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Casting and Foundry Work
Published in Sherif D. El Wakil, Processes and Design for Manufacturing, 2019
The ability of the molten metal to flow easily without premature solidification is a major factor in determining the proper filling of the mold cavity. This important property is referred to as castability or, more commonly, fluidity. The higher the fluidity of a molten metal, the easier it is for that molten metal to fill thin grooves in the mold and exactly reproduce the shape of the mold cavity, thereby successfully producing castings with thinner sections. Poor fluidity leads to casting defects such as incomplete filling or misruns, especially in the thinner sections of a casting. Because fluidity is dependent mainly upon the viscosity of the molten metal, it is clear that higher temperatures improve the fluidity of molten metal and alloys, whereas the presence of impurities and nonmetallic inclusions adversely affects it.
Reaction performances of mould slags with different SiO2 contents for 321 stainless steel
Published in Canadian Metallurgical Quarterly, 2019
Zhuo Chen, Ya-Bing Zhang, Sheng-Ping He, Zhi-Rong Li, Qian Wang
The 321 Stainless Steel has been extensively used in petrochemical and chemical industry, owing to the noticeable corrosion resistance and mechanical properties [1]. In contrast, the clogging of submerged entry nozzle (SEN) and frozen steel during the casting of the Ti-bearing steel exacerbates the stream dynamics and consequently aggravates the entrapment of mould flux and fragmented inclusions as well as to decrease the quality of slabs or billets [2,3]. The operation experience in the continuous casting demonstrated that the presence of titanium with the content exceeding 0.15 wt-% in steel generally causes a significant increase in the severity of nozzle clogging and deteriorates the castability owing to the precipitation of TiN and other non-metallic [4–7]. Although cause and countermeasure of the nozzle clogging for Ti-free steel has been known [8–10], yet the corresponding mechanism is still not sufficiently elucidated.
Microstructural characterisation of Al–Si cast alloys containing rare earth additions
Published in Philosophical Magazine, 2018
E. M. Elgallad, M. F. Ibrahim, H. W. Doty, F. H. Samuel
A356 and A413 alloys are two of the most commonly used Al–Si cast alloys belonging, respectively, to the hypoeutectic and eutectic Al–Si alloy families. The A356 (Al–7%Si–0.35%Mg) alloy is widely used in automotive and engineering industries due to its good castability and machinability and high response to age-hardening, which yields various combinations of desired mechanical properties through the precipitation of Mg2Si phase precipitates [25,26]. The A413 alloy with its composition of Al-(11–13)%Si-(1–1.3)%Fe provides excellent castability coupled with high die-soldering resistance and it is, therefore, suitable for die casting food, dairy and dental equipment, street lamp housings and also intricate components for architectural, ornamental and marine applications [27,28].
Influence of transition elements (Zr, V, and Mo) on microstructure and tensile properties of AlSi8Mg casting alloys
Published in Canadian Metallurgical Quarterly, 2023
Zhan Zhang, Anil Arici, Francis Breton, X.-Gant Chen
Al–Si–Mg casting alloys are widely used in the transport industries owing to their many outstanding attributes including excellent castability and good mechanical properties [1,2]. The presence of magnesium in the hypoeutectic Al–Si alloys provides high strengths mainly by precipitation strengthening and solute solution strengthening [1,2]. Many researches have been performed to improve both strength and ductility of the alloys to meet the increasing demand of mechanical performance from industries by increasing precipitates and dispersoids, as well as modifying eutectic silicon and intermetallic compounds [3–11]. To promote the precipitation strengthening, Al–Si–Mg alloys are usually solution-treated and artificially aged to form nanosized precipitates by the decomposition of supersaturated solid solution [2]. The precipitation sequence in Al–Si–Mg alloys during aging treatment is known as follows: supersaturated solute solution → Mg and Si clusters → GP zones → β″ → β′ → β-Mg2Si [12–14]. The formation of the main strengthening phases, β″ and β′ precipitates, depends on the solute diffusion of Mg and Si in the aluminium matrix [15,16]. However, the alloying elements, particularly transition elements such as Zr and V, may influence solute diffusion because they interact with vacancies in aluminium during heat treatment [15,16]. Voncina et al. [17] reported that Zr addition accelerated precipitation of Q–Al5Cu2Mg8Si6 and β″-MgSi in AlSi10Mg alloy during aging treatment. Yuan et al. [18] found that Zn addition increased the number density of β″-MgSi precipitates in Al–Mg–Si–Cu–Mn alloys.