The Effect of Processing Parameters on Microstructure and Mechanical Properties of Sintered Structural Steels Based on Prealloyed Powders / Wpływ Parametrów Wytwarzania Na Strukturę I Własności Mechaniczne Spiekanych Stali Wykonanych Na Bazie Proszków Stopowych

Abstract

The object of the study was to evaluate the effect of production parameters on the structure and mechanical properties of Cr and Cr-Mo PM steels. The measurements were performed on sintered steels made from commercial Höganäs pre-alloyed powders: Astaloy CrA, Astaloy CrL and Astaloy CrM mixed with carbon, added in the form of graphite powder grade C-UF.Following mixing in a Turbula mixer for 30 minutes, green compacts were single pressed at 660 MPa according to PNEN ISO 2740 standard. Sintering was carried out in a laboratory horizontal furnace at 1120°C and 1250°C for 60 minutes, in 5%H2-95%N2atmosphere. After sintering, the samples were tempered at 200°C for 60 minutes in air. The steels are characterized by ferritic - pearlitic, bainitic - ferritic and bainitic structures.Following mechanical testing, it can be assumed that steel based on Astaloy CrA pre-alloyed powder could be an alternative material for steels based on Astaloy CrL powder. These steels sintered at 1250°C with 0.6% C had tensile strengths about 650 MPa, offset yield strengths about 300 MPa, elongations about 8.50 %, TRSs about 1100 MPa, hardnesses 220 HV.