The analysis of properties sintered and infiltrated high speed steel based composites
Marcin Madej, Jan Leżański Akademia Górniczo-Hutnicza, Zakład Metaloznawstwa i Metalurgii Proszków, al. Mickiewicza 30, 30-059 Kraków
Annals 4 No. 12, 2004 pages 409-413
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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 for manufacture of valve train components such as valve seat inserts and valve guides. The problem of high sintering temperatures and direct supersolidus sintering can be overcome by addition of Cu, graphite, Cu-P alloy powders to high speed steels, high speed steel chemically coated with 2÷10% Cu or by infiltration of high-speed steel skeleton with liquid cooper. Attempts have been made to describe the chemical composition and the production process parameter strength and wear resistance high speed steel based composites. The compositions of powder mixtures are 100% M3/2, M3/2 + 7,5% Cu, M3/2 + 15% Cu and M3/2 + 30% Cu. The powders mixtures 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. Attempts include the as sintered and as-infiltrated density (Fig. 2). Brinell hardness (Fig. 4), benching stress (Fig. 5). Microstructural analysis of the as sintered structures required to use a number of techniques, including optical microscopy (Figs 6, 7). 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 same situation has been found in as sintered materials with additions of Cu. 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. Key words: sintering, infiltration, high speed steel