Powder Metallurgy Material Guide

If you are considering powder metallurgy (PM) for a component previously produced via a different manufacturing method, one key item for consideration is choice of material.  Many customers come to Porite with a material specified on their part print that comes from either American Iron and Steel Institute (AISI) or Japanese Industrial Standards (JIS).  However, to form a component from powder metal, an appropriate metal powder material must be selected.  These materials are classified by the Metal Powder Industries Federation (MPIF).

To help aid your material selection, Porite has put together the chart of comparable materials below.

The PM equivalent is chosen based on its chemical composition and its ability to maintain similar strength; however, producing a component with metal powder will inevitably result in different characteristics than standard metal.

Below is an example of some differences that you might see in comparable materials.

Although materials with identical chemical compositions are theoretically possible, in powder metallurgy, achieving an exact match with bulk materials can be challenging due to the following:

• Powders are prone to surface oxidation; as a result, carbon (C) and oxygen (O) levels may fluctuate during sintering, leading to slight variations in chemical composition.
• Since full density is not achieved after pressing and sintering (porosity) the mechanical properties can differ significantly.

Because of these challenges, and for a variety of other reasons, it is common to make slight adjustments to the chemical composition to achieve the desired material performance.

Some other factors to consider when choosing a metal powder material:

• Strength (compress / tensile) – Most powder metallurgy (PM) or metal injection molding (MIM) materials can achieve required strength.
• Elongation – PM typically has low elongation (less than 10%), while MIM is more suitable for higher elongation.
• Hardness – Both PM and MIM components may harden during the initial manufacturing process, but secondary processes can be performed to increase hardness.
• Corrosion / Wear Resistance – Oil impregnation, Vacuum sealing, surface treatments and/or plating can all be applied to enhance the corrosion and wear resistance properties.
• Machinability – By selecting a material with appropriate chemical composition, machinability in PM and MIM components can be improved as necessary.

To have our engineering team review your project and recommend the ideal metal powder, contact us today.