Sintering of grey cast iron powder recycled via jet milling

Porous grey cast iron powder metallurgy parts were made from grey cast iron powder manufactured via target jet milling of machining scraps. The powders were used in the as-milled state without any further physical or heat treatment.Sintering was conducted at 1025, 1100 and 1175 °C in an argon atmosphere and the effect of sintering temperature on microstructure, sintered density and apparent hardness of the grey cast iron specimens pressed to 5.8 g/cm3 was investigated.Although diffusion processes were partially activated at 1025 °C, it was determined that a temperature of 1175 °C proved to be the ideal temperature for solid state sintering of grey cast iron parts. The hardness value and sintered density for the specimens sintered at 1175 °C were found to be 96 BHN and 6.1 g/cm3 (around 15% porosity) respectively, all of which lends itself to promising properties for making self-lubricating bearings and parts with sliding properties.

Sintering of grey cast iron compacts were conducted in 1025, 1100 and 1175 °C in argon atmosphere. Although diffusion processes were partially activated in 1025 °C, the temperature of 1175 °C proved to be the ideal temperature for solid state sintering of grey cast iron parts.Figure optionsDownload as PowerPoint slideHighlights
► Grey cast iron sintered parts can be produced without the contribution of iron powder.
► Grey cast iron jet milled powders can be used in the as-milled state.
► 1175 °C is the ideal temperature for solid state sintering of grey cast iron parts.
► Absence of oxygen in the powders plays a major role in the successful sintering.
► Sintered parts possess promising properties for self-lubricating applications.