Permanent Mold Research Articles

RAFFMETAL EN AB-Al Si7Mg (EN AB-42000)

Abstract Raffmetal EN AB-Al Si7Mg (EN AB-42000) 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 good strength and ductility, and good corrosion resistance. This alloy can be produced to a wide range of mechanical properties by making small adjustments to the magnesium content and/or heat treatment. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Al-475. Producer or source: Raffmetal S.p.A.

Optimized cast components in the drive train of wind turbines and inner ring creep in the main bearing seat

Using large components made of nodular cast iron (GJS) in wind turbines enables the application of lightweight construction through the high degree of design freedom. Besides the sand-casting process, casting into a permanent metal mould, i.e. chill casting, leads to a finer microstructure and higher quasi-static mechanical properties as well as higher fatigue strength. Unfortunately, in present design methodologies specific fatigue data is only available for sand cast and not for chilled cast GJS. Thus, lightweight design strategies for large, chilled cast components are not achievable, which led to the publicly funded project “Gusswelle”. Based on material investigations of EN-GJS-400-18-LT chill cast, an optimized hollow rotor shaft is developed. The design process and the resulting shaft design are presented. The optimized hollow rotor shaft prototype will be tested on a full-scale test bench to validate the design methodology. The intended validation plan as well as the test bench setup is shown in this paper. Furthermore, the decreasing wall thickness influences the interference fit between main bearing and hollow rotor shaft. Thus, through the applied bending moment, inner ring creep is more probable to occur in the main bearing seat. The creeping behaviour is investigated with finite element simulations and a measuring method is presented.

Enhanced mechanical properties of 6082 aluminum alloy via SiC addition combined with squeeze casting

In order to improve mechanical properties of 6082 aluminum alloy, the SiCp/Al 6082 composites were prepared by the addition of the micron-sized SiC particles combined with the squeeze casting. The effects of the SiCp content and squeeze casting on the microstructure and mechanical properties of the 6082 aluminum alloy were investigated by SEM, EDS, TEM, tensile testing and hardness testing analysis methods. Research results exhibited that the SiCp content and squeeze casting had a significant impact on the microstructure and mechanical properties of the 6082 aluminum alloy. The addition of the SiCp refined the grain size of the 6082 aluminum alloy while caused the increase of the porosity with increasing the SiCp content, especially in the permanent mold casting condition. Compared to the permanent mold casting, the squeeze casting obviously reduced pore defects, refined grain size and made the SiCp distribute evenly as well as bond tightly with the Al matrix. The tensile strength, yield strength, elongation, elastic modulus and hardness of the 6082 aluminum alloy obtained with the SiCp and squeeze casting were remarkably improved, and the optimal mechanical properties were obtained with a 2 wt.% SiCp, and they increased 10.73 %, 72.7 %, 193.9 %, 23.5 % and 25.2 %, respectively, compared to those of the 6082 aluminum alloy obtained without SiCp and squeeze casting. The fracture surface of the SiCp/Al 6082 composites obtained with the squeeze casting was dense and exhibited a ductile fracture mode.

Microstructure evolution and mechanical properties of Mg-12Zn-2Y alloy containing quasicrystal phase fabricated by different casting processes

Although icosahedral quasicrystal phase (denoted as I-phase) has been verified as an outstanding reinforcing phase, the mechanical properties of quasicrystal-reinforced Mg-Zn-Y alloys fabricated by traditional casting processes are still unsatisfactory due to the serious segregation of intermetallic compounds. In this study, the microstructure and mechanical properties of Mg-12Zn-2Y alloy fabricated by different casting processes, including permanent mold casting, squeeze casting and rheo-squeeze casting with ultrasonic vibration, were systematically investigated and compared. The results show that massive, large-sized I-phase and Mg7Zn3 phase gather together in the permanent mold cast sample, while the squeeze casting process leads to the transformation of I-phase into fine lamellar morphology and the amount of Mg7Zn3 decreases. As to the rheo-squeeze casting process, when the ultrasonic vibration is exerted with power from 800 W to 1,600 W, the α-Mg grains are refined and spheroidized to a large extent, and the lamellar spacing of the eutectic structure is significantly reduced, accompanied by some tiny granular I-phase scattering in the α-Mg matrix. However, when the ultrasonic power continuously increases to 2,400 W, the eutectic structure becomes coarse. The best mechanical properties of the rheo-squeeze cast alloy are obtained when the ultrasonic power is 1,600 W. The microhardness, yield strength, ultimate tensile strength and elongation are 79.9 HV, 140 MPa, 236 MPa, and 3.25%, which are 44.1%, 26.1%, 25.5%, 132.1% respectively higher than the corresponding values of the squeeze casting sample, and are 47.6%, 44.3%, 69.8%, and 253.3% respectively higher than the corresponding values of the permanent mold casting sample.

RIO TINTO 319.2

Abstract Rio Tinto 319.2 is a heat-treatable, Al-Si-Cu casting alloy (3xx.x series). It is available in the form of ingots for remelting, for the production of sand and permanent mold castings. Alloy 319.0 exhibits very good castability and pressure tightness, moderate strength, and good high-temperature properties. It offers good strength in the as-cast condition and is often used that way. However, it is possible to increase strength considerably by heat treatment. In applications that experience high temperatures, as in engine components, it is common to employ a T5, T7, or O treatment. These treatments tend to stabilize the casting and reduced dimensional changes in the component caused by high temperatures in service. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Al-474. Producer or source: Rio Tinto Limited.

Influence of rheocasting and rare earth metals on the 3D-microstructure of ZK60 Mg-alloy measured by multiscale X-ray computed tomography

Light weighting has been a key issue to meet stringent requirements on greenhouse gas emissions. One possible way of weight reduction is the substitution of heavier components with lighter metals like Magnesium. In this work, the internal architecture of cast and hot rolled ZK60 alloys with and without addition of 1.5 wt% rare earth metals (RE) has been investigated. The alloys were produced by permanent mould indirect chill cast (PMICC), while the material with 1.5 wt% RE was manufactured by additional rheocasting (RC). A multi-resolution procedure using X-ray computed tomography (XCT) was performed to investigate the alloys in size ranges from meso- (cast blocks) to micro-scale (microstructure). The voxel resolutions used were between (115 μm)3 down to (0.8 μm)3. Morphometric parameters such as volume, volume fraction, connectivity, structure separation, structure thickness etc. were calculated to characterize the 3D-microstructure of the various alloys. The alloys showed no detectable cracks in the as-cast condition, while macroscopic defects such as clusters of high-density Zr-rich particles as well as casting pores were identified. The Zr-rich particles as well as other primary intermetallic phases tended to agglomerate at the bottom of the ingots for all investigated alloys. The addition of RE increased the homogeneity of the microstructure in terms of spatial distribution as well as the global and local interconnectivities of intermetallic phases in the PMICC alloy. RC achieved a more homogeneous distribution of Zr-rich particles. Furthermore, RC led to changes of the solidification topology and increased the distance between the higher-density phases. Hot rolling reduced the fraction of pores formed during the casting process. However, pores were not detected in the ZK60 PMICC alloys after forming, while ZK60 + 1.5 wt% RE PMICC and RC showed the presence of voids that were not completely removed by hot rolling until the thickness was reduced about 60%.

Nano-yttrium-containing precipitates of T6 heat-treated A356.2 alloy when trace yttrium (Y less than 0.100 wt%) added

To investigate the effect of yttrium (Y) on microstructure refinement and mechanical properties of aluminum alloy A356.2, the different trace contents of Y (0 wt%, 0.025 wt%, 0.050 wt%, 0.075 wt%, or 0.100 wt%) were introduced into the liquid alloy. The alloys were fabricated in a preheated permanent mold, and subsequently treated by a T6 heat treatment. The results of tensile testing indicate that the yield strength (YS), the ultimate tensile strength (UTS) and the elongation (El) of the A356.2 alloy are improved by the Y additions. The YS dependence on grain size for the test alloys follows the Hall–Petch equation, which gives $${\text{YS}} = - 354.1 + {2875}{\text{.2}}d^{ - 1/2}$$ with a correlation of R2 = 0.83. As 0.050 wt% Y is added, the optimum values of the YS, UTS and El are achieved after T6 heat treatment. The secondary phases were identified by X-ray diffraction (XRD) which mainly consisted as Si, Mg2Si and Al3Y. The scanning electron microscope (SEM) and energy-dispersive spectrometer (EDS) analyses reveal the presence of the nano-sized Al3Y particles on the surface of the Si phase. The A356.2 alloy with the Y addition is strengthened by the dendritic refinement, and the presence of the micron- and nano-sized Al3Y precipitates.

Low pressure casting effect to tensile strength of aluminium

The air in the mould cavity is pushed out by liquid metal when the liquid metal entered mould cavity. In green sand-casting process, the air passes through the pores in the mould. Permanent mould doesn’t have pores and the air released from the mould cavity only through air outlet. Low pressure on mould cavity make liquid metal easier and faster filling the mould cavity, and make casting process can be done at lower temperature, the main focus of this research is about effect of pouring temperature on the low-pressure casting process to tensile strength and porosity of the aluminium. The casting process carried out at 750, 800 and 850°C. Aluminium smelting uses electric furnace and the mould used is a metal mould with a pressure of 0.33 atm. The casting process on aluminium at low pressure (-0.33 atm) and at a temperature of 750 °C produces the highest tensile strength compared to aluminium casting at 800 and 850 °C. The increasing pouring temperature increasing porosity of aluminium is from 1.86% at 750 °C to 4.03% at 850 °C.

The effect of pouring temperatures to tensile strength and porosity of aluminium processed with vacuum casting

Pouring temperature also affects the mechanical properties of aluminium. High pouring temperature will make aluminium grains become large and a lot of gas will be trapped into the liquid metal when the metal is poured into the mould. The right temperature will prevent metal porosity and the metal does not freeze before filling the entire moulds cavity. The casting process used permanent mould. Temperature of the moulds was 150 °C and the pressure 0.35 atm (absolute pressure). Pouring temperature were 750, 800 and 850 °C. The increasing pouring temperature reduce the tensile strength and specific density of aluminium. Pouring temperature aluminium in vacuum casting system at 750 °C produce the highest tensile strength (130.26 MPa). The specific density of the aluminium is 2.65 g/cm3

Analysis of tensile strength, microstructure, and fractograph of Al-Si with snail shell powder as reinforce agent

This research aimed to increase the mechanical property of Al-Si alloy by adding snail shell powder reinforcement using the stir casting method. This research used 1 minute, 2 minutes, and 3 minutes variations of stirring time. The snail shell powder percentage in this research was 0.05 wt% from the total 1.5 kg Al-Si alloy. The stir casting method was performed by melting the Al-Si in the furnace then was stirred at 500 rpm speed in 850°C temperature before sprinkled with snail shell powder. After the stir casting process, the Al-Si alloy was poured into permanent cylindric mould according to the tensile test specimen. The specimens then tested with the mechanical test to find the tensile strength and microstructure. The results showed increases of the mechanical property with the best result was found in the specimen with a stirring time of 3 minutes with the value of 21.04 kg/mm2.

Regolith as substitute mold material for aluminum casting on the Moon

ESA, NASA, and other space institutions are planning the return to the Moon. In the next decades, a human outpost on the lunar surface is going to be established to extend the opportunities for science and economy. For this project, new materials, methods, and processes based on In-Situ Resource Utilization (ISRU) are needed. One aspect is the casting of metals to produce tools, construction elements, or infrastructure, which are to frail or too large to be transported with a rocket. Earth-based manufacturing relies on sand-casting or permanent mold casting processes. These could be adapted for Moon manufacturing with lunar regolith. Regolith can be shaped and/or sintered to produce a mold similar to sand-casting or permanent mold casting. This paper presents results from first experiments carried out by TU Braunschweig and Orbit Recycling with aluminum, Al-alloys and the regolith simulant TUBS-M. It is shown that it is possible to cast a wide range of aluminum parts using lunar regolith. Using a permanent mold, it was possible to achieve multiple casts from one mold. Thus, new ISRU based adapted processes for lunar manufacturing could be possible.

Mathematical Modelling of Vickers Hardness of Sn-9Zn-Cu Solder Alloys Using an Artificial Neural Network

An artificial neural network (ANN) model was used for the simulation and prediction of the mechanical properties of Sn-9Zn-Cu solder alloys. Sn-9Zn-Cu solder alloys containing different Cu contents (0, 1, 2, 3, 4 and 5 wt%) were successfully prepared by permanent mold casting. The specimens were heated in a protective argon atmosphere at 433 K for 24 h, followed by water quenching at 298 K. Finally, the heat-treated samples were aged at 373 K for different time intervals (ta = 2, 4, 8, 16 and 32 h), followed by water quenching at 298 K. The phases present in the current alloys were detected by X-ray diffraction analysis. For morphological characterization, a scanning electron microscope operated at 20 kV was tilized. The mechanical properties of the samples were studied using hardness measurements. The variations in the hardness data with increasing aging time were determined based on the structural transformations that take place in the alloys. The ANN model was applied to the hardness measurements to simulate and predict the Vickers hardness of Sn-Zn-Cu alloys with mean square error values equal 9.55E-06 and 9.44E-06 for training and validation data respectively after 281 epochs. The simulated and predicted results were consistent with the experimental results.

Application of Niyama criterion for predicting of shrinkage porosity of shaped castings

Method for determining of the critical value of the Niyama criterion based on computational experiment is developed. It is found that the critical value of the Niyama criterion depends on the alloy cooling conditions and therefore is applicable only to the given technological process. The critical values of the Niyama criterion for casting s made of ML10 and 14Kh17N2L alloys obtained in permanent metal moulds and in moulds of coldhardening mixtures are determined. The obtained results are confirmed on shaped casting.

Analyzing the Cooling Rate and Its Effect on Distribution of Pattern and Size of the Titanium Diboride Particles Formed

In this work, we synthesize Al/TiB2 metal matrix composites (MMC) based on the effect of cooling rate in the melt while pouring into the permanent mold condition. The objective of this paper is to achieve the desired distribution pattern and increased TiB2 particles’ size in the Al/TiB2 MMC ingot. Two halide salts, viz., potassium hexafluorotitanate (K2TiF6) and potassium tetrafluoroborate (KBF4), are procured and measured. The two salts were mixed with the aluminium melt in the crucible, and it is stirred manually with help of a graphite rod. Because of the exothermic reaction, the melt reacts very quickly and that is what dropped the salts slowly. The salt particles were synthesized because of the exothermic reaction, and it will allow the particles to grow. The size and distribution of particles differ at different place in the MMC. An FEA tool ProCAST was used to analyze the cooling rate of the melt, and SEM is used to study the microstructure of the ingot at different places. The microstructures helped to identify the size of reinforcement in the MMC. The TiB2 particles are distributed more at this location at 810°C, and the TiB2 particles formed various clusters in this zone as 70%–80%. Also, the tribological characteristics are analyzed with the help of the results.

DURA-BAR G2A

Abstract Dura-Bar G2A is a gray cast iron that is used for the production of continuous cast products. It contains Type VII, Distribution D flake graphite in a predominantly pearlitic matrix and is typically used in permanent mold applications requiring a combination of optimal strength and wear resistance, and superior surface finish. This datasheet provides information on composition, physical properties, microstructure, hardness, and tensile properties as well as fatigue. It also includes information on heat treating. Filing Code: CI-77. Producer or source: Charter Dura-Bar, Inc.

Arc welding renovation of permanent steel molds

Arc welding renovation of permanent steel molds

Interfacial Heat Transfer Coefficient in Unidirectional Permanent Mold Casting: Modeling and Inverse Estimation

The thermal control of the permanent mold casting process is highly dependent on the Interfacial Heat Transfer Coefficient (IHTC). Based on that, many works proposed several models in order to estimate its behavior. This work intends to study three IHTC models present in the literature, as well as to propose and analyse two new models. The proposed models are based on two distinct methodologies: thermal resistance method and analytical comparison to the thermal gradient formulation at the metal/mold interface. All these models will be analysed in terms of their ability to reduce the error between the simulated and experimental thermal profiles by using an inverse method and verifying their respective parameter sensitivity based on the relative sensitivity coefficient. It is observed that the exponential formulation model, proposed in this paper, is able to reduce the numerical/experimental error more efficiently than the others methods in all three hypoeutectic alloys of the Al-Si system considered.

Study of kinetics of the supersaturated solid solution decomposition in alloys of the Al – Mg system with transition elements addition

The objective of the study is to determine kinetics of L12 structure type particles precipitation in Al – Mg system aluminum alloys, containing scandium and zirconium. The article addresses microstructure evolution of scandium containing alloys, including two-component alloy and Al – Mg system alloys, containing multiple components, i.e., 1565ch alloy (Al – Mg – Mn – Zn – Zr system) and 01570 alloy (Al – Mg – Mn – Sc – Zr system). The samples were produced by casting in water chilled copper permanent mold. Analysis of the samples, representing various alloys, including 99.95% pure aluminum, confirmed quantitative data of solutes effect on electrical resistance. The optimal homogenization modes, enabling max alloying components dissolution in aluminum matrix, were established for the studied alloys. After that the samples were subjected to heterogenization annealing in the temperature range from 250 oC to 450 oC, with soaking time ranging from 1 to 106 s. C-curves of supersaturated solid solution decomposition were plotted based on correlation of samples electrical resistance in max saturated solution and after annealing under different modes; it was demonstrated, that decomposition curves of the alloys, containing 0.2 and more scandium, have two peaks, at 300 oC and at 425 oC. The obtained data are approximated by power functions (min determination coefficient R2 is 0.97), which are helpful for such alloys thermomechanical treatment modelling. It is demonstrated, that during cast samples heat treatment at the temperature above 350 oC decomposition of alloys, containing 0.2% and more scandium, is associated with secondary crystallization, and decomposition product distribution is fan-shaped, confirming the theory of discontinuous decomposition, observed by other researchers in similar alloys. The size of L12 structure particles, generated during discontinuous decomposition, ranged from 50 to 270 nm, which is significantly different from the optimal values of 40–50 nm.The study was supported by a grant from the Russian Science Foundation, project 18-79-10099.

Interfacial microstructures and properties of hyper-eutectic Al–21Si / hypo-eutectic Al–7.5Si bimetallic material fabricated by liquid–liquid casting route

Abstract. The bimetal casting process using the liquid–liquid technique was developed to produce a high-quality hyper-eutectic Al–21Si / hypo-eutectic Al–7.5Si alloy bimetal material. Microstructure and microhardness were investigated as a function of the time interval between pouring hypo-eutectic and hyper-eutectic alloys. A bimetal material was successfully fabricated using a liquid–liquid casting technique with a 10 s time interval in a permanent mould casting. A unique structure comprised of hyper-eutectic Al–21Si, hypo-eutectic Al–7.5Si and a eutectic interface of 70 µm thickness was obtained. This structure totally differs from that obtained using a higher time interval above 10 s that showed an imperfect interface bond due to the shrinkage cavity and formation of oxides. The hardness variation from the upper zone of 117.5 HV to the lower zone of 76 HV corresponded to the variation in Si and the content of other alloying elements. The proposed total solidification time control method is a promising approach for the successful fabrication of liquid–liquid bimetal material.

Development of an Instrumented Test Tool for the Determination of Heat Transfer Coefficients for Die Casting Applications

In the case of casting processes with permanent molds, there is still a relatively pronounced lack of knowledge regarding the locally prevailing heat transfer between casts and mold. This in turn results in an insufficient knowledge of the microstructure and the associated material properties in the areas of the casting component close to the surface. Therefore, this work deals with the design and evaluation of a test tool with an integrated sensor system for temperature measurements, which was applied to obtain a time-dependent heat transfer coefficient (HTC) during casting solidification. For this purpose, the setup, design and computational approach are described first. Special attention is paid to the qualification of the multi-depth sensor and the calculation method. For the calculations, an inverse estimation method (nonlinear sequential function) was used to obtain the HTC profiles from the collected data. The developed sensor technology was used in a test mold to verify the usability of the sensor technology and the plausibility of the obtained calculation results under real casting conditions and associated temperature loads. Both the experimental temperature profiles and the HTC profiles showed that, in the evaluated casting series, the peak values determined were close to each other and reached values between 6000 W/(m2·K) and 8000 W/(m2·K) during solidification.