The structure and properties of copper infiltrated high speed steel-iron composites
Marcin Madej, Jan Leżański Akademia Górniczo-Hutnicza, Wydział Metalurgii i Inżynierii Materiałowej, al. Mickiewicza 30, 30-059 Kraków
Annals 2 No. 5, 2002 pages 292-296
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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. 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 iron additives on the microstructure and mechanical properties of copper infiltrated HSS based composites. The compositions of powder mixtures are 100% M3/2, M3/2-20%Fe, M3/2-50%Fe. 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 properties of the investigated composites are given in Table 1. The morphologies of capillaries in porous and as-sintered materials as well as microstructures of the composites are shown in Figures 5-7. From the analysis of the obtained results (Tables 1, 2) and microstructural observations it may be concluded that the microstructure is mainly affected by the manufacturing route and powders characteristics (M3/2 HSS, Höganäs iron).