Wettability and mechanical properties assessment of Nano TiO2 and Armco Iron system

The preliminary results of this investigation may help to determine the suitability of the TiO2 nanopowder to be added in a liquid iron based matrix in order to improve mechanical properties by a fine distribution of them in the metallic alloy. Further works include Armco Iron reinforcement by levitation melting furnace technique.Peer reviewe

Wetting behavior of sintered nanocrystalline powders by armco Fe and 22CrNiMoV5-3 steel grade using sessile drop wettability technique

The wettability of sintered nanocrystalline oxide powders (CeO2, TiO2, Y3Al5O12, and ZrO2-yttria stabilized) and Al 2O3 basis powder (60-70% purity) (product originated in the secondary aluminium production, composed mainly of nano and micrometric aluminium oxide) by liquid Armco Fe and by 22CrNiMoV5-3 steel grade was studied using sessile drop wettability technique. The powders were pressed and sintered under different pressures, heating rates and holding times. The later grinding and polishing surface treatments were characterized by infinite focus microscope. The wetting experiments were carried out under pure Ar atmosphere. A small piece of Armco Fe and steel grade was melted on sintered nano oxides, heating up to 1 600°C with a holding time of 10 minutes for each experiment. The contact angles were measured and chemical analyses were conducted on tested samples to characterize the wetting reactions. It was found that sintered nano TiO2 not only suffered considerable wetting by Armco Fe and 22CrNiMoV5-3 steel in both cases, but also reacted with the substrate to form ilmenite and pseudobrookite. The CeO2 substrate and Armco Fe system also showed good wetting behavior. In general terms, it was concluded that wettability was affected by substrate chemical composition, and surface characteristics by sintering conditions. The preliminary results of this investigation may help to determine the suitability of the nanoparticle to be added in a liquid iron based matrix in order to influence the microstructure evolution improving mechanical properties by a fine distribution in the metallic alloy.Peer reviewe

Failure assessment in a h10 hot die forging tool related to thermal fatigue

A failure analysis has been performed to investigate the root cause for the rejection of the H10 (DIN 1.2365) hot work tool steel of the Hatebur forging machine. The punch is subjected to intensive thermal shocks, cyclically variable loads and high pressure at high temperatures. Although several surface defects are found related to different degradation phenomena, the higher thermal expansion occurred at the surface, compared with the inner part of the die, makes thermal fatigue the main failure responsible. In fact, thermal conductivity of an alloy will depend upon temperature and microstructure and therefore time and of course chemical composition. Damage analysis including dimensional control, surface analysis and metallographic analysis is completed by ThermoCalc and JMatPro calculations done for the standard 1.2365 tool steel. These are very useful tools to know in advance which are the stability ranges of the phases present (at equilibrium and nonequilibrium conditions), the elements in solid solution, the nature of the carbides, CCT curves and some other features for a better understanding of the failure analysis of the described system.Peer reviewe