Characteristic of Super Duplex Seamless Stainless Steel Tubing:

1. Good to very good resistance to uniform corrosion

2. Good to very good resistance to pitting and crevice corrosion

3. High resistance to stress corrosion cracking and corrosion fatigue

4. High mechanical strength

5. Good abrasion and erosion resistance

6. Good fatigue resistance

7. High energy absorption

8. Low thermal expansion

9. Good weldability

Chemical Properties:

Typical values (Weight %)

Mechanical Properties:

Corrosion Resistance:

Super Duplex Seamless Stainless Steel Tubing are extremely corrosion resistant. They have high resistance to intergranular corrosion. Even in chloride and sulphide environments, duplex stainless steels exhibit very high resistance to stress corrosion cracking.

The super duplex grades are even more resistant to corrosion.

Heat Resistance:

The high chromium content of duplex and super duplex seamless stainless steel tubing that protects against corrosion, causes embrittlement at temperatures over about 300°C.

At low temperatures duplex stainless steels have better ductility than the ferritic and martensitic grades. Duplex grades can readily be used down to at least -50°C.

Machinability:

Although machinable, the high strengths of duplex stainless steels makes machining difficult. As an example, machining of 2205 is around 20% slower than for 304.

Machining can be enhanced by using the following rules:

Cutting edges must be kept sharp. Dull edges cause excess work hardening.

Cuts should be light but deep enough to prevent work hardening by riding on the surface of the material.

Chip breakers should be employed to assist in ensuring swarf remains clear of the work

Low thermal conductivity of austenitic alloys results in heat concentratin