Permanent Mold Casting Research Articles

Section thickness effect on microstructure, mechanical and electrical properties of permanent steel mold cast eutectic Al-1.8Fe alloy

Abstract A eutectic aluminum alloy, with a composition of 1.8 wt% iron, underwent casting using permanent steel mold casting (PSMC) across three distinct section thicknesses: 2mm, 8mm, and 20mm. The microstructure of the as-cast alloy was analysed by the scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The microstructure analyses indicated that the cast Al-1.8Fe alloy consisted of the primary Al phase, eutectic Al phase, micron-sized eutectic Al-Fe phase, and nano-sized eutectic Al-Fe phase. The results of tensile testing revealed notable improvements in mechanical properties for the cast Al-1.8Fe alloy as the section thickness decreased from 20mm to 2mm. Specifically, Ultimate Tensile Strength (UTS), Yield Strength (YS), elongation (ef), modulus, toughness, resilience, and electrical conductivity increased from 85.99 MPa, 28.33 MPa, 15%, 63 GPa, 8.58 MJ/m3, 6.37 kJ/m3, 48.44 %IACS to 157.74 MPa, 84.83 MPa, 19%, 66.4 GPa, 23.87 MJ/3, 54.17 kJ/m3, 51.09 %IACS, respectively. Conversely, porosity levels decreased from 5.17% to 1.87% as thickness increased from 2mm to 20mm. The enhanced mechanical properties and electrical conductivity observed in the 2mm sample are attributed to its fine microstructure and low porosity. Additionally, SEM fractography revealed that fracture behavior in PSMC Al-1.8Fe was influenced by section thickness.

Comprehensive regulation of mechanical properties and thermal conductivity of Al-Si-Fe alloys through the mixed-additive (Sr and TiB2) strategy

It is of both scientific and technical significance to adjust the balance between the thermal conductivity and mechanical performance of Al-Si alloys. In this work, we proposed a strategy of using mixed-additive to perform such tuning. A permanent mold casting (PMC) was used to optimize the as-cast properties based on the orthogonal combination of Sr and TiB2. It is anticipated that the addition of Sr addition can modify the eutectic Si, while the addition of TiB2 can refine the primary α-Al dendrites, with uncertainty of its effects on the modification efficiency of Sr. The results showed that addition of TiB2 does not impair the modification efficiency of Sr. The optimized composition contained 200 ppm Sr and 300 ppm Ti. Casting specimens were then prepared using high-pressure die casting (HPDC) process. The results demonstrated that significant reduction in the size of β-AlFeSi, eutectic Si, and α-Al grains can be achieved by HPDC process. As a result, the tensile properties have been improved. The natural effects of HPDC process on the alloy, however, such as microstructure refinement and variation in porosity, leading to deduction in the thermal conductivity to 148.5 W/(m·K). This value still exceeds conventional alloys nevertheless.

Experimental research and optimization based on response surface methodology on machining characteristics of cast Al-7Si-0.6 Mg alloy: Effects of cutting parameters and heat treatment

In this study, structural, mechanical and machining features of Al-7Si-0.6 Mg alloy manufactured by permanent mold casting (PMC) in both as-cast (AC) and T6 heat-treated (HT) conditions were investigated. Structural and mechanical properties were determined using conventional methods. Milling experiments were conducted with titanium aluminum nitride (TiAlN) coated carbide end mills in CNC milling machine under conditions of three different cutting speeds (V: 50, 80 and 110 m/min), feed rate (f: 0.08; 0.16 and 0.24 mm/rev) and constant depth of cut (DoC) (1.5 mm). It was seen that structure of AC Al-7Si-0.6 Mg comprised of aluminum-rich α-Al, coral-like eutectic Al-Si, primary Si, Mg2Si, Fe-rich plate, acicular β-Fe (β-Al5FeSi) and script-like π-Fe (π-AlSiMgFe) intermetallic phases. Eutectic Al-Si, primary Si, β-Fe and π-Fe phases in the structure of the alloy in the HT condition were partially dissolved and turned into an agglomerated and spherical state. While the hardness (HB), yield (YS) and tensile strength (TS) of the alloy raised with HT, the elongation to fracture (EF) reduced. While cutting force (CF), surface roughness (SR), built-up layer (BUL) and built-up edge (BUE) decreased with increasing V, they increased with increasing f in the milling of both cast and HT alloys. Adhered layers and feed marks were consisted of the cutted surfaces of the alloys. While the most adhered layer was observed in AC alloys at a low V (50 m/min) and high f (0.24 mm/rev) combination, the least adhered layer formation was observed at the highest V and the lowest f value in HT alloys. Optimum parameters with Response Surface Methodology (RSM) were determined as V: 125 m/min and f: 0.04 mm/rev in AC and HT cases. The statistical significance of V and f on CF and SR was revealed by analysis of variance (ANOVA), while mathematical models were improved to predict CF and SR.

Influence of nickel addition on the microstructure, mechanical, and wear properties of Zn‐40Al‐2Cu alloy

AbstractTo study the influence of nickel addition on the microstructure, mechanical and lubricated wear properties of Zn‐40Al‐2Cu alloy, one ternary and five quaternary Zn‐40Al‐2Cu‐(0.5‐2.5)Ni alloys were made by permanent mold casting. The wear behavior of these alloys was studied using a block‐on‐cylinder type test machine, after examining their microstructural and mechanical features. The microstructure of Zn‐40Al‐2Cu alloy was comprised of aluminum‐rich α dendrites and a eutectoid α+η phase mixture. The addition of nickel caused the formation of intermetallic Al3Ni particles in the microstructure of this alloy. As the nickel content of alloys increased their hardness, friction coefficient, working temperature, and average surface roughness increased to certain extents but their strength, ductility, impact resistance, and wear volume decreased. However, the values of their wear volume and average surface roughness exhibited opposite changes with increasing nickel content. The worn surfaces of Zn‐40Al‐2Cu‐Ni alloys were observed to be characterized by smearing and scratching marks. Furthermore, the wear and mechanical properties of these alloys were correlated, and the results were discussed in terms of their microstructural features. Finally, it may be concluded that the nickel addition adversely affects the ductility of Zn‐40Al‐2Cu alloy but increases its wear resistance.

Description of component distortion in aluminum gravity die casting as a result of hindered shrinkage and evaluation of numerical predictions

AbstractDeviation from the nominal dimension in the sense of component distortion is a quality‐reducing phenomenon in the foundry. This distortion problem as a result of impeded solidification and cooling shrinkage is of particular importance for permanent mold casting with its mechanically stiff and thermally well‐conducting molds. In studies, the temperature when the mold constraint is removed has already been identified as one of the dominant factors influencing the dimensional deviations of the casting. So far, however, no clear dependencies have been described. In the present work, the temperature up to the removal of the mold constraint is varied from near solidus to ambient temperature on a specially designed permanent mold casting made of AlSi7Mg0.3. This is compared with thermally and mechanically coupled finite elements method calculations of the investigated test geometry and the resulting component distortions. Finally, the applicability of the distortion prediction for the development of compensation strategies is evaluated.

Effect of sodium content on the structure and mechanical properties of silicon bronze (Cu-3wt%Si alloys)

In the present study, the effect of sodium content on the structure and mechanical properties of Cu-3wt%Si alloys were investigated. The experimental alloys were produced with various sodium concentrations of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2 and 3% by weight using permanent mould casting technique. Tensile and hardness tests were carried out on the cast samples. Microstructures of the specimens were also analysed using optical microscopy. The results indicated that the addition of sodium to Cu-3wt%Si alloy refined and modified the structure of the alloy resulting in improvement in the ultimate tensile strength and hardness of the experimental alloy by 453.85% and 58.82% respectively at 1.5wt%Na content and percentage elongation by 168.81% at 0.1wt%Na content. The addition of sodium also led to the formation of the Na1.44Si136 intermetallic phase which further contributed to the increase in strength and hardness of the alloy.

Deep learning–based inline monitoring approach of mold coating thickness for Al-Si alloy permanent mold casting

AbstractIn the permanent mold casting process, the distribution of mold coating thickness is a significant variable with respect to the coating’s thermal resistance, as it strongly influences the mechanical properties of cast parts and the thermal erosion of expensive molds. However, efficient online coating thickness measurement is challenging due to the high working temperatures of the molds. To address this, we propose an indirect monitoring concept based on the analysis of the as-cast surface corresponding to the coated area. Our previous research proves linear correlations between the as-cast surface roughness parameter known as arithmetical mean height (Sa) and the coating thickness for various coating materials. Based on these correlations, we can derive the coating thickness from the analysis of the corresponding as-cast surface. In this work, we introduce a method to quickly evaluate the as-cast surface roughness by analyzing optical images with a deep-learning model. We tested six different models due to their high accuracies on ImageNet: Vision Transformer (ViT), Multi-Axis Vision Transformer (MaxViT), EfficientNetV2-S/M, MobileNetV3, Densely Connected Convolutional Networks (DenseNet), and Wide Residual Networks (Wide ResNet). The results show that the Wide ResNet50-2 model achieves the lowest mean absolute error (MAE) value of 1.060 µm and the highest R-squared (R2) value of 0.918, and EfficientNetV2-M reaches the highest prediction accuracy of 98.39% on the test set. The absolute error of the surface roughness prediction remains well within an acceptable tolerance of ca. 2 µm for the top three models. The findings presented in this paper hold significant importance for the development of an affordable and efficient online method to evaluate mold coating thickness. In future work, we plan to enrich the sample dataset to further enhance the stability of prediction accuracy.

Effect of Sn Addition on the Microstructure and Age-Hardening Response of a Zn-4Cu Alloy

The aim of this research is to assess the influence of Sn inclusion on the microstructure evolution and age-hardening response of a Zn-4Cu alloy. This is the first study to correlate the age-hardening response to the microstructure of Zn-4Cu alloy reinforced with different Sn contents. A series of Zn-4Cu-Sn alloys were successfully fabricated with different Sn concentrations in the range of 0.0–4.0 wt.% using permanent mold casting. The microstructure of Zn-4Cu-Sn alloys was investigated by means of a scanning electron microscope (SEM) attached with an energy dispersive spectroscope (EDS) and X-ray diffraction (XRD) line profile analysis. At room temperature, the Vickers microhardness measurements were used to assess the age-hardening response of alloys. The results show that the microhardness of the Zn-4Cu (ZC) binary alloy increases a little bit from 76 to 80 HV as the aging time increases from 2 to 128 h, respectively. For aging times up to 16 h, the microhardness of all Sn-containing alloys decreases but then increases again. The lowest hardness belongs to the ZC-1.5Sn alloy, and the Sn-Zn-3.0Sn alloy has the highest; the other alloys fall somewhere in between. At high aging times (64 and 128 h), the microhardness of all Sn-containing samples increased continuously with an increasing Sn content from 0.0 to 3.0 wt.%. When the Sn-containing alloys (3.5 and 4.0 wt.% Sn) were aged for 64 and 128 h, the hardness declined by 7.94% and 8.90% compared to their peak aging hardness values, respectively. By considering the structural changes that occur in the Zn-4Cu-Sn alloys, the reasons for the observed variations in microhardness data with increasing Sn content and aging time were elucidated. X-ray diffraction (XRD) data was analyzed to determine the zinc matrix’s lattice parameters, c/a ratio, and unit cell volume variations.

Phase Composition and Microstructure of Cast Al-6%Mg-2%Ca-2%Zn Alloy with Fe and Si Additions

Investigating the effect of Fe and Si is essential for any new Al-based composition, as these impurities can be easily found both after primary production and recycling. This study is dedicated to filling the gap in revealing the phase composition of an Al-6%Mg-2%Ca-2%Zn alloy after the combined and separate addition of Fe and Si. This was addressed by permanent mold casting and solid solution heat treatment. The investigation of slowly solidified samples also contributed to understanding potential phase transitions. It was found that the alloy containing 0.5%Fe can have nearly spherical intermetallics after heat treatment, whereas a higher Fe content brought the formation of a needle-shaped Al3Fe intermetallic. We explain this by the formation of a ternary α-Al + Al10CaFe2 + Al4Ca eutectic, which is more compact in as-cast condition compared to divorced binary α-Al + Al4Ca and α-Al + Al3Fe eutectics. Similarly, 0.5%Si readily incurred the formation of a needle-shaped Al2CaSi2 intermetallic, probably also by a binary reaction L → α-Al + Al2CaSi2. In the solidified samples, no Mg2Si phase was found, even in slowly solidified samples. This is contrary to the thermodynamic calculation, which suggests a peritectic reaction L + Al2CaSi2 Mg2Si. Interestingly, the addition of 0.5%Si caused an even coarser microstructure compared to the addition of 1%Fe, which caused the appearance of a primary Al3Fe phase. We conclude that the new alloy is more tolerable to Fe rather than Si. Specifically, the addition of 0.5%Fe can be added while maintaining a fine morphology of the eutectic network. It was suggested that the morphology of eutectic and solid solution hardening governed the mechanical properties. The strength of the alloys containing separate 0.5%Fe (UTS = 215 ± 8 MPa and YS 146 ± 4 = MPa) and the combined 0.5%Fe and 0.5%Si additions (UTS = 195 ± 14 MPa and YS ± 1 = 139 MPa) was not compromised compared to the alloy containing 0.5%Si (UTS 201 ± 24 = MPa and YS = 131 ± 1 MPa).

Producing Structural High Integrity Castings with Minimum Carbon Footprint with the Comptech-Rheocasting Process

Structural high vacuum die casting has been growing significantly over the past decades. It is typically done with special (primary type) alloys, special melt treatment practices, high vacuum, a carefully engineered die casting process applying many best practices in our industry. Structural die castings are growing in size and complexity and die casting machines are getting bigger and bigger - and those castings are becoming a significant challenge with current technologies. It was now found that Rheocasting - a process of preparing a semi-solid slurry (with 30-45% solid fraction) that is injected slower and in a laminar way into the cavity, can take structural die casting to completely new heights, enable the casting of parts that would otherwise be impossible to cast and at the same time reduce or eliminate some of the current problems of structural die casting. With Rheocasting, lower purity (secondary) aluminum alloys can be used and excellent properties can be achieved as cast and heat treated (T5, T6/7). Rheocasting has had a breakthrough in the telecom and other industries, but it has now been optimized to become an essential tool in the toolbox of making structural castings. This paper shows the developments that lead to the successful series production of a large (about 4’ long) hinge pillar for an Electric Vehicle (EV). It explains the challenges and how they were overcome, and some of the possibilities of the process regarding alloys, heat treatments and achievable properties. It also shows how Rheocasting can help die casters produce more complex (thin and thick walled) and very large castings with the highest integrity. It can replace structural low-pressure permanent mold (LPPM) castings and reduce wall thickness, improve tolerances and make them more economical. Rheocasting can enable die casters to enter this new market of structural castings including Gigacastings, produce parts previously thought impossible to cast (and on much smaller machines than thought), and expand the growing structural die casting market even faster and further.

Development of manufacturing technology for a hybrid induction rotor

General Motors is developing designs and manufacturing processes for new generations of electric motors intended for use in electric vehicles. There is interest in replacing the aluminum traditionally used in induction motor rotors with copper to improve motor capability. This work explored the use of casting aluminum end-rings to copper conducting bars (spokes) in the fabrication of copper rotors. Gravity casting trials were carried out in experimental foundry. Pure aluminum end-rings were overcast and interlocked over C101 copper conductor bars encapsulating a laminate stack of highly magnetic steel. Steel permanent mold was designed and constructed specifically for the project. The mold was capable of casting one end-ring of the rotor at a time and allowed for the assembly to be reoriented for casting of the opposite end-ring. The objective of this work is to investigate the effects of intermetallic compound (IMC) formation at the interfaces of cast-bonded Cu-Al bars on the rotor mechanical integrity and electrical resistance. The Cu-Al bonding strength was measured by tension tests, and the influence of IMC layer variation on the tension load and electrical resistance were analysed. This research phase showed that sufficient bonding and interlocking were achieved among the aluminum and copper by using a special feature and/or flux at the bar ends in the permanent mold casting process. The paper reviews the data collected for evaluation of the quality of hybrid rotor cage.

RAFFMETAL EN AB-Al Si9Mg (EN AB-43300)

Abstract Raffmetal EN AB-Al Si9Mg (EN AB-43300) is a heat-treatable, aluminum-silicon-magnesium casting alloy in ingot form for remelting. It is used extensively for producing sand and permanent mold castings for applications requiring a combination of excellent casting characteristics, high strength with excellent ductility, and good corrosion resistance. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on casting, heat treating, and machining. Filing Code: Al-500. Producer or source: Raffmetal S.p.A.

RIO TINTO A356.2

Abstract Rio Tinto A356.2 is a heat-treatable, aluminum-silicon-magnesium casting alloy (3xx.x series) that is available in the ingot form for remelting. It is used extensively for producing general-purpose sand and permanent mold castings that require a combination of medium strength with good elongation, very good corrosion resistance, and excellent casting characteristics. Alloy A356.0, which is a higher purity, low iron version of alloy 356.0, provides better elongation and somewhat higher tensile strength. Alloy A356.0 is used in premium, higher strength applications and is used extensively in safety critical applications. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength. It also includes information on corrosion resistance as well as casting, heat treating, and machining. Filing Code: Al-499. Producer or source: Rio Tinto Limited.

RIO TINTO 356.2

Abstract Rio Tinto 356.2 is a heat-treatable aluminum-silicon-magnesium casting alloy (3xx.x series) that is available in the ingot form for remelting. It is used extensively for producing general purpose sand and permanent mold castings that require a combination of medium strength, very good corrosion resistance, and excellent casting characteristics. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength as well as fatigue. It also includes information on corrosion resistance as well as casting, heat treating, and machining. Filing Code: Al-498. Producer or source: Rio Tinto Limited.

Evolution of Microstructure, Mechanical Properties, and Corrosion Resistance of Mg-2.2Gd-2.2Zn-0.2Ca (wt%) Alloy by Extrusion at Various Temperatures.

The current investigation involved casting the Mg-2.2Gd-2.2Zn-0.2Ca (wt%) alloy (GZX220) through permanent mold casting, followed by homogenization at 400 °C for 24 h and extrusion at 250 °C, 300 °C, 350 °C, and 400 °C. Microstructure investigations revealed that α-Mg, Mg-Gd, and Mg-Gd-Zn intermetallic phases were present in the as-cast alloy. Following the homogenization treatment, a majority of these intermetallic particles underwent partial dissolution into the matrix phase. α-Mg grains exhibited a considerable refinement by extrusion due to dynamic recrystallization (DRX). At low extrusion temperatures, higher basal texture intensities were observed. The mechanical properties were remarkably enhanced after the extrusion process. However, a consistent decline in strength was observed with the rise in extrusion temperature. The corrosion performance of the as-cast GZX220 alloy was reduced by homogenization because of the lack of corrosion barrier effect of secondary phases. A significant enhancement of corrosion resistance was achieved by the extrusion process.

Simulation of Commencement and Size of the Hot Spot in Permanent Mould Casting

The foundry casting process is complex and takes various stages to produce the desired component; as a result, simulation is necessary before manufacturing. Hot spots are areas that become thermally isolated and take the longest to cool, resulting in cavities during the solidification of the casting. So it is important to know about the hot spot location and size so that any casting designer can identify the hot spot behaviours before the casting. To predict the initiation of the hot spot, a 3D aluminium permanent mould casting model has been developed by Ansys Fluent. The suitable boundary and initial conditions such as temperature, pressure, convectional heat transfer coefficient, etc. are reasonably established in the simulation of Ansys Fluent. The simulation has been performed for varied pouring parameters i.e. pouring velocity and pouring temperature, to examine the beginning of hot spots. This study can predict the position and approximate size of the hot spots for various pouring conditions and it is found that a hot spot is commonly located below the riser.

Influence of transition elements (Zr, V, and Mo) on microstructure and tensile properties of AlSi8Mg casting alloys

ABSTRACT The influence of the additions of transition elements (Zr, V, and Mo) on microstructure, precipitation behaviour and tensile properties of Al–8%Si–0.3%Mg permanent mould castings were investigated. It reveals that the presence of the transition elements increased the solute concentration in aluminium matrix, refined eutectic Si particles, and reduced the length and aspect ratio of intermetallic phases in as-cast microstructure. Moreover, the transition element addition promoted the formation of solute cluster and increased the number density of β′ precipitates and dispersoids during T6 heat treatment. The additions of Zr, V, and Mo considerably improved the tensile strengths and elongation in both as-cast and T6 conditions. The effects of the combined addition of Zr, V, and Mo on the microstructure, precipitation behaviour, and tensile properties were stronger than that of the addition of Zr and V.

Performance evaluation of different carbide inserts in turning of newly developed Al‐12Si‐0.1Sr alloy

AbstractAn Al‐12Si‐0.1Sr alloy ingot was manufactured using a permanent mold casting technique. The microstructure and mechanical properties of this alloy were researched. Effects of different cutting conditions (cutting speed‐V: 200 m/min, 300 m/min, and 400 m/min and feed rate‐f: 0.05 mm/rev, 0.1 mm/rev, and 0.15 mm/rev) on the cutting force (F) and surface roughness (Ra) during machining using uncoated and physical vapor deposition‐ titanium aluminum nitride coated carbide inserts were also revealed. Microstructure of the alloys consists of α phase, intermetallic δ and Al4Sr phases, thin spherical eutectic, and irregular coarse‐shaped primary silicon particles. Cutting force and surface roughness decreased with the increased cutting speed during turning with uncoated, and titanium aluminum nitride coated inserts while they increased feed rate. A built‐up edge and built‐up layer were formed in both cutting inserts. The built‐up edge and built‐up layer decreased with increasing cutting speed and increased feed rate. The cutting force, surface roughness, built‐up edge, and built‐up layer were lower in uncoated inserts compared to the titanium aluminum nitride coated inserts.

Modeling the Effect of Pour Height, Casting Temperature and Die Preheating Temperature on the Fluidity of Different Section Thicknesses in Permanent Mold Casting of Al12Si Alloys

The first and most important step of the casting method is that the liquid metal completely fills the mold cavity. One of the common mistakes in the casting process is that the liquid metal does not fully fill the mold cavity. For this reason, there is a need to improve the fluidity properties of aluminum alloys, the usage area of which is expanding thanks to its many advantageous properties. The aim of this study is to examine the parameters affecting the fluidity in the casting of Al12Si alloy by modeling techniques. The effects of varying pouring height, casting temperature and mold preheating temperature on fluidity in different section thicknesses were investigated in permanent mold casting. A specially designed mold with 2 mm, 4 mm, 6 mm and 8 mm section thickness was used in the study. Modeling studies were carried out with the FlowCast filling module, which is integrated into the SolidCast Casting simulation program. When the results are examined; It has been determined that all parameters play an active role on fluidity and different filling levels in different section thicknesses.

금형 주조 대형 펜듈럼 밸브 바디의 최적 공정 조건 결정을 위한 열변형 거동 분석

The aim of this study is to investigate the process factors that affect the thermal deformation of a product during permanent mold casting using the commercial analysis program, Abaqus. The permanent mold casting process was implemented in the analysis program to configure the optimal process conditions. In addition, the deformation pattern generated by heat was analyzed during the manufacturing process of a product with a thin hollow wall. Because the product had a thin top and bottom and was deformed through the expansions of the core and chill, which combined inside during casting, the removal time of the core had the most significant effect on the deformation. The accuracy was reviewed by comparing the simulation deformation results under the optimal process conditions with the actual measurement results of the prototype.