TABLE OF CONTENTS Diffusion alloyed steels are a group of steels that have been used successfully in the production of structural parts for high strength and high precision applications because of their better technical properties and their overall ease of manufacture.
These steels are alloyed in varying combinations and amounts with nickel, copper, and molybdenum. They are prepared as 'non segregable mixes', exhibiting similar compactibility and sintered microstructures as the respective mixes, with appropriate amounts of graphite. According to the base powder used in their preparation, diffusion bonded type alloys (frequently known under H gan s designation 'Distaloy') can be divided roughly into two groups. The first group is formed by those alloys prepared on the basis of plain iron powders (mixed powder systems) and the second one consists of the alloys prepared on the basis of prealloyed Fe-Mo powders (hybrid material systems).
According to this classification, the first group incorporates: a) medium alloyed Fe-1.75Ni-1.5Cu-0.5Mo steels based on sponge iron powder (Distaloy SA) and on atomised iron powder (Distaloy AB), and b) higher alloyed Fe-4Ni-1.5Cu-0.5Mo steels based on sponge iron powder (Distaloy SE) and on atomised iron powder (Distaloy AE). The base powder mixes differ in compressibility depending on the base iron powder grade. At suitable carbon contents, even the as-sintered materials exhibit high strength and hardness and are also suitable for heat treatment. A typical microstructure is shown in Fig. 7.40a.
