About Smiths Advanced

We are a leading stockholder and global supplier of metals and plastics into Aerospace & Space, Chemical, Defence, Medical, MRO, Naval, Nuclear, Oil & Gas and Power industries.

We make high quality materials available in a fast, cost-effective and convenient package and provide a consistent supply path for all our customers.

Finishing Options

Radiometal 4550

Nickel Iron Alloy Bars

Radiometal 4550 finds extensive use in electronics.

Radiometal 4550 is a nickel-iron alloy highly advantageous in sensitive electronic relays that respond to weak currents. The material offers excellent permeability with high saturation flux density.

The alloy is also widely employed in transformers, chokes and motors, especially when silicon-iron products do not meet magnetic performance levels. Although considered a more ‘niche’ product, Radiometal 4550 represents an attractive engineering material in specific application areas, including protection relays, actuators, servo valves, telecommunications, motors and even missile systems.

Heat Treatment

The alloy is supplied in the hard rolled, hard drawn or softened condition and can be milled, stamped, turned or deep drawn. Following fabrication operations, parts require subsequent heat treatment to maximise magnetic properties. Radiometal 4550 should be heated at 1180° C (2155° F) in dry hydrogen for 4 hours and then cooled to 300° C (507° F) over 8 hours.

Radiometal 4550 Datasheet

Stock Availability

We stock Radiometal 4550 in forged bars 6mm to 75mm diameter and 3 metres in length.


The material work hardens readily, so it is important to choose the right tool geometry, material feeds, speeds, and cutting fluids. Nevertheless, machining nickel-iron alloys is straightforward with high-speed steel or tungsten carbide tooling. Keeping machining blades sharp and speeds low will prevent deceleration by providing enough torque at the cutting edge. Cutting Radiometal 4550 generates significant heat, so coolant is recommended.

Product Features:

    Radiometal 4550

    Electronic relays
    Servo valves and actuators
    Specialist motors

    Excellent magnetic permeability
    High saturation flux density
    Improved magnetic performance compared tosilicon-iron alloys
    Straightforward to machine

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