Warm Compaction Forming of a Binder-Treated Fe-Base Material

It is well known that increasing density is the best way to increase the performance of powder metallurgy (PM) parts. Conventional PM processing can produce iron-base parts with density less than 7.2 g/cm3. Their mechanical properties are substantially less than their full density counterpart. With minor modification on the conventional PM equipment, green compact density of 7.4 g/cm3 can be obtained by warm compaction. Binder-treated technique is an efficient and cost-effective process that can produce high green strength compacts with consistent alloy content and reduce dusting. The mixed powder is bonded by organic binder, which is burned out during sintering. In this study, high density and high green strength iron-base compacts were obtained by warm compacting binder-treated iron-base powder at 150°C using a pressure of 700 MPa. Sintered compact with density of 7.38 g/cm3, tensile strength of 624 MPa and elongation of 4.8% can be obtained after sintering at 1120°C for 1 h under a cracked ammonia atmosphere. Effects of warm compaction parameters, such as binder concentration and compaction temperature, on the properties of the sintered material were investigated. Green and sintered compact densities, spring back effect and mechanical property were measured and analyzed. Present paper demonstrated that binder-treated warm compaction process can not only reduce the powder segregation and increase the green compact strength, but also reduce the use of additives such as lubricant and binder.