Shrinkage and porosity defects critically impair the quality of 12Cr2Mo1V alloy ingots used in high-temperature, high-pressure applications. This study employs finite-element simulations to systematically investigate the effects of pouring temperature, mold preheating temperature, and pouring rate on the filling and solidification behavior of this alloy during low-speed metal mold gravity casting. A numerical model incorporating the Niyama criterion was established and validated against metallographic observations to predict defect formation. The results demonstrate that increasing the pouring temperature from 1535 to 1655 °C causes porosity volume to first decrease and then increase, while defect locations progressively shift away from the riser. Elevating the mold preheating temperature from 150 to 350 °C prolongs solidification time by up to 22
The increasing demand for advanced lightweight engineering materials has accelerated the development of hybrid aluminum matrix composites with enhanced mechanical and tribological performance. However, the relatively low hardness and poor wear resistance of conventional Al-Mg-Si alloys limit their application under severe service conditions, thereby necessitating the incorporation of suitable reinforcements to improve their overall performance. The present work investigates the synergistic influence of in-situ formed titanium diboride (TiB2) particle and graphite (Gr) reinforcements on the microstructural evolution, mechanical, and tribological properties of AA6063 alloy-based HMMCs. Hybrid metal matrix composites containing 2 to 6 wt. K_2 TiF_6 and KBF_4 salts for the in-situ synthesis of TiB2. The developed composites were characterized using optical microscopy, FESEM, and X-ray diffraction to examine the phase formation and microstructure. The mechanical properties of developed MMCs are measured through tensile strength, Brinell hardness, and impact properties; however, the tribological properties are measured through using a pin-on-disk wear testing setup under dry sliding conditions. Taguchi-based analysis was employed to optimize the wear parameters. The experimental results are analyzed using the signal-to-noise (S/N) ratio and analysis of variance (ANOVA) to determine the optimal process parameters and their significance. The results showed that there is an improvement in mechanical properties greatly with TiB2 content increasing due to an effective load transfer and grain refinement. The composite with 4 wt.
This study presents a simulation-driven surrogate-based optimization framework for runner geometry design in vertical centrifugal casting of Ti-6Al-4V alloy components. The inclination angles of two runner regions ( θ _A and θ _B ) were selected as design variables, and their effects on filling time, misrun occurrence, and shrinkage formation were systematically investigated. Sixteen discrete configurations were evaluated using thermo-fluid and solidification simulations to characterize the performance trends within a predefined angular domain. The configuration with θ _A = 40^∘ and θ _B = 10^∘ exhibited the best overall balance among the evaluated cases. To reduce computational cost while maintaining predictive reliability, Gaussian process surrogate models were constructed for the objective function and the misrun constraint and integrated with constrained Bayesian optimization. The proposed framework identified an optimal region near θ _A = 40^∘ and θ _B ≈ 12^∘ , which lies within the same dominant low-objective basin as the best discrete configuration. This result indicates that surrogate-assisted continuous optimization refines the optimal region beyond the discretized grid resolution rather than producing a fundamentally different solution. Physically, θ _A and θ _B are treated as coupled runner-geometry variables within the surrogate-based optimization framework. Their combined configuration affects the local redirection and dispersion of the centrally introduced melt near the gate region, thereby influencing filling uniformity, misrun tendency, and shrinkage-related responses. The proposed methodology significantly reduces the number of required simulations and provides a computationally efficient and physically consistent approach for systematic runner geometry optimization in centrifugal casting processes.
The creep behaviour of two austenitic heat-resistant steels, GX40CrNiSi25-20 and a newly developed GX40CrNiSi20-20 alloy modified with Mo, Nb, and W, was investigated using creep test specimens produced via ablation sand casting and compared to the conventional sand-casting process. Creep tests were conducted at 930 °C/48 MPa and at 950 °C/25 MPa. Ablation casting extended the creep rupture life of both alloys compared to the conventional sand-casting process. This improvement was especially pronounced in the modified alloy, which exhibited the lowest minimum creep rate and the longest secondary creep stage. Microstructural analysis revealed that ablation casting resulted in a refined microstructure, characterized by reduced secondary dendrite arm spacing (SDAS), smaller grain size, and smaller and more uniformly distributed primary phases. These features contributed to an increase in Vickers hardness and creep resistance. Also, a change in the morphology and distribution of eutectic primary carbides was observed. In the conventionally cast GX40CrNiSi25-20 alloy, eutectic primary carbides were dispersed in the interdendritic regions, while in the ablated alloy, a continuous interdendritic carbide network was observed. For the modified GX40CrNiSi20-20 alloy, ablation casting also altered the eutectic morphology and composition, transforming the coarse binary/ternary eutectics present in the conventional casting into a finer, denser quaternary eutectic structure. This dense eutectic structure could hinder creep cavity nucleation and linkage, thereby enhancing creep resistance.
Al-Ce alloys hold considerable promise for lightweight structural applications owing to the excellent thermal stability of the AlCe3 intermetallic phase. However, their industrial adoption is constrained by the inherently low ductility arising from the continuous network-like brittle eutectic structure in the as-cast condition. This study systematically investigates the multi-scale regulatory mechanisms by which Mg alloying and Zr/Sc microalloying govern the microstructural evolution and room-temperature mechanical properties of Al-Ce-based alloys. The results demonstrate that Mg addition effectively fragments the continuous brittle eutectic network into a dispersed particulate morphology, thereby optimizing stress distribution during deformation and suppressing intergranular crack propagation. With increasing Mg content, the ultimate tensile strength initially increases and then decreases, while the elongation decreases monotonically from 5.0
Cr-Mo alloy steel is widely used for wear-resistant components subjected to combined impact and abrasive loading. In this study, Cr-Mo alloy steel was water-quenched from 840, 870, 900, and 930 °C and subsequently tempered under the same condition (300 °C for 2 h) to isolate the effect of quenching temperature. The microstructure, hardness, impact toughness, impact abrasive wear behavior, and worn-surface roughness were evaluated. Endpoint EBSD analysis showed that the retained austenite fraction increased from 0.2
The machining quality of frozen sand molds is closely related to the casting process and the final quality of high-end equipment components. To enable intelligent manufacturing of sand molds while reducing resource consumption, this study proposes a multi-objective online inspection system for CNC machining of frozen sand molds. A segmented machining-inspection strategy based on a moving sand mold is developed, enabling stage-wise online inspection on the machining line of three key quality metrics: sand removal rate, surface roughness, and dimensional accuracy. Experimental evaluation using multi-material frozen sand molds demonstrates that the relative error in sand mold forming induced by the two reciprocating motions of the proposed online inspection platform remains within 1
AA2024-SiC composites with varying silicon carbide (SiC) contents were produced through ultrasonic-assisted stir casting (UASC) at 20 kHz for 3 minutes, using 50 µm SiC particles. Experimental density increased while porosity content decreased with increasing percentage of SiC content. Further, this study revealed a uniform distribution of SiC and significant grain refinement with the implementation of SiC. The Vickers microhardness increased from 82.7 ± 10.2 HV for unreinforced AA2024 to max. of 127 ± 8.2 HV at 12 wt.
This Technical Communication analyzes and evaluates the results and major conclusion drawn by the IJMC paper titled ‘Influence of Mn and S on the Properties of Cast Iron Part III—Testing and Analysis’1 and authored by Gundlach, R. Meyer, M. and Winardi, L. That paper concluded that the mathematical product of the manganese and sulfur contents is a more accurate predictor of the mechanical properties of gray iron than the commonly accepted ratio metrics of those two elements, but this technical communication uses the published results of the subject paper1 to rebut its main conclusion and reassert the long held commonly accepted conclusion that the statistical significance of the ‘ratio’ metric dwarfs the statistical significance of the ‘product’ metric.
This study investigated the effects of different heat treatment conditions on the microstructure, mechanical properties, residual stress behavior of low-pressure die-cast aluminum alloy wheels, and impact behavior of AlSi11Mg aluminum alloys through analytical and experimental approaches. Unlike the commonly studied AlSi7Mg0.3 alloys, heat-treated AlSi11Mg alloy was selected to provide an original industrial perspective for complex wheel geometries and automotive applications. Wheel samples produced under industrial conditions were evaluated using microstructural analysis, tensile and hardness testing, Charpy impact testing, residual stress simulations, and experimental hole-drilling measurements based on ASTM E837. Microstructural analyses showed that the as-cast condition exhibited coarse dendritic structures and heterogeneous morphology associated with lower mechanical performance. T6 heat treatment significantly refined the eutectic Si morphology through spheroidization, resulting in considerable improvements in hardness, ultimate tensile strength, and yield strength. Charpy impact results revealed that different cooling conditions applied to gravity cast specimens produced no significant variation in absorbed impact energy, indicating that cooling condition alone had a limited influence on impact behavior under the investigated conditions. Residual stress analyses demonstrated that the T6 heat treatment process, particularly the quenching stage, generated the highest tensile residual stresses because of severe thermal gradients. Both simulations and hole-drilling measurements identified the hub and hub–spoke transition regions as the most critical zones for residual stress accumulation. Overall, the study demonstrated that optimization of heat treatment parameters is essential for balancing mechanical performance, impact behavior, and residual stress control in industrial AlSi11Mg wheel production.
The hot tearing susceptibility (HTS) of Mg–6Al–1Ca–xY (referred to as AX61–xY) alloys with varying Y contents (x = 0 wt
In this study, the effect of Ni, Mo and Cr on the microstructure and the electrochemical behavior of ductile cast iron was investigated and compared to a standard ductile cast iron. The studied ductile cast iron was produced in an industrial environment. Ni, Mo and Cr were finely crushed and added in powder form. Microstructural changes were evaluated using optical and scanning electron microscopies and X-ray diffraction. Corrosion tests were conducted in two different solutions, 0.5 M H2SO4 and 0.6 M NaCl, at room temperature using a three-electrode Gamry 600+ potentiostat/galvanostat. The obtained results indicated that the microstructure of the studied ductile cast iron consists of a biphasic matrix, composed of ferrite and pearlite, and nodular graphite. Addition of Ni, Mo and Cr favors the formation of M6C-type carbides, raises pearlite quantity and reduces the amount of ferrite. The added elements (Ni, Mo and Cr) significantly improve the electrochemical corrosion in both solutions. The alloyed ductile cast iron displays good corrosion resistance in 0.6 M NaCl compared to 0.5 M H2SO4.
An upgrading approach for hypereutectic Al–Si alloys was investigated through controlled segregation of Si using a unidirectional casting process. The precipitation behavior and spatial distribution of primary Si in the hypereutectic ADC14 (Al–17Si–4Cu) alloy were systematically examined at different casting speeds (0.06, 1.9, and 10 mm/s). Microstructural observations revealed that high casting speed suppresses primary Si formation due to rapid solidification, whereas intermediate speed leads to a relatively uniform distribution of primary Si. In contrast, low casting speed combined with a holding period for 2 min promotes pronounced segregation and coarsening of primary Si in localized regions. Energy-dispersive X-ray spectroscopy analysis confirmed significant fluctuations in Si concentration along the casting direction, particularly after process interruption. Based on these results, a preliminary upgrading process was proposed, involving the selective removal of Si-enriched regions followed by remelting. This approach resulted in a reduction of Si content to approximately 13.9 wt.
This case study developed in the “E E” foundry examines the possibilities for heat recovery of off-gases and preheating of the air used from coke combustion and exothermic reactions in the cupola furnace. For drafting the thermal profile and network diagram of the cupola furnace, the data have been exploited from the thermal and chemical analysis of the off-gas, cast iron, slag, and the ratios of CO2/CO. The use of off-gases of metallurgical processes will express high effects regarding the rational use of natural resources, energy, and environmental protection. The study focuses on the modifications to the technological scheme through the installation of HILDEN systems. The thermal profile, as well as the heat balance, is based on measurements and experimental demonstrations at the "E E" foundry, in Gjakova, and in accordance with them, the development of the HILDEN system has been proposed.
Conventional Al-Cu alloys exhibit severe coarsening of metastable θ′-Al2Cu precipitates and poor mechanical performance at 300–500 °C, restricting their high-temperature service applications. To address these limitations, this study explores the influence of V microalloying on the microstructure and tensile properties of T6-treated Al-6Cu-0.4Mn alloys at room temperature and 350 °C. Alloys with different V contents were prepared by casting and T6 heat treatment, and their microstructural characteristics and mechanical behaviors were systematically analyzed. The results show that V effectively refines α-Al dendrites and α-Al+θ-Al2Cu eutectic structures, with the optimal refinement achieved at 0.3 wt.
The hot-tearing susceptibility (HTS) of three experimental 6XXX-series Al alloys with controlled variations in Si, Mg, Fe, and Mn content was investigated using constrained rod casting (CRC) tests, and the effect of an Al–Ti–B grain-refining agent was also evaluated. CRC test results validated the hot-tearing indices predicted by Kou’s criterion, demonstrating strong agreement between theoretical predictions and experimental observations. Microstructural observations and fracture-surface analyses revealed that the presence of the Al15(Fe,Mn)3Si2 phase with Chinese-script morphology contributes to the formation of a strong solid skeleton in the α-Al matrix, enhancing hot-tearing resistance. In contrast, the β-Al5FeSi phase, exhibiting a plate-like morphology, acts as a stress concentrator and disrupts interdendritic feeding, promoting hot-tear initiation. The influence of adding a Ti-based grain refiner was also evaluated, as grain refinement generally reduces hot-tear propagation along intergranular voids. However, because the alloys already exhibited a fine as-cast microstructure in the CRC castings, further grain refinement yielded only a marginal decrease in hot-tearing resistance. These implications provide important insights for optimizing alloy design and process parameters, improving the structural integrity of aluminum castings for industrial applications and supporting the use of recycled feedstocks in industrial applications.
The high specific strength of Al-Cu alloys has driven their widespread implementation in industrial fields. Nevertheless, a critical limitation―namely, high hot tearing susceptibility―substantially constrains their application in critical structural components. Hot tearing susceptibility is dependent on two primary factors: the inherent characteristics of the alloying elements and the specific processing parameters employed. With respect to alloy characteristics, the stress-strain behavior of the intergranular liquid film during the terminal solidification stage is particularly critical in dictating hot tearing initiation. Conventional polycrystalline samples are rendered incapable of accurately capturing the intrinsic stress-strain characteristics of the liquid film, owing to confounding contributions from grain size variations, liquid film thickness fluctuations, and assorted defects. To circumvent these inherent limitations, a specialized apparatus was developed to directly interrogate the stress-strain response of monocrystalline intergranular liquid films. The self-developed device was employed to elucidate the effect of Mg on the stress-strain characteristics of the liquid film at the terminal solidification stage of Al-Cu alloy. The correlation between these liquid-film mechanical characteristics and hot tearing susceptibility was further examined by integrating a T-shaped mold experiment with differential thermal analysis. Additionally, ProCAST simulations were conducted to resolve the stress field evolution during solidification of the Al-5Cu-xMg alloy. The experimental findings indicate that, during hot tearing evolution, the shrinkage stresses are primarily borne by the solid-phase skeleton rather than by the liquid film. The principal contribution of the liquid film is to feed the incipient hot tears, thereby suppressing their development. The addition of Mg induced the formation of a low-melting-point Al2CuMg phase during the terminal stage of solidification. The presence of this phase increased the fracture displacement of the liquid film, prolonged the feeding time, and simultaneously lowered both the hot cracking initiation temperature and the dendrite coherency temperature, thus reducing the hot tearing susceptibility of the alloy. The simulation results for the stress field and hot cracking indicators during alloy solidification agreed well with the experimental observations.
Effects of key processing parameters including ingate velocity (IV) and intensification pressure (IP), on the average/maximum sizes, volume fraction and fractal dimension of defects/porosities and grain size, and mechanical properties of die-cast Al7SiMnMg alloy wheels, were investigated by experiments and assisted with AI and intelligent prediction. Experiments show that IV considerably influences the maximum size of defects/porosities, which decreases considerably from 35.3 μm to 18μm with increasing IVs from 15 m/s to 35 m/s, afterwards remains constant. The average size and volume fraction of defects/porosities can be minimized under IVs of 35–50m/s. The grain size decreases slightly from 18 μm to 15 μm with increasing IVs from 15 m/s to 75 m/s. Microstructure features excluding fractal dimension exhibit similar reduction trends at low IPs of 300–600 bar, afterwards the effect of IP becomes not evident. IV substantially influences elongation, which reaches a high level of 10
Al-ceramic particulate metal matrix composites are promising materials for structural and advanced engineering applications because of their enhanced mechanical properties and low weight. However, metallurgical slags, including electric arc furnace (EAF), ladle refining furnace (LRF), copper (Cu), manganese (Mn), and aluminum (Al) slags, are generated as industrial by-products and represent a source of environmental contamination. In this study, the feasibility of using these metallurgical slags as reinforcement materials in an AA6063 matrix was investigated. The composites were fabricated as single and hybrid systems using stir casting followed by cumulative hot rolling. The mechanical performance was interpreted based on several strengthening mechanisms, including Orowan strengthening from finely dispersed phases, load transfer due to improved interfacial bonding, grain refinement induced by hot rolling, and dislocation strengthening caused by thermal expansion mismatch between the matrix and reinforcement. The results showed that hybrid composites containing Al and LRF slags exhibited improved properties due to the presence of spinel (MgAl2O4) and silica (SiO2) phases, which enhanced interfacial integrity and acted as barriers to dislocation motion. In addition, hot rolling significantly improved the mechanical properties of the developed composites. Among all compositions, the LRF/Cu hybrid slag composite exhibited the best overall performance, achieving a hardness of 125 HV, an ultimate tensile strength of 223 MPa, elongation of 9.8
