Nickel Aluminium Bronze (NAB) Investment Castings: The Preferred Choice for Critical Applications

Nickel Aluminium Bronze alloys

In the realm of precision-engineered components, Aluminium Bronze and Nickel Aluminium Bronze (NAB) alloys are distinguished by their unique combination of mechanical strength, corrosion resistance, wear resistance, and non-sparking properties.

These copper-based alloys have become the preferred choice across high-demand industries such as marine, offshore oil and gas, petrochemicals, aerospace, defense, and energy. Their ability to perform reliably in extreme environments, coupled with their excellent suitability for the Lost Wax Casting or Investment Casting process, makes Aluminium Bronze castings a compelling solution for high-specification applications.

Pahwa MetalTech, a trusted manufacturer of castings in high-performance non-ferrous alloys, specializes in producing Aluminium Bronze Investment Castings tailored to the stringent requirements of our global clientele.

In this article we will cover the following points:

1. Understanding Aluminium Bronze alloys

2. Lost Wax Casting and Melting of Aluminium Bronze

3. Advantages and Applications Aluminium Bronze alloys

4. Other Bronze Alloys

Understanding Aluminium Bronze Alloys

Aluminium Bronze refers to a group of copper-based alloys typically containing 5% to 14% Aluminium, along with elements such as iron, nickel, manganese, or silicon that enhance both mechanical strength and corrosion resistance. The addition of Aluminium leads to the formation of a robust oxide film, offering excellent resistance to oxidation, erosion, and chloride-induced corrosion.

These alloys exhibit exceptional mechanical properties, including tensile strengths that often exceed those of mild steel, along with excellent fatigue resistance, creep resistance, and suitability for both static and dynamic loading conditions.

Nickel Aluminium Bronze (NAB)

Nickel Aluminium Bronze (NAB), exemplified by alloys such as C95500 and C95800, is a high-strength variant of Aluminium bronze. It typically comprises 8.5–11% aluminum, 4–5% nickel, 3–5% iron, and trace amounts of manganese. The interaction of these elements enhances the alloy's microstructure, making NAB highly resistant to:

1. Seawater corrosion and biofouling

2. Cavitation erosion in pumps and propellers

3. Stress corrosion cracking

4. Magnetism, due to its low magnetic permeability, ideal for defense and naval systems

This alloy is particularly well-suited for marine applications (e.g., propellers, pump housings), offshore platforms, chemical processing, and power generation systems.

Lost Wax Casting and Melting of Aluminium Bronze

Aluminium Bronze offers good castability due to its short freezing range, which ensures uniform material properties across varied section thicknesses.

However, special care is required during melting and pouring to avoid oxide inclusions. Controlled cooling rates and adequate feeding systems are essential during solidification to prevent Aluminium oxide dross from being entrapped within the casting. Experienced foundries like Pahwa MetalTech have the technical expertise and infrastructure to consistently manufacture and achieve high-integrity, defect-free Bronze castings.

A key advantage of Aluminium Bronze is its compact solidification—similar to that of pure metals—which makes the metal inherently sound, especially when compared to alternatives like gunmetal (Tin Bronze, UNS C90500), which may become porous if not rapidly cooled.

Heat treatment can further enhance the wear resistance of Aluminium Bronze castings. To relieve stress introduced during machining or welding, components can undergo annealing and homogenization cycles, which we perform in-house.

Aluminium Bronze castings can be produced via multiple methods including sand, shell, permanent mold (low-pressure die), ceramic, investment, centrifugal, and continuous casting. Component sizes may range from small investment castings to propellers weighing up to 150 kg. The Investment Casting process offers significant advantages, especially when manufacturing complex geometries such as toroidal propellers in Bronze and Stainless Steel alloys.

Advantages and Applications of Nickel Aluminium Bronze alloys

1. Exceptional Strength and Durability

   
   

   Aluminium Bronze Investment Castings offer as-cast tensile strengths in the range of 500–590 MPa, which can be further increased through heat treatment. This places them on par with certain steels while retaining copper alloys’ inherent corrosion resistance and machinability. Ideal applications include:

   1. Bearings and bushings

   2. Propellers and wear plates

   3. Pump impellers and valve bodies

These castings maintain mechanical integrity at elevated temperatures and exhibit superior fatigue resistance during prolonged use.

2. Outstanding Corrosion and Cavitation Resistance

   
   

   The formation of an Aluminium oxide film makes the alloy extremely resistant to corrosion in chloride-rich environments such as seawater and aggressive chemicals. NAB alloys, in particular, withstand:

   1. Pitting and crevice corrosion

   2. Galvanic corrosion when in contact with dissimilar metals

   3. Erosion from high-velocity fluid streams

These features are critical for use in marine systems, desalination plants, and chemical processing equipment.

3. Ideal for Non-Sparking and Hazardous Environments

   

   Aluminium Bronze is non-sparking, making it ideal for environments involving flammable gases, vapors, or dust. Explore Pahwa MetalTech’s BronAL range of Nickel Aluminium Bronze Non-Sparking tools and components. Key applications include:

   1. Mining and tunneling operations

   2. Oil and gas refineries

   3. Chemical plants and explosive-handling zones

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Non-sparking cast components from NAB help prevent ignition sources, enhancing workplace safety.

4. High-Quality Surface Finish and Dimensional Accuracy

   
   

   The Lost Wax Casting process allows Aluminium Bronze to achieve:

   1. Complex, intricate geometries

   2. Superior surface finish with minimal post-processing

   3. Tight dimensional tolerances (CT6–CT7 as per ISO 8062)

Its short freezing range results in uniform solidification, which minimizes porosity and ensures consistent mechanical properties.

5. Superior Performance in Extreme Conditions

   
   

   Aluminium Bronze maintains structural stability in cryogenic conditions and high-pressure environments, making it suitable for:

   1. Valves handling liquified gases

   2. Aerospace components exposed to thermal cycling

   3. Turbines and heat exchangers in power generation

Other Bronze Alloys We Work With

While Aluminium Bronze is ideal for demanding applications, Pahwa MetalTech also specializes in other Bronze Investment Casting alloys, including:

1. Silicon Bronze (C87300, C87500)

   
   

   Silicon Bronze offers moderate strength and excellent corrosion resistance in chemical and water environments. Ideal for:

   1. Bearings and gears

   2. Plumbing fixtures

   3. Pump and valve components with complex shapes

2. Manganese Bronze (C86200, C86300, C86500)

   
   

   Manganese Bronze is renowned for its high tensile strength and wear resistance. Suitable for:

   1. Gear blanks

   2. Hydraulic cylinder parts

   3. Winches and hoisting mechanisms

   
   

   These alloys provide cost-effective solutions for heavy-duty industrial applications.

3. Tin Bronze (C90300, C90500, C90700)

   
   

   Tin Bronzes offer excellent load-bearing capability, shock resistance, and low friction, making them suitable for:

   1. Bearings and bushings

   2. Bridge bearings

   3. Valve guides and seats

   
   

   They are also favored in musical instrument components due to their specific acoustic frequencies. We have successfully manufactured Tin Bronze castings with wall thicknesses as low as 0.8 mm using vacuum investment casting.

Why Pahwa MetalTech is Your Ideal Casting Partner

As a leading manufacturer of Non-Ferrous Lost Wax Castings in India, Pahwa MetalTech offers:·

1. Custom alloy development (AB1, AB2, C95400, C95500, C95800, etc.)

2. Use of High Quality Input raw materials leads to higher quality of finished castings.

3. Air and Vacuum Lox Wax Casting for Non-Ferrous alloys

4. In-house Simulation Expertise thereby optimized Gating and feeding leads to no casting defects

5. In-house heat treatment capabilities

6. Part weights ranging from a few grams to over 80 kg

Contact Us for High-Performance NAB Castings

When your components require durability, reliability, and superior performance, Aluminium Bronze is the optimal material. At Pahwa MetalTech, we combine our metallurgical expertise with advanced casting technology to deliver high-performance Investment Castings of Aluminium Bronze and other copper (Brass and Bronze) alloys.

Email us at info@pahwametaltech.co.in. Visit our Investment Casting Page to explore our complete Lost Wax Casting and alloy capabilities.

Let’s engineer excellence—together.

Keywords: Aluminium Bronze, Nickel Aluminium Bronze, Lost Wax Casting, Investment Castings, Manufacturer of Castings