electrodes and gas-shielded arc welding with the TIG and MIG methods as first choice. Preheating and post-weld heat treatment are not normally necessary.

Owing to low thermal conductivity and high thermal expansion, welding must be carried out with a low heat input and with welding plans well thought out in advance so that the deformation of the welded joint can be kept under control. If, despite these precautions, it is foreseen that the residual stresses might impair the function of the weldment, we recommend that the entire structure be stress relieved. See under "Heat treatment".

As filler material for gas-shielded arc welding we recommend wire electrodes and rods Sandvik 19.12.3.NbSi, 19.12.3.LSi, 19.12.3.Nb or 19.12.3.L. In manual metal-arc welding the covered electrode Sandvik 19.12.3.LR is recommended.

Bending

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".

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

Applications

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.