Mechanical Properties Of Castings Research Articles

Microstructure and mechanical properties of cast, eutectic Al-Ce-Ni-Mn-Sc-Zr alloys with multiple strengthening mechanisms

The effects of Ni additions on microstructure and microhardness of near-eutectic Al-9Ce-xNi-0.75Mn-0.18Sc-0.12Zr (x = 2.5, 3.2, and 3.9 wt.%) alloys are investigated for various cooling rates. The as-cast microstructure consists of fine, micron-scale Al11Ce3 and Ni-rich phases formed during eutectic solidification. Two Ni-rich phases are observed: (i) Al27Ce3Ni6 at higher Ni contents and slower solidification rates, and (ii) Al9(Ni,Mn,Fe)2 at lower Ni contents and faster solidification rates. While these Ni-containing alloys have higher microhardness than a Ni-free control alloy, varying the Ni concentration in the 2.5–3.9 wt.% range does not significantly affect the microhardness, indicative of competing strengthening and weakening effects from adding Ni. The alloy with intermediate Ni content (3.2 wt.%) is selected for further microstructural and mechanical characterization. It contains four coarsening-resistant strengthening constituents: (i) micron-scale Al11Ce3 and (ii) Al27Ce3Ni6 or Al9(Ni,Mn,Fe)2 platelets, all formed during eutectic solidification, (iii) L12-Al3(Sc,Zr) nanoprecipitates formed on aging, and (iv) Mn atoms in solid solution in the α-Al matrix. The combined strengthening mechanisms impart high strength at ambient and elevated temperatures, as measured by microhardness (as a function of aging time), by compression and tensile experiments, and by compressive creep measurements. Alloys previously reported in the literature - with various combinations of one, two or three of these four strengthening phases - show lower hardness and creep resistance, indicating that cumulative strengthening can be achieved when combining mechanisms; the present alloy containing all four phases shows a remarkably high creep threshold stress of 62 MPa at 300 °C.

Comparison of microstructure, damping capacity, and mechanical properties of cast and deformation processed Fe17Mn alloys

There were few works on cast FeMn damping alloys although many studies have been conducted on deformation processed (DP) counterparts. In this study, we investigated the differences in damping and mechanical properties of as-cast and as-DP Fe17Mn alloys and the effect of solution treatment at 1050℃ (ST) on their properties. The as-cast Fe17Mn alloy demonstrated a higher damping capacity but lower strength than the as-DP Fe17Mn counterpart. As much as 18 % of the BCC phase was distributed as dendrite in the Mn-depleted region of the as-cast Fe17Mn alloy. The DP Fe17Mn alloy inherited some BCC phase with less than 1 % content formed during the casting. The ST further improved the damping capacity and plasticity but decreased the strength in both the cast and DP Fe17Mn alloys. After the ST, the cast Fe17Mn alloy also showed good mechanical properties, with tensile strength up to 645 MPa and fracture up to 40 %. Our results shed light on the potential application of cast Fe17Mn alloy in mechanical components.

Effects of Fe content on the 3D morphology of Fe-rich phases and mechanical properties of cast Al-Mg-Si alloy

Fe is a common impurity element in recycled aluminum scraps, and adjusting Fe content can effectively promote the effective utilization of recycled aluminum. In this study, Al-Mg-Si-Mn-Fe alloys with different Fe contents were prepared by adding various percentage of aluminum scraps. Synchrotron X-ray tomography technology was used to study the morphological evolution of Fe-rich phases and corresponding effect on mechanical properties of studied alloys. The results showed that as the Fe content increased, the 3D morphology of Fe-rich phases changed from fine Chinese-script and needle-like shapes to coarse Chinese-script structure. Their 3D morphology was mainly composed of thin platelets and curved branches. The increase in Fe content did not significantly change the 3D structure of Fe-rich phases, but increased the volume fraction of large Fe-rich phases. When the Fe content reached 0.35 %, the maximum volume and the number of branches of individual phases increased by 182.9 % and 142.2 %, respectively, compared with the 0.2Fe alloy. With the increase of Fe content, the ductility of alloys gradually decreased, especially when the Fe content exceeded 0.25 %. The Fe content had a small effect on the liquidus temperature of alloys, but it changed the initial formation temperature and type of Fe-rich phases. When the Fe content exceeded 0.32 %, it promoted the formation of β-Fe phase, which may be the main reason for the significant decrease in ductility of studied alloys with higher Fe content.

CHANGES IN THE STRUCTURE AND PROPERTIES OF ALUMINIUM ALLOYS WHEN MODIFIED WITH POWDER COMPOSITIONS

Purpose. To determine the effect of modification with powder compositions on the structure and mechanical properties of cast and deformed aluminium alloys. Research methods. Metallographic analysis, stereometric metallography, testing of strength and plastic properties of cast alloys AL4, AL4C of the Al-Si system and deformed alloys 1545 of the Al-Mg-Sc system, 2219 of the Al-Cu-Mn system in their original and modified state. Results. Meltings of AL4, AL4C, 1545, 2219 alloys were carried out in the initial state and with melt treatment with a complex nano-disperse modifier of magnesium silicide Mg2Si and silicon carbide SiC with a particle size of 50...100 nm. The optimal content of Mg2Si+SiC (0.10%) for increasing σ0.2 of aluminium alloys was determined. A 1.6-fold reduction in the grain structure of cast alloys was achieved. The dependence of the particle size and the amount of the modifier on the mechanical properties of the alloys was established. In industrial experiments, the most effective particle size of Mg2Si+SiC was established for increasing σ0.2 of AL4, AL4C alloy from 115 to 260 MPa in the as-cast state. The increase in the strength properties of the modified alloys is 44 % compared to the original state. Scientific novelty. Further development, insight into the influence of melt modification on the parameters of the structure and properties of aluminium alloys was obtained. The use of nanodispersed complex modifier Mg2Si+SiС with a particle size of 50...100 nm is proposed. It has been confirmed that the use of complex nanodisperse modifiers allows you to actively influence the structure and mechanical properties of aluminium alloys. Practical value. It has been experimentally proven that the rational amount of the introduced complex modifier is 0.10% of the mass of the melt. A significant grinding of the grain structure and an increase in the strength properties of cast and deformed aluminium alloys were achieved as a result of the modification.

Effect Mechanism of Sc Addition and T6 Heat Treatment on Precipitated Phase and Mechanical Properties of Al‐Cu‐Mn Alloy

The microstructure and mechanical properties of cast Al‐Cu‐Mn alloy influenced by various Sc additions (viz. 0.1, 0.2, 0.3, 0.4, and 0.5 wt%) are investigated. It is found that the grain size of α‐Al and the area proportion of the second phase are decreased with the addition of Sc. In addition, the morphology of the precipitated phase in Al‐Cu‐Mn alloy also evolves at different stages, and the solidification temperature range and initial enthalpy change of the alloy are changed, resulting in the formation of a variety of second‐phase containing Sc. Owing to the grain refinement and precipitation strengthening effects, the hardness of as‐cast alloys is better than T6 alloys. Moreover, it is observed that when the Sc content is 0.3%, the mechanical properties of the as‐cast Al‐Cu‐Mn alloy are the minimum, and the Al‐Cu‐Mn alloys after T6 heat treatment are the maximum. These results confirm that the mechanical properties improvement effect of the as‐cast Al‐Cu‐Mn alloy is greater than that of the T6 heat treatment Al‐Cu‐Mn alloy with the addition of Sc. Meanwhile, the Orowan strengthening mechanism is found to have lost its dominant position.

Microstructure and Mechanical Properties of Cast Al-15Mg2Si-8Si-Based Alloy with Various Cr-Sb Ratio Addition

Microstructure and Mechanical Properties of Cast Al-15Mg2Si-8Si-Based Alloy with Various Cr-Sb Ratio Addition

Comparison of wear and mechanical properties of cast and 3D printed CuSn10 bronze alloy

Abstract This paper aims to provide a comparison between properties of CuSn10 bronze alloy produced by two methods: FDM (fused deposition modelling) and casting. Wear behavior, mechanical performance and microstructure of CuSn10 alloy produced by FDM and casting methods were determined and compared. 3D printed parts were sintered at 875 °C for 5 h and casting was done at 1200 °C. The amount of porosity was determined by the metallographic cross-sectional examination. Vicker’s hardness, wear and tensile properties of samples were determined. As a result, the porosity value of the CuSn10 alloy produced by the FDM technique was determined as 5.07 ± 0.53%. Tensile strength values were 233.75 ± 18.48 MPa and 349.04 ± 5.10 MPa for CuSn10 alloys produced by FDM and casting methods respectively. While adhesive wear occurs in both production methods, it was observed that the FDM method reduced the wear resistance.

Effect of Ti content on microstructures and mechanical properties of cast Al-2Li-2Cu-0.5Mg alloy

Effect of Ti content on microstructures and mechanical properties of cast Al-2Li-2Cu-0.5Mg alloy

Investigations on microstructure and mechanical properties of cast Mg-Gd-Y-Zn-Zr-Nd alloy

Different solution treatments were carried out on the semi-continuously cast Mg-9.55Gd-2.27Y-1.28Zn-0.55Zr-0.11Nd (wt.%) alloy at temperatures of 480 °C, 500 °C, and 520 °C. It was found that the different solution treatment temperatures led to different phase constitutions of the alloy. The Mg3RE-type eutectic phases transform into long period stacking order (LPSO) phases with various morphologies after solution treatment. Increasing the solution temperature resulted in larger grain size, greater number of lamellar LPSO phases, and segregation of Zr element. Block LPSO phases also shifted to rod LPSO phase. After ageing treatment, the special spatial structure consisting of prismatic β′ precipitates, basal γ′ precipitates, and lamellar LPSO phases hindered dislocation movement effectively, leading to high strength.However, the accumulation of massive dislocations promoted the premature formation of cracks at the grain boundary and LPSO/Mg matrix interface, resulting in a rapid decrease in ductility of the alloy. After solution treatment at 480 °C for 12 h and aged at 200 °C for 48 h, the Mg-9.55Gd-2.27Y-1.28Zn-0.55Zr-0.11Nd alloy exhibited favorable comprehensive mechanical properties at room temperature: ultimate tensile strength (UTS) of 383 MPa, tensile yield strength (TYS) of 269 MPa, and fracture elongation (EL) of 5.1%.

Microstructure and Mechanical Properties of Cast Al-Si-Cu-Mg-Ni-Cr Alloys: Effects of Time and Temperature on Two-Stage Solution Treatment and Ageing

Ameliorating the high-temperature performance of cast Al-Si alloys used as engine components is essential. The effects of different T6 heat-treatment processes on the microstructure and mechanical properties of cast Al-Si-Cu-Mg-Ni-Cr alloys were investigated in the present study. The results demonstrate that, under the optimal solution treatment conditions of 500 °C for 2 h and 540 °C for 4 h, the T-Al9FeNi phase was present in the alloy, and the roundness of primary Si and the aspect ratio of eutectic Si in the alloy reached valley values of 1.46 and 2.56, respectively. With increasing ageing time at 180 °C, the tensile strength significantly improved, while the microhardness first increased and then decreased. When the ageing time was 4 h, microhardness reached a peak value of 155.82 HV. The fracture characteristics changed from quasi-cleavage to the coexistence of quasi-cleavage and dimples. After heat treatment, the high-temperature tensile properties of the alloy improved, which is a significant advantage compared to the as-cast alloy. The stable Al3Ni and Al9FeNi phases inhibited the cracking of the alloy at 350 °C.

The effect of overheating of aluminum melts on the mechanical properties of castings

The article investigates the effect of overheating of aluminum melts on the mechanical properties of castings. The authors use the data of chemical analysis and study the microstructure of castings. The rationale for the relevance of the topic is based on a review of modern scientific and technical developments, as well as a review of scientific periodicals in the field of metallurgical processes over the past five decades. It is noted that at present a large amount of experimental data has been accumulated, which indicates that metal melts are complex dynamic systems. A significant effect of the structural state of the initial melt on the formation of the structure and properties of ingots obtained from this melt has been established. In this work, the effect of heat treatment of the melt was studied on a high-strength cast aluminum-magnesium alloy with a wide crystallization range (433 K). In order to obtain dense castings, pouring was carried out in a bottomless mold with a slotted gating-feeding system, installed on the surface of a copper water-cooled box. This provided directional solidification of the alloy. Experimental results are presented, chemical analysis data are processed, and the microstructure of castings is studied.

Effect of vibration casting on the properties and microstructure of aluminium alloy castings

This research focuses on investigating the impact of mechanical vibration on the solidification process. Previous studies have indicated that solidification plays a crucial role in enhancing the mechanical properties of materials. By incorporating mechanical vibration technology into the solidification process, the quality of castings can be improved by achieving a more uniform microstructure and reducing grain size. In today’s industrial landscape, striving for excellence involves minimising casting defects to zero and enhancing mechanical characteristics. To comprehend the enhancement in microstructure and mechanical properties of castings, this experimental study examines the influence of mechanical mould vibration on the solidification of A356 alloy. The casting process involves a frequency of 50[Formula: see text]Hz. To evaluate the effect of vibration during casting, a comparison is made between a casting without mould vibration and its corresponding mechanical properties. The experimental results clearly demonstrate that employing a vibrating mould during casting leads to grain refinement and a significant improvement in hardness when compared to castings produced without the utilisation of a vibrating mould.

Assessment of the effect of small additions of some rare earth elements on the structure and mechanical properties of castings from hypereutectic chromium white irons

<abstract> <p>Article considers the influence of additions of rare earth elements such as Sm, La, Ce, Nd, and Y on the structure and properties of hypereutectic high-chromium white cast iron of grade G-X300CrMo27-2. To obtain an increased content of carbides in the studied cast iron samples, the carbon content was 3.75–3.9 and 4.1–4.2 wt%. The amount of rare earth elements additives added to the melt is 0.2% by weight. Data were obtained on the effect of overheating and cooling rate in the crystallization interval on the effect of rare earth additives, the structure and properties of white cast iron castings are given. According to the results of the microprobe analysis, it was shown that, under the chosen crystallization conditions, Sm, La, and Ce can form solid solutions with primary and eutectic carbides (FeCr)<sub>7</sub>C<sub>3</sub>. La and Ce form solid solutions with austenite. Nd and Y do not dissolve in iron chromium phases. All listed rare earth elements form phosphides and oxyphosphides. Experimental data are presented on the effect of rare earth elements on the size of primary (FeCr)<sub>7</sub>C<sub>3</sub> carbides and a hypothesis is proposed on the effect of rare earth elements on the crystallization process of hypereutectic chromium white cast irons. Experimental data are presented on the effect of REE additives on the microhardness of phases, hardness, strength, and resistance to abrasive wear of cast iron castings. It was found that the introduction of these additives into hypereutectic chromium white cast iron does not contribute to the modification of the structure and leads to an increase in the size of primary crystals, as well as a decrease in their mechanical properties. However, the addition of Y increases the abrasive wear resistance, but reduces the strength of castings made from such white cast iron.</p> </abstract>

Effect of double-layer-shell sand mold on the residual stress of casting and itself crack tendency

Controlling the solidification of metals is the most essential to prevent defects and realize required quality and mechanical properties of castings. However, the conventional sand mold structure is generally dense and thick, which makes it difficult to accurately control the solidification process of castings. The hollow sand molds prepared by 3D printing technology provide the possibility to adopt measures to control the cooling of castings, but the crack on the mold itself is a new problem. Here, a kind of double-layer-shell structure of hollow sand mold is designed. It is proved that it can effectively reduce the crack tendency of the hollow sand mold, the residual stress of the casting decreases as well. Both experiment and numerical simulation results unveil the mechanism.

Evaluation of the Influence of Process Parameters on the Mechanical Properties of Castings during High Pressure Die Casting

The article is devoted to the influence of mold filling parameters by the HPDC - High Pressure Die Casting method on the mechanical and structural properties of castings intended for technology and mechanization means in forestry. Three groups of AlSi10MnMg alloy samples were formed for the experiment. Three different settings of mold cavity filling parameters were chosen. Two castings were made from each setting. Two samples were taken from two places on the casts. Thus, 12 pieces of samples were used for the experiment. An analysis of their mechanical properties was performed using a static tensile test. tensile strength, yield strength and ductility were evaluated. The microstructure was evaluated by light optical microscopy. The influence of process parameters on the quality of the casting was monitored from the point of view of the occurrence of errors, defects and the method and size of the exclusion of structural phases. The experimental results showed that the best results were obtained when the process parameters of the first group of samples were set. Their values are the closest to the customer's requirements.

Synergistic Effects of La and Y on the Microstructure and Mechanical Properties of Cast Al-Si-Cu Alloys.

The effects of La and Y on the microstructure and mechanical properties of cast Al-Si-Cu alloys were investigated by X-ray diffractometer (XRD), optical microscope (OM), and scanning electron microscope (SEM). The results indicated that the addition of La and Y had a great effect on the refinement of α-Al grains, the modification of eutectic Si phase, and the reduction of β-Al5FeSi length in Al-Si-Cu alloys. The A380 + 0.6 wt.% La/Y alloy exhibited the best microstructure and mechanical properties. The UTS and EI of the A380 + 0.6 wt.% La/Y alloy were 215.3 MPa and 5.1%, which were 22.9% and 37.8% higher than those of the matrix alloy, respectively. In addition, neither Al11La3 nor Al3Y generated by the addition of La and Y could not serve as the nucleation core of α-Al grains, so the grain refinement of α-Al originated from the growth limitation and constitutional supercooling. Since La and Y promote twinning generation and constitutional supercooling, the eutectic Si phase also changed from stripe-like to short fibrous or even granular and was significantly refined. Furthermore, thermodynamic calculations indicated that the Al11La3 phase was formed first and the Al3Y phase was generated on the Al11La3 phase.

Carbon‐based conductive rubber composite for 3D printed flexible strain sensors

AbstractPolymeric‐based flexible electronic devices are in high demand due to its wide range of applications. Natural rubber (NR) shows a great potential as matrix phase for flexible conductive polymer composites with its high elasticity and fatigue resistance. In this study, a new 3D printable conductive NR (CNR) composite was developed for strain sensor applications. Different contents of conductive carbon black (CCB) were mixed with NR latex to investigate the effect of the filler content on electrical and mechanical properties of the composites. The best‐known CNR composite with the CCB content of 12 phr was selected in order to produce the feedstock for the stereolithography process (SLA). The morphological, electrical, and mechanical properties of cast and 3D‐printed samples were investigated and compared. Although the 3D‐printed CNR sample had slightly lower conductivity than the cast one, it possessed comparable tensile strength and elongation at break, with values of 12.4 MPa and 703%, respectively. In addition, electrical responses of the CNR samples were investigated to demonstrate the electromechanical property of the material as a strain sensor. The 3D‐printed CNR sample exhibited the highest electromechanical sensitivity with a gauge factor (GF) of 361.4 (ε = 210%–300%) and showed good repeatability for 500 cycles. In conclusion, the development of this 3D printable functional material with great sensing capability will pave the way for innovative designs of personalized sensing textiles and other smart wearable devices.

Implications of carbon content for the processing, stability, and mechanical properties of cast and wrought Ni-based superalloy Nimonic 105

As the temperature and pressure requirements in land-based turbines for power generation increase, the shift towards more advanced alloys, e.g., Ni-based superalloys, requires improved understanding of their long-term stability and mechanical properties. Additionally, the larger size of the components also presents fabrication and cost-reduction problems. In this study, we investigated Nimonic 105 as a potential rotor material at two carbon content levels – the commonly used maximum of the alloy specification and a lower carbon content variant. Reducing the carbon content presented fabrication challenges, resulting in surface crack formation during hot working. Additionally, a lower M6C carbide fraction was present after fabrication/solutioning, leading to a significantly larger grain size. After the standard aging treatment, similar γ′ populations formed in the two variants, however the M6C carbides in the high-carbon variant already started transforming to intergranular M23C6. Although we did not observe a noticeable effect on the tensile properties of the two variants, the lower carbon content alloy possessed a superior creep property – mainly due to the larger grain size as the microstructural stability was inferior. Upon prolonged thermal exposure, the M6C carbides in the low-carbon variant further decomposed to intergranular and intragranular σ and μ precipitates, as opposed to mainly M23C6 as in the high-carbon variant.

Microstructure and mechanical properties of cast Al-Ce-Sc-Zr-(Er) alloys strengthened by Al11Ce3 micro-platelets and L12 Al3(Sc,Zr,Er) nano-precipitates

The microstructure and mechanical properties of two die-cast hypoeutectic Al-Ce-based alloys modified with Sc, Zr and Er micro-additions – Al-1.5Ce-0.14Sc-0.03Zr with high Sc content and Al-1.4Ce-0.02Sc-0.06Zr-0.003Er (at%) with low Sc content – are studied, with focus on the two strengthening phases: micron-scale Al11Ce3 platelets formed on solidification and L12 Al3(Sc,Zr,Er) nanoprecipitates formed during aging. The evolution of microstructure and microhardness upon isothermal aging at 350 and 400 °C, and the creep resistance at 300 °C, are studied and compared to alloys containing only one of these strengthening phases. The Al11Ce3 and L12 phases form mostly independently of each other, except in the low-Sc alloy where scavenging of Er and Si by Al11Ce3 on solidification reduces the kinetics of precipitation and number density of the L12 precipitates formed on subsequent aging. The two strengthening phases, while mostly independent of each other chemically, interact synergistically in terms of strengthening. At ambient temperature, the hardness of the Al11Ce3- and L12-strengthened alloys is higher than that of similar alloys containing only one strengthening phase. At 300 °C, the creep strain rate is reduced by as much as five orders of magnitude in the Al11Ce3- and L12-strengthened alloys compared to alloys containing only L12 precipitates. This improvement in both room and elevated-temperature mechanical properties is modeled through a combination of load transfer from the Al11Ce3 micro-platelets, and precipitation strengthening from the Al3(Sc,Zr,Er) nanoprecipitates.

Devising resource-saving technologies for the production of casting from magnesium alloys using waste of metallurgical enterprises

Based on the study of the chemical composition and analysis of the physicochemical properties of waste from a number of metallurgical enterprises in the Zaporizhzhya region, the possibility of using waste as charge materials for the production of magnesium-based alloys has been established. The possibility of using solid salt chlorinator melt (SCM) from ZTMC as a flux in the smelting of magnesium alloy instead of the flux VI-2 has been studied; its effect on the structure and mechanical properties of casting was investigated. The technological possibility of using these chloride wastes in the smelting of the ML5 alloy is shown. It was established that the use of SCM as a flux in the smelting of magnesium alloy contributes to the grinding of the structure and improvement of the mechanical properties of the metal of experimental smelting. The possibility of modification of foundry magnesium alloy with graphite powder (GP), which is the waste from JSC "Ukrgrafit", is investigated. It is shown that the optimal GP additive in the volume of 0.05...0.3 % contributes to the grinding of metal grain and increases its strength characteristics due to additional strengthening of both solid solution and eutectoid. It is established that carbon changes the parameters of eutectic transformation, as a result of which, with an increase in its concentration in the alloy, the volume of eutectoid of type δ+γ (Mg4Al3) decreases markedly. Testing the proposed waste for the smelting of the M5 alloy showed that no changes in melting technology are required while the environmental safety of the devised technological process meets the established standards; their quality was improved while increasing the strength limit by 25 %, and plasticity by 30 %. At the same time, the use of waste in the smelting of magnesium alloys can reduce costs in its production, and improve the environmental situation due to the fact that waste is not disposed of at landfills but reused in metallurgical industries