PM Structural Parts

The Metal Powder Industries Federation (MPIF) uses minimum strength values for Powder Metallurgy (PM) materials in structural applications. These values guide PM part design. The PM process can achieve equivalent tensile strengths by varying chemical composition, particle configuration, density, and processing techniques. Along with minimum strength values, typical values for other properties help users select suitable PM materials for specific applications.

Typical values for PM materials include density, hardness, and elongation. These values are for general guidance and are not minimum values. They vary based on component area and manufacturing process. Required property values should be discussed with the PM parts manufacturer before specification.

Ferrous PM parts with ≥0.3 wt.% carbon can be quench-hardened and tempered for increased strength and wear resistance. The degree of hardening depends on carbon content, alloying elements, and density. Tempering after quenching is required for maximum strength.

Microstructural analysis of PM parts reveals sintering degree and other critical metallurgical information. Preferred sections for analysis are interior planes parallel to the pressing direction. Various etchants and procedures are recommended for preparing PM specimens.

For as-sintered PM materials, the minimum value is the yield strength (0.2% offset) in psi or MPa. For heat-treated PM materials, the minimum value is the ultimate tensile strength. Soft-magnetic materials use coercive field strength in oersteds x 10. Tensile properties are obtained from test specimens prepared for evaluating PM materials and may differ from those of commercial parts.

The chemical composition table lists principal elements by minimum and maximum mass percentage and includes other minor elements. It specifies the material before any additional processes like oil impregnation.

Some PM materials can be quench hardened during the sintering cooling cycle, especially certain prealloyed steels and martensitic stainless steels. Tempering after sinter hardening is required for durability.

The PM material code specifies chemical composition and minimum strength. For example, FC-0208-60 indicates a PM copper steel with 2 wt.% copper, 0.8 wt.% combined carbon, and a minimum yield strength of 60,000 psi (410 MPa) in the as-sintered condition.