Approaches to Reach Fully Dense Powder Metallurgical Materials

High-performance applications of powder metallurgy (PM) steel components are limited by the presence of porosity which contributes to the inferior properties as compared to the wrought material. PM steels, in order to meet the performance demand, require a fully dense material for improved properties. In this study, enhanced densification is achieved through several process routes, such as (1) liquid phase sintering with master alloy, (2) double pressing-double sintering, (3) cold isostatic pressing followed by high-temperature sintering, and (4) high velocity compaction. All these approaches ensure surface pore closure by reaching density levels > 95 % after sintering and capsule free hot isostatic pressing is performed to reach full densification. The proposed routes give the flexibility in terms of positioning the PM parts in terms of size and volume. The above processing methods are based on the utilisation of the low alloyed powder which brings cost competitiveness in addition to the capsule free hot isostatic pressing for reaching fully dense PM steels.