A Beginning Toward Understanding the Corrosion Resistance of Ferritic Stainless Steels 930450
To date the market for P/M stainless steel has not developed appreciably, and has centered largely on the development of austenitic 300 series stainless steels. Although these stainless steels are noted for their resistance to corrosion in many media, it has been difficult for P/M parts fabricators to produce parts that will sustain 1,000 hours of protection in a 5% salt solution. The problem starts with the water atomized powders and continues with the sintering practice exercised to produce the parts. Reasons for lack of corrosion resistance, based upon these considerations, will be discussed.
In addition, the ferritic stainless steels are being considered seriously for fuel injectors. These emerging applications derive from the corrosive environment that may become a problem if and when alternative fuels are introduced. P/M ferritic stainless steels may also assume a position as a corrosion resistant magnetic material required in ABS systems which are currently emerging. A highly corrosive environment may again render the ferritic stainless steels practical for these applications.
Magnetic properties of P/M ferritic stainless steels which match those of wrought stainless steel products have been developed. The problem then becomes one of the corrosion resistance of these materials.
This paper will demonstrate the magnetic properties that can be achieved from controlled sintering practice. It will then describe the corrosion resistance that can be expected of these materials today. Finally, the paper will attempt to explore means in which the corrosion resistance of these materials can be improved.