Sanicro 30 (Tube and pipe, seamless)

Chemical composition (nominal) %

The Co content is normally max 0.10%. Subject to agreement, material with a lower Co content can be supplied.

Forms of supply-finishes and dimensions

Seamless tube and pipe
Tube and pipe are supplied hot- or cold-worked, solution-annealed and white-pickled or bright-annealed. The principal size range can be seen from Fig. 1, but also certain sizes can be delivered on request.

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

Mechanical properties

The figures below refer to cold-worked and annealed sizes up to 10 mm (3/8") wall thickness. For larger sizes and other finishes values are given on request.
For heat exchangers tubes, higher yield strength according to ASME Code Case N 20 can be applied. Slightly cold worked condition refers to outside diameter below 30 mm (1.2")

At 20°C (68°F)

Annealed condition

1 MPa = 1 N/mm²

Slightly cold-worked condition (O.D. max. 0 mm; 1.2")

At higher temperatures

Annealed condition

Slightly cold-worked condition

Physical properties

Density: 8.0 g/cm3; 0.29 lb/in³
Scaling temperature in air: 1150°C, 2100°F

1) Mean values

1) Mean values (x10^-6)

1) (x10³)

Corrosion resistance

General corrosion

Sanicro 30 has approximately the same resistance to organic and inorganic acids as steel of the ASTM TP 304 type. Its resistance to sodium hydroxide is very good except at the very highest concentrations and temperatures.

Pitting

The material has somewhat better resistance to pitting than steel of the ASTM TP 304 type.

Intergranular corrosion and stress corrosion cracking

In comparison with the standard Alloy 800, Sanicro 30 has improved resistance both to intergranular corrosion and to intergranular stress corrosion cracking. This is obtained by a high degree of stabilisation and a production sequence giving a small grain size. The resistance to transgranular stress corrosion cracking is very good as for all high-nickel alloys.

Gas corrosion

In general this grade is not used at temperatures high enough for gas corrosion to be a problem. For such cases the appropriate metal to choose is Sanicro 31HT. However, compared with Sanicro 31HT, Sanicro 30 has about the same resistance to gas corrosion.

Heat treatment

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

Stress relieving
800-875°C (1470-1605°F), 10-15 minutes, cooling in air

Solution annealing
950-1050°C (1740-1920°F), 1-10 minutes, rapid cooling in water or air.

Welding

The weldability of Sanicro 30 is good. Suitable fusion-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 normally not necessary.

The welding of nickel-base materials calls for special cleanliness. Joint surface and filler metals have to be free from grease, dirt, chalk and other impurities. If necessary, the welding zone should be cleaned with a suitable solvent, e.g. acetone.

Since the material has 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 structure be stress-relieved.

The welding of fully austenitic steels often entails the risk of hot-cracking in the weld metal, particularly if the weldment is under constraint. To reduce the cracking risk, the welding should be carried out with a low heat input.

As filler metal for gas-shielded arc welding we recommend wire of Sanicro 72. In manual metal-arc welding we recommend covered electrodes Sanicro 71. These filler metals has a higher nickel content than parent metal.

Bending

Heat treatment 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.
Hot bending is carried out at 1050-850°C (1920-1560°F) and should be followed by solution annealing.