Abstract
Fe-1.4Cr-1.3Ni-0.7Mn-0.2Mo-0.2Si-(0.5-0.6)C steel was sintered in semi-closed containers at 1120 or 1250 °C using nitrogen or air as the furnace gas and also conventionally sintered in N₂-5%H₂. Additives, principally ferromanganese, the source of Mn vapour, aluminium or naphthalene, the source of nascent carbon, and activators were included with the specimens. Sintered density, carbon, oxygen and nitrogen contents were evaluated before mechanical testing. All mechanical properties obtained with semi-closed container sintering outperformed those resulting from comparable conventional sintering. The best combination of properties resulted from liquid phase sintering at 1250 °C in N₂ with naphthalene/Na₂CO₃ or Al/NH₄I/NaCl/AlCl₃ additives. Properties included strain-to-failure of ∼ 4.5 %, the yield stress of 374 and tensile strength of 813 MPa. Results for air as the furnace gas were slightly inferior. This opens up the possibility of using conventional air furnaces for sintering ceramics to process PM steels to (near) full density to match the properties of their wrought counterparts.

Key words
sintered steels, sintering atmospheres, alloying elements

Full text (1260 KB)