Chemical composition (nominal) %

Simplified chemical composition for external use:

Alloying elements of more than 1%. Approximate values.

Size range and tolerances

In exceptional cases, spools or coils of lower weight than given in the above tables can be included in a delivery.

Tolerances

The diameter tolerance is normally D2. The wire can also be supplied with tolerance grade D1 and D3.

Forms of supply

The material is delivered in lots and forms adapted to the customer's requirements:

• in coils with weights up to 150 kgs
• on various types of spools with wire weights up to 1 000 kgs
• in straightened lengths up to 4 m

Physical properties

Density, g/cm³ (lb/in³): 7.9 (0.29)

1) For material in aged condition

1) For material in aged condition

Thermal expansion

Mean values in temperature ranges (x10^-6)

The material has a coefficient of thermal expansion close to that of carbon steel. This gives it definite design advantages over normal austenitic stainless steels. The values given in the table are average values in the temperature ranges.

1) x10^-6/^oC

1) x10^-6/^oF

Modulus of elasticity

The E-modulus is dependant on dimension, condition, direction and amount of cold reduction of the material. The data below have been achieved by tensile testing at 20^oC (68^oF) of cold rolled strips along the rolling direction and they are typical values only. At ageing an increase of the E-modulus with 15 - 20 x10³ MPa can be expected.

Mechanical properties

The possible ranges for the mechanical properties both in cold rolled and aged condition are indicated below.

The strength level after ageing depends on the amount of cold deformation and therefore also on the dimension.

For more information regarding ageing, click here.

1 MPa = 1 N/mm²
a) R_p0.2 correspond to 0.2% offset yield strength.

At elevated temperatures

The values represents testing on material cold worked to 1650 MPa and subsequently aged at 475°C for 4 hours.

Corrosion resistance

The material has a corrosion resistance comparable to AISI 304L or AISI 316L depending on condition and environment.

Pitting and crevice corrosion

The Critical Pitting crrosion Temperature, CPT, has been decided using Electrochemical CPT testing at 300 mV in NaCl solutions of different concentrations at pH = 6.0, ground test samples (600 mm). Al results are average values from six measurements.

Pitting corrosion

Figure 1: Critical pitting temperatures (CPT) for Sandvik Nanoflex, AISI 304 and AISI 316 at varying concentrations of sodium chloride. Pontiostatic determinations at +300 mV (SCE), pH= 6.0

Figure 2: Isocorrosion diagram for Sandvik Nanoflex, AISI 304L and 316L in stagnant sulphuric acid. The curves for AISI 304L and 316L and the dot for Sandvik Nanoflex represents a corrosion rate of 0.1 mm/year.

Heat treatment

The material was developed for applications requiring ultra-high strength in combination with good fracture toughness. The strength is increased remarkably at a heat treatment in the temperature range of 400 - 450^oC (750- 840^oF), whereby precipitation occurs in the martensitic matrix. This heat treatment is called ageing or tempering and it is preferably made on the final product, to first take advantage of the good formability in as delivered condition.

The optimum ageing is made at 475^oC (885^oF) for 4 hours. Some examples of the ageing effect on the tensile strength is given below.

Weldability

The weldability is good. Suitable welding methods are TIG, MIG and MMA. It can be welded without filler metal (autogenously) using the TIG process, but filler metal is preferable. For TIG and MIG welding, Sandvik 19.12.3.LSi or 19.12.3.L can be used, or if a higher strength is desired, Sandvik 22.8.3.L.

For MMA, the corresponding electrodes Sandvik 19.12.3.LR or Sandvik 22.9.3.LR are suitable.

The martensitic content in HAZ of the material, decreases after welding resulting in a typical annealed microstructure with an austenitic matrix and a small amount of ferrite. This means that the tensile strength will be lower for the weld compared with the high strength base material. Therefore, welds in the material are not suitable for active parts of a construction, when extremely high strength is required.