Samples of ductile iron alloyed with 0.88 % Ni with a nodule count of 606, 523, and 290 nod/mm2 were obtained from sand cast plates of different thickness in the range from 8.46 to 25.4 mm. The effect of the nodule count was evaluated during the austempering process held at 285?C and austempering times of 15, 30, 45, 60, 70, and 90 min. The volume fraction of high carbon austenite was increased when the nodule count was increased, however, the carbon content of the high carbon austenite kept almost constant. The process window was narrow, requiring a lower austempering time when the nodule count was increased. The combination of a higher nodule count and low austempering temperature allows obtaining a fine ausferritic microstructure which leads higher Brinell hardness and tensile strength. The process window was determined by XRD measurements and it is in good agreement with the microstructural and hardness evolution as the austempering time was increased.
Influence of nIckel addItIon and caStIng ModuluS on the propertIeS of hypo-eutectIc ductIle caSt Iron e. colin-garcía a , a. cruz-ramírez a* , g. reyes-castellanos a , J.a. romero-Serrano a , r.g. Sánchez-alvarado a , M. hernández-chávez b a
Low manganese and sulfur gray irons were produced by adding inoculant base Fe-Si with small amounts of Al and Ca in the ladle. The effect of the cast thickness, inoculant amount and shakeout time of the green sand molds were studied on the graphite flake formation by microscopically techniques. A thermodynamic analysis was carried out for the cast iron produced with the FactSage 7.2 software. Stability phase diagrams were obtained for both gray cast irons to different manganese (0.1 to 0.9 wt.%) and sulfur (0.01 to 0.12 wt.%) amounts to 1150°C. It was shown that lower amounts of manganese and sulfur allow forming the 3Al 2 O 3 •2SiO 2 , Al 2 O 3 , and ZrO 2 solid compounds. The thermodynamic results match with those obtained by SEM-EDS. It is possible to form MnS particles in the liquid phase when the solubility product (%Mn) × (%S) equals 0.042 and 0.039 for heats A and B, respectively.
An initial assessment of the gray cast irons production by injecting an inoculant with a conveying gas into a molten iron bath was evaluated at a laboratory scale. A numerical simulation was carried out to determine the hydrodynamic behavior between the inoculant particles injected into the molten iron. It was determined that an optimal interaction between the particles with the molten iron occurs at a lance depth of 7 cm and for the particle sizes fine (211 to 297 ?m) and medium (421 to 590 ?m), the residence time was of 0.38 and 0.4 s, respectively. The melting time was calculated at 0.0008 and 0.003 s for the particle sizes fine and medium, respectively. So, after injection, the FeSi of the inoculant melts quickly, releasing the elements of the inoculant which interact with the molten iron and forms oxides and sulfides creating nucleating sites during solidification. The injection technique allows obtaining a type-A graphite distribution for the fine and medium particle sizes. The number of eutectic cells was increased when the inoculant particle size was decreased despite of the low graphitisers elements, and manganese contents used in the gray cast iron manufacturing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.