Engineering the structure and properties of infiltrated M3/2-WC-Cu composites due to changes in contents of wc and producing parameters
Marcin Madej, Jan Leżański Akademia Górniczo-Hutnicza, Zakład Metaloznawstwa i Metalurgii Proszków, al. Mickiewicza 30, 30-059 Kraków
Annals 3 No. 6, 2003 pages 69-74
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abstract High hardness, mechanical strength, heat resistance and wear resistance of M3/2 high speed steel (HSS) make it an attractive material. Since technological and economical considerations are equally important, infiltration of high-speed steel skeleton with liquid cooper has proved to be a suitable technique whereby fully dense material is produced at low cost. Attempts have been made to describe the influence of the production process parameters and alloying additives, such as tungsten carbide on the microstructure and mechanical properties of copper infiltrated HSS based composites. The compositions of powder mixtures are 100% M3/2, M3/2+10%WC, M3/2+30%WC. The powders were uniaxially cold compacted in a cylindrical die at 800 MPa. The green compacts were sintered in vacuum at 1150°C for 60 minutes. Thereby obtained porous skeletons were subsequently infiltrated with copper, by gravity method, in vacuum furnace at 1150°C for 15 minutes. The M3/2 grade HSS powder cannot be fully densified at a temperature as low as 1150°C and the as-sintered density is approximately equal to the green density. The dilatometr was used to detect some reaction in the sintering of the composition M3/2+30%WC. The properties of the investigated composites are given in Table 2. The morphologies of capillaries in porous and assintered materials as well as microstructures of the composites are shown in Figs 6-8. From the analysis of the obtained results (Tab. 2) and microstructural observations it may be concluded that the microstructure is mainly affected by the manufacturing route and powders characteristics (M3/2 HSS). Scanning electron microscopy (SEM) shows that in the as sintered material and copper infiltrated containing 30% tungsten carbide, the carbide phase is evenly distributed within the steel regions. Key words: high speed steel, infiltration, sintering, infiltrated composites