# Hastelloy B (UNS N10001) Alloy Properties and Applications

## Introduction to Hastelloy B (UNS N10001)

Hastelloy B, also known by its UNS designation N10001, is a nickel-molybdenum alloy renowned for its exceptional resistance to hydrochloric acid and other reducing chemicals. Developed by Haynes International, this alloy has become a cornerstone material in industries dealing with highly corrosive environments.

## Chemical Composition

The chemical composition of Hastelloy B plays a crucial role in its performance characteristics:

– Nickel (Ni): 62-70%
– Molybdenum (Mo): 26-30%
– Iron (Fe): 4-6%
– Chromium (Cr): 0.5-1.5%
– Manganese (Mn): ≤1.0%
– Silicon (Si): ≤1.0%
– Carbon (C): ≤0.05%
– Cobalt (Co): ≤2.5%

## Physical Properties

Hastelloy B exhibits several notable physical properties:

– Density: 9.24 g/cm³ (0.334 lb/in³)
– Melting Range: 1330-1380°C (2426-2516°F)
– Electrical Resistivity: 1.37 μΩ·m
– Thermal Conductivity: 10.1 W/m·K (70°F)
– Coefficient of Thermal Expansion: 11.5 μm/m·K (20-100°C)

## Mechanical Properties

The alloy demonstrates impressive mechanical characteristics:

– Tensile Strength: 690 MPa (100 ksi) min
– Yield Strength (0.2% offset): 310 MPa (45 ksi) min
– Elongation: 40% min in 2 inches
– Hardness: Rb 90 max (annealed condition)

## Corrosion Resistance

Hastelloy B’s primary advantage lies in its corrosion resistance:

– Excellent resistance to hydrochloric acid at all concentrations and temperatures
– Good resistance to sulfuric, phosphoric, and acetic acids
– Performs well in reducing environments
– Limited resistance to oxidizing environments
– Susceptible to stress corrosion cracking in chloride environments above 150°C (302°F)

## Applications of Hastelloy B

Due to its unique properties, Hastelloy B finds applications in various industries:

### Chemical Processing

– Reactors and vessels handling hydrochloric acid
– Heat exchangers in corrosive environments
– Piping systems for aggressive chemicals

### Pharmaceutical Industry

– Equipment for drug synthesis
– Storage tanks for corrosive intermediates
– Process piping in pharmaceutical manufacturing

### Other Applications

– Pollution control equipment
– Pickling operations
– Acid production facilities

## Fabrication and Welding

Hastelloy B can be fabricated using standard techniques with some considerations:

– Hot working should be performed between 870-1200°C (1600-2200°F)
– Cold working requires intermediate annealing
– Welding can be performed using Hastelloy B filler metal
– Post-weld heat treatment is recommended for optimal corrosion resistance

## Limitations and Considerations

While Hastelloy B offers excellent performance in many applications, there are some limitations:

– Not suitable for oxidizing environments
– Requires proper heat treatment to avoid intergranular corrosion
– More expensive than standard stainless steels
– Requires specialized welding procedures

## Conclusion

Hastelloy B (UNS N10001) remains a vital material for industries requiring resistance to reducing environments, particularly hydrochloric acid. Its unique combination of properties makes it indispensable in chemical processing, pharmaceuticals, and other applications where conventional materials fail. Proper selection, fabrication, and maintenance are essential to maximize the performance of this high-performance alloy.