Incoloy 028 (UNS N08028) Pipe Manufacturing Process

Incoloy 028 (UNS N08028) Pipe Manufacturing Process

UNS N08028 Nickel-Based Alloy Oil Casing Pipe Manufacturing Process: Pipe preparation → Ring furnace heating → Primary frequency heating → Hole expansion → Secondary frequency heating → Hot extrusion → (Straightening) → Pickling, inspection, and grinding → End finishing → Ashing → Drawing (second pass) → (Straightening) → Pickling, inspection, and grinding → End finishing → Cold rolling → Solution treatment → Straightening → Pickling, inspection, and grinding → Cold rolling → Pickling → Non-destructive testing (hydraulic pressure, ultrasonic) → Finished product inspection → Warehousing.
Incoloy 028 (UNSN08028, W.Nr. 1.4563)

I. Standard Number: ASTM B668-05

II. Chemical Composition (wt%):

C: ≤0.03

Cr: 26.0~28.0

Ni: 30.0~34.0

Mo: 3.0~4.0

Fe: Balance

Si: ≤1.0

Mn: ≤2.5

P: ≤0.03

S: ≤0.03

Cu: 0.6~1.4

III. Physical Properties:

Density: 8.0 g/cm³

IV. Corrosion Properties:

Incoloy 028 is a nickel-iron-chromium alloy with added molybdenum and copper. It exhibits excellent resistance to reducing or oxidizing acids, stress corrosion cracking, and corrosion caused by the service environment, such as pitting and crevice corrosion. This alloy is particularly resistant to sulfuric acid and phosphoric acid corrosion. Used in chemical processing, pollution control equipment, pipelines for oil and gas wells, nuclear fuel reprocessing, and acid production and pickling equipment. V. Mechanical Properties:

Tensile Strength (annealed) (MPa): 500

Yield Strength (annealed) (MPa): 214

Elongation at Break (cold working) %: 15

Elastic Modulus (GPa): 200

Rockwell B Hardness Tester: 80-90

Rockwell C Hardness Tester: 33

I. Composition of Nickel Alloys

Nickel alloys are special alloy materials whose main component is nickel. Besides nickel, they also contain other elements such as cobalt, iron, chromium, tungsten, molybdenum, and copper. The addition of these elements improves the physicochemical properties of nickel alloys, especially enhancing their corrosion resistance.

II. Crystal Structure of Nickel Alloys

The crystal structure of nickel alloys is also one of the important reasons for their corrosion resistance. Nickel alloys have a face-centered cubic crystal structure, which enables them to resist corrosion at room temperature. Furthermore, at high temperatures, the crystal structure of nickel alloys remains stable, preventing phase transformation and grain boundary corrosion, thus further enhancing their corrosion resistance.

III. Corrosion Resistance Mechanisms of Nickel Alloys

The corrosion resistance mechanisms of nickel alloys mainly include the following aspects:

1. Passivation: Elements added to nickel alloys can form an oxide layer and a stable passivation film on the surface, thereby preventing further corrosion. For example, molybdenum can form a passivation film at high temperatures, exhibiting significant corrosion resistance.

2. Localized Corrosion Inhibition: Elements in nickel alloys can inhibit the occurrence of localized corrosion and slow down the progression of corrosion. For example, chromium and molybdenum can react with oxygen to form CrO3 and MoO3, respectively. These compounds can cover the metal surface, forming a stable protective film.

3. Intermetallic Effect: Different metals exhibit intermetallic effects, where some metals can prevent the corrosion of other metals. For example, chromium and molybdenum can prevent the corrosion of nickel; therefore, nickel alloys with these elements added have strong corrosion resistance.

4. Improvement of Microstructure and Lattice Structure: Elements added to nickel alloys can improve their microstructure and lattice structure, thereby enhancing their strength and corrosion resistance. For example, the addition of iron to nickel alloys can form the γ’ phase, significantly increasing their strength and hardness.

In summary, nickel alloys possess excellent corrosion resistance and are a very important special alloy material. This is due to the combined effect of their composition, lattice structure, and corrosion resistance mechanism.