ASTM ASME SB 649 Alloy 31 UNS N08031 Bar

ASTM ASME SB 649 Alloy 31, also known as UNS N08031, is a high-performance nickel-chromium-molybdenum-iron alloy with nitrogen and copper additions. It offers exceptional corrosion resistance in highly corrosive environments, including those containing sulfuric acid, hydrochloric acid, phosphoric acid, and seawater. When supplied in the form of bars, Alloy 31 can be utilized in various applications where corrosion resistance and high strength are crucial. Here are some details about Alloy 31 bars:

Grade Name:

DIN: X1NiCrMoCu32-28-7

JIS: -

EN: 1.4562

ASME: SB 649, UNS N08031

Elemental Composition:

Nickel (Ni): 30.0-32.0%

Chromium (Cr): 26.0-28.0%

Molybdenum (Mo): 6.0-7.0%

Iron (Fe): Balance

Nitrogen (N): 0.15-0.25%

Copper (Cu): 1.0-1.4%

Manganese (Mn): 2.0% max

Silicon (Si): 0.3-0.8%

Carbon (C): 0.015% max

Sulfur (S): 0.01% max

Phosphorus (P): 0.04% max

Mechanical Properties:

Tensile Strength: 100 ksi (minimum)

Yield Strength (0.2% offset): 45 ksi (minimum)

Elongation: 40% (minimum)

Hardness: Typically around 190 HB (Brinell hardness)

Application Range:

Chemical processing: Equipment for handling sulfuric acid, phosphoric acid, hydrochloric acid, and other aggressive chemicals.

Petrochemical industry: Components in reactors, heat exchangers, and piping systems exposed to corrosive environments.

Marine industry: Components for seawater desalination plants, offshore platforms, and shipbuilding.

Power generation: Heat exchangers, condensers, and boiler components.

Pharmaceutical industry: Equipment for manufacturing pharmaceuticals and chemicals.

Manufacturing Process:

Alloy 31 bars are typically manufactured through processes such as hot rolling, cold drawing, or hot forging. Heat treatment may be applied to achieve desired properties.

Quality Control:

Material testing for chemical composition and mechanical properties.

Non-destructive testing (e.g., ultrasonic testing, radiographic testing).

Dimensional inspection.

Surface inspection.

Pressure testing (if applicable).

Other Common Types:

Alloy 31 is primarily supplied in the form of bars, but it's also available in other forms such as sheets, plates, pipes, tubes, fittings, and welding wire.

Common Q&A:

Q: Can Alloy 31 withstand high concentrations of sulfuric acid?

A: Yes, Alloy 31 offers excellent resistance to sulfuric acid, even at high concentrations and elevated temperatures.

Q: Is Alloy 31 weldable?

A: Yes, Alloy 31 is weldable using conventional welding techniques. It's recommended to use matching composition filler metals to ensure the integrity of the weld joint.

Q: What are the temperature limitations of Alloy 31?

A: Alloy 31 can be used at temperatures up to around 450°C (842°F) in oxidizing environments and up to around 600°C (1112°F) in reducing environments.

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