Chrome Core® 18-FM Solenoid Quality Stainless
Type Analysis
Single figures are nominal except where noted.
Carbon 0.02 % Manganese 0.40 %
Phosphorus 0.020 % Sulfur 0.300 %
Silicon 0.90 % Chromium 17.50 %
Nickel 0.20 % Molybdenum 1.75 %
Columbium/Niobium 0.25 % Iron Balance
General Information
Description
Carpenter Chrome Core® 18-FM Solenoid Quality stainless is a soft magnetic ferritic material designed for operation in more corrosive environments than tolerated by 18% Cr-Fe Type 430 stainless. This new material has corrosion resistance superior to that of Type 430FR Solenoid Quality stainless with generally similar magnetic properties.
Chrome Core 18-FM Solenoid Quality stainless is stabilized with columbium to provide improved corrosion resistance with optimum machinability. The alloy balance also provides resistivity similar to that of Type 430FR Solenoid Quality stainless. High resistivity is beneficial in applications involving AC excitation due to the suppression of eddy current losses.
Chrome Core 18-FM Solenoid Quality stainless is available in the magnetically soft condition, requiring only machining for production of solenoid parts. This alloy may be used as machined if tooling and coolants are not laden with free iron from machining carbon steel. Users who perform their own heat treatment may purchase material which has not been treated at Carpenter.
Corrosion Resistance
Chrome Core 18-FM Solenoid Quality stainless provides the highest level of corrosion resistance of the Carpenter solenoid quality materials. It has resistance superior to that of Type 430FR Solenoid Quality stainless and is a candidate for service in corrosive aqueous environments and mild chemicals.
The improvement over Type 430FR Solenoid Quality stainless was demonstrated by critical crevice corrosion tests in 5% FeCl3 + 1% NaN03. Crevice specimens were exposed for 24 hours at successively higher temperatures until crevice attack was noted. Type 430FR Solenoid Quality stainless was attacked at 41°F (5°C), while Chrome Core 18-FM Solenoid Quality stainless typically withstood attack up to 77°F (25°C). This test was designed to demonstrate material differences and was more severe than many service environments.
