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Iron & Steel
MPP produces components from a wide variety of powder metal iron and steel alloys, which are generally known as ferrous powder metal alloys. These include admixed elemental ferrous alloys, diffusion alloyed steels, prealloyed low alloy steels, stainless steels, and tool steels. Admixed, Elemental Ferrous Alloys - Pure Fe can be used for soft magnetic and low strength structural applications.
- When Fe is admixed with C, Cu, Ni, P, or Si, and processed by powder metallurgy, the result is carbon, copper, nickel, phosphorus, or silicon steels.
- These steels are used for structural and/or soft magnetic applications.
- Powder metallurgy permits processing of alloys with chemistries that are very difficult to process by other metalworking technologies.
- MPIF STD 35 material designations are F, FC, FN, FY, and FS.
Diffusion Alloyed Steels - Pure Fe is typically partially pre-alloyed ("diffusion alloyed") with Ni, Cu, and Mo.
- Graphite (C) is subsequently admixed with the resulting diffusion alloyed steel powder to produce the required C level in the final product. Also, other elemental powder may be admixed at this stage.
- Diffusion alloyed steels offer the benefits of a soft Fe core, for compressibility, together with alloying elements that are partially sintered/diffused into the core.
- Diffusion alloyed steels are typically used in medium to high strength structural applications.
- Strength and wear resistance can be further enhanced by heat treating these steels.
- MPIF STD 35 material designation is FD.
Prealloyed Low Alloy Steels - Typically, Fe is fully alloyed with Ni, Mo, Cu and/or Mn. Each powder particle has the same alloy chemistry.
- Graphite (C) is subsequently admixed with the prealloyed powder. Other elemental powders may also be added at this stage.
- Normally only low alloy steels are produced, as otherwise the powder compressibility becomes so low as to be impractical.
- Prealloyed low alloy steels are used in high strength structural applications.
- Strength and wear resistance can be further enhanced by heat treatment.
- Some of these steels can be sinter-hardened.
- MPIF STD 35 material designations are FL, FLN, FLN2, FLN4, FLN6 and FLNC.
Stainless Steels Prealloyed Stainless Steels - Special ferrous-based corrosion-resistant alloys made from prealloyed powders.
- The specific processing parameters used affect the properties of the final product.
- For best corrosion resistance, sinter in vacuum or pure hydrogen at high temperature (>1250°C).
- 300 Series alloys offer the best corrosion resistance.
- Austenitic microstructure (e.g. 303, 304, 309, 316)
- Non-magnetic, so can be used for shielding purposes
- Solid solution strengthening with N will increase mechanical properties, with some loss of corrosion resistance
- 400 Series for moderate corrosion resistance.
- Ferritic microstructure (e.g. 410, 430, 436), but can be processed to create martensitic transformations
- Low levels of C or N can induce solid solution strengthening and the formation of martensite, at the expense of corrosion resistance
- Magnetic, so can be used in solenoid and ABS applications
- Can be heat treated for high strength and hardness
- 409Cb is used for exhaust system components because Cb enhances cyclic oxidation resistance
Tool Steels - Special ferrous-based alloys made from prealloyed powders
- Near net-shape, approaching full density, using liquid phase sintering
- Hardness values greater than HRC 55
- Transverse rupture strengths greater than 200,000 psi
- Highly recommended for compressively loaded wear applications, offering excellent wear resistance
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