High Density Sinter-Hardened Materials with High Performance Lubricant
Heat-treating is a secondary process that uses heating and rapid cooling to develop a martensitic microstructure. While heat treatment is utilized to achieve higher mechanical properties and improve overall part performance, the addition of secondary operations such as quenching increase overall fabrication costs compared to single operation sintering. Sinter hardening is an operation that combines both conventional sintering and secondary heat treatment into a single process by using accelerated cooling in the sintering furnace. Prealloyed material systems that yield high hardenability, such as those alloyed with chromium and molybdenum, are capable of developing small percentages of martensite during conventional sintering. By utilizing accelerated cooling during the sintering process, these materials are capable of achieving microstructures and mechanical properties equal to or greater than heat-treated components. However, one of the drawbacks to using prealloyed base iron is that they have lower compressibility compared to standard iron powder. Because of this, specially designed lubricants are an important development to achieve the highest densities possible. A new lubricant system has been developed which provides improved density and ejection performance. The mechanical properties of prealloyed chromium materials with the high performance lubricant will be compared to other sinter hardened materials and lubricant systems.