Effects of the cooling rate on the crystallization behaviors of the CaO–Al2O3–B2O3–CaF2-based mold flux

The effects of the cooling rate on a new type CaO–Al2O3–B2O3–CaF2-based mold flux for high aluminum steel casting were investigated using CSLM and a high temperature tube furnace.

Numerical Simulation and Experimental Investigation on Inclusion-Argon-Liquid Steel Phenomenon in RH Refining of High-Manganese and High-Aluminum Steel

In this http://mts.hindawi.com/update/) in our Manuscript Tracking System and after you have logged in click on the ORCID link at the top of the page. This link will take you to the ORCID website where you will be able to create an account for yourself. Once you have done so, your new ORCID will be saved in our Manuscript Tracking System automatically."?>paper, factors influencing the inclusion removal in high-manganese and high-aluminum steel in RH refining process were studied by numerical simulations, production practice, and metallographic experiments. A mathematical model for inclusion removal was established, and the phenomenon of inclusions mixing in RH up-leg region was verified due to fluid circulation. Removal efficiency of RH circulation time 120 s is much better than 600 s, and it was the lowest efficiency after 600 s. After 600 s circulation time, it shall not apply in production practice. The mass concentration of inclusions in practical steel was 11.64% probability error than values obtained by numerical simulation, because the numerical simulation did not consider the problem of inclusions adsorbing to the walls of refractory materials and corrosion of refractories. This work lays the foundation for the optimization and upgrading of process technology and establishes big data for full automation of RH out of furnace refining.

Crystallization Products and Structural Characterization of CaO-SiO2-Based Mold Fluxes with Varying Al2O3/SiO2 Ratios

During the casting of high aluminum steel, the dramatic increase in the Al2O3/SiO2 ratio is inevitable, resulting in significant changes of the crystallization behavior, which would result in heat transfer and lubrication problems. Crystallization products and structure characterization of glassy CaO-SiO2-based mold fluxes with different Al2O3/SiO2 ratios were experimentally investigated using a differential scanning calorimetry technique and Raman spectroscopy. With increasing Al2O3/SiO2 ratios, the following results were obtained. The crystallization temperature and the crystallization products are changed. With increasing Al2O3/SiO2 ratios from 0.088 to 0.151, the crystallization temperature first increases greatly from 1152 °C to 1354 °C, and then moderately increases. The crystallization ability of the mold flux is strengthened. The species of the precipitated crystalline phase change from two kinds, i.e., Ca4Si2O7F2 and Ca2SiO4, to four kinds, i.e., Ca4Si2O7F2, Ca2SiO4, 2CaO·Al2O3·SiO2 and Ca12Al14O32F2, the crystallization ability of Ca4Si2O7F2 is gradually attenuated, but other species show the opposite trend. The results of Raman spectroscopy indicate that Al3+ mainly acts as a network former by the information of [AlO4]-tetrahedral structural units, which can connect with [SiO4]-tetrahedral by the formation of new bridge oxygen of Al–O–Si linkage, but there is no formation of Al–O–Al linkage. The linkage of Al–O–Si increases and that of Si–O–Si decreases. The polymerization degree of the network and the average number of bridging oxygens decrease. Further, the relatively strong Si–O–Si linkage gradually decreases and the relatively weak Al–O–Si gradually increases. The change of the crystalline phase was interpreted from the phase diagram and structure.

Effect of B2O3 on Slag-Metal Reaction between CaO-Al2O3-Based Mold Flux and High Aluminum Steel

The effect of B2O3 on slag-metal reaction between CaO-Al2O3-based mold flux and high aluminum steel was investigated. The results showed that the addition of 5 % B2O3, the slag-metal reaction hardly occurred. When the content of B2O3 was increased, the reaction rate increased rapidly. This indicated if only considering the slag-metal reaction, it’s better for high aluminum steel casting if the addition content of B2O3 is less than 5%. The chemical reaction was greatly influenced by the reaction time. With higher content of aluminum ([Al]=0.1 %), the early stage of reaction was greatly affected by the reaction time, and furtherly, the influence was decreased. When the aluminum content was increased, the effect of [Al] on the slag-metal reaction was comparatively small in the initial 10 min, and the content of [B] was increased slightly. But when the reaction time increased to 1 hour, the slag-metal reaction acutely occurred, and the content of [B] increased rapidly.