Solid Liquid Compound Casting Research Articles

Effects of mechanical vibration on filling and solidification behavior, microstructure and performance of Al/Mg bimetal by lost foam compound casting

Al/Mg bimetal was prepared by lost foam solid-liquid compound casting, and the effects of mechanical vibration on the filling and solidification behavior, microstructure and performance of the bimetal were investigated. Results show that the mechanical vibration has a remarkable influence on the filling and solidification processes. It is found that after mechanical vibration, the filling rate increases and the filling rate at different times is more uniform than that without vibration. In addition, the mechanical vibration also increases the wettability between liquid AZ91D and A356 inlays. The mechanical vibration reduces the horizontal and vertical temperature gradient of the casting and makes the temperature distribution of the whole casting more uniform. Compared to the Al/Mg bimetal without vibration, the shear strength is improved by 39.76% after the mechanical vibration is applied, due to the decrease of the inclusions and Al12Mg17 dendrites, and the refinement and uniform distribution of the Mg2Si particles in the interface of the Al/Mg bimetal.

Interfacial Microstructure and Shear Strength Improvements of Babbitt–Steel Bimetal Composites Using Sn–Bi Interlayer via Liquid–Solid Casting

To enhance the performance of Babbitt–steel bimetallic composites, bismuth (Bi) was incorporated into the Tin (Sn)-interlayer. Babbitt–steel bimetallic composites were created using the liquid–solid compound casting method in this study. Sn–Bi interlayer alloys with varying levels of Bi (1, 2, 3, and 4 wt.%) were created. The Babbitt-steel bimetallic composite’s bonding strength and interfacial microstructure were examined in relation to Sn-Bi interlayer alloys. The structure of the interface layer at the Babbitt–steel interface’s edge and center are significantly altered when Bi is added to the Sn interlayer. The relatively higher cooling rate near the edge led to the formation of clear unsolved Sn/Sn–Bi interlayers. Otherwise, the Sn–Bi interlayers in the middle were completely dissolved. By increasing the amount of Bi in the Sn–Bi interlayer alloy, the interfacial hardness of Babbitt-steel bimetallic composites increases by increasing Bi content in Sn–Bi interlayer alloy. Babbitt-steel bimetal composites’ shear strength increased to 28.27 MPa by adding Bi to the Sn interlayer using 1 wt.% alloying, with a 10.3% increase when compared with the reference pure Sn interlayer. Future research that aims to improve the production of Babbitt-steel bimetallic composites with high-quality and long-lasting bi-metal bonding ought to take into consideration the ideal pouring temperature, the preheating of the mold, and the addition of a minor amount of Bi (Bi ≤ 1) to the Sn-interlayer.

Effect of HEA/Al composite interlayer on microstructure and mechanical property of Ti/Mg bimetal composite by solid-liquid compound casting

In this study, HEA/Al composite interlayer was used to fabricate Ti/Mg bimetal composites by solid-liquid compound casting process. The Al layer was prepared on the surface of TC4 alloy by hot dipping, and the FeCoNiCr HEA layer was prepared by magnetron sputtering onto the Al layer. The influence of the HEA layer thickness and pouring temperature on interface evolution was investigated based on SEM observation and thermodynamic analysis. Results indicate that the sluggish diffusion effect of HEA can effectively inhibit the interfacial diffusion between Al and Mg, which is conducive to the formation of solid solution, especially when the thickness of HEA is 800 nm. With the increase of casting temperature from 720 °C to 730 °C, 740°C, and 750 °C, α-Al(Mg), α-Al(Mg)+Al3Mg2, Al3Mg2+Al12Mg17, and Al12Mg17+δ-Mg are formed at the interface of Ti/Mg bimetal, respectively. When the thickness of the HEA layer is 800 nm and the pouring temperature is 720 °C, the bonding strength of the Ti/Mg bimetal can reach the maximum of 93.6 MPa.

Zinc-based alloy rapid tooling for sheet metal forming reinforced by SLM steel inlays

Among the existing rapid and economical sheet metal–forming technologies, stamping with a press using soft tools, especially low-melting-point alloy dies, is one of the few methods that can meet the precision requirements in industrial fields such as automobile manufacturing. However, the usability of the method is limited by the low strength of the soft base. The current study proposes a new structure of zinc-based alloy dies for sheet metal forming, where the weak features of the die blocks, such as protruding edges, are reinforced by selective laser melting steel inlays imbedded during solid–liquid compound casting. A technical route for fabricating the new tools was developed, and a W-shaped part was formed using an SUS304 sheet with a thickness of 0.32 mm and an Al6061 sheet with a thickness of 1 mm to validate the concept. The experiment and simulation results proved that clearer localized features, such as a smaller radius, can be formed on the workpiece with the reinforcement of steel inlays, while the springback is smaller and the abrasion resistance of the tool is higher. This method can improve the forming quality and durability of traditional soft tools in a convenient and affordable way.

Effect of Q235 Hot-Dip Galvanized and Post-Casting T6 Heat Treatment on Microstructure and Mechanical Properties of Interfacial between AZ63 and Q235 by Solid-Liquid Compound Casting

AZ63 sacrificial anode is widely used to protect buried metal pipelines and reinforced concrete structures and so on. The interfacial metallurgical bonding between AZ63 sacrificial anode and Q235 wiring terminal directly affects its cathodic protection performance. Therefore, microstructure and mechanical properties of interfacial between AZ63 and Q235 by solid–liquid compound casting with hot-dip galvanized and post-casting solution-aging treatment (T6) were investigated. The results indicate that hot-dip galvanizing on the surface of Q235 is beneficial to the formation of intermetallic compounds at the interface. At the same time, it can promote the metallurgical bonding of the interface between AZ63 and Q235. After T6 heat treatment, the intermetallic compound at the interface between AZ63 and galvanized Q235 was refined. The electron-probe microanalyzer (EPMA) revealed that the intermetallic compounds at the interfaces between AZ63 and galvanized Q235 were Fe2Al5 before and after T6 treatment. Push-out testing and microhardness were used to investigate the mechanical properties of interface between AZ63 and Q235. It is shown that the hot-dip galvanization of the Q235 surface and T6 treatment were beneficial to improve the metallurgical bonding shear strength and microhardness of the interface. After T6 heat treatment, the highest shear strength at the interface between AZ63 and galvanized Q235 was up to 31.9 ± 1.9 MPa.

Improving Shear Strength of Ti/Mg Bimetal Composites Prepared by Hot‐Dip Aluminizing and Solid–Liquid Compound Casting

It is a great challenge to achieve the joining between Ti and Mg for their low solid solubility and positive formation enthalpy value. To fabricate high strength TC4/AZ91D bimetallic composite with metallurgical bonding interface, Al coating is prepared on the surface of TC4 alloy by hot‐dip technology, and Al‐coated TC4/AZ91D bimetal is prepared by solid–liquid compound casting herein. The effect of the hot‐dip process on the thickness and composition of the Al coating on the TC4 sample is discussed. Process parameters including casting temperature and liquid‐to‐solid volume ratio are investigated. The results reveal that the shear strength of Al‐coated TC4/AZ91D bimetal reaches 48.5 MPa when hot dipping at 700 °C for 15 min and casting at 720 °C with the volume ratio of 24, while that of the sample without Al interlayer is only 19.1 MPa. The reason is due to the formation of Ti(Al, Mg)3 intermetallic compound and Al12Mg17 + δ‐Mg eutectic structure at the interface. The results are helpful for the further development of high strength Ti/Mg bimetal by combining hot‐dip technology and solid–liquid composite casting technology.

Microstructures and mechanical properties of TC4/AZ91D bimetal prepared by solid–liquid compound casting combined with Zn/Al composite interlayer

To achieve Ti/Mg bimetallic composite with high strength and metallurgical bonding interface, Al interlayer and Zn/Al composite interlayer were used to prepare TC4/AZ91D bimetal composite with metallurgical bonding interface by solid–liquid compound casting, respectively. Al interlayer was prepared on the surface of TC4 alloy by hot dipping, and Zn/Al composite interlayer was prepared by electroplating process. The results suggested that the phases across the interface were AlTi and α(Al) + Mg21(Al, Zn)17 when Zn/Al composite interlayer was used. When Al interlayer was used as interlayer, AlMgTi ternary structure and Al12Mg17 + δ-Mg eutectic structure were the main phases at the interface. The shear strength of TC4/AZ91D bimetal with Zn/Al composite interlayer was much higher than that with pure Al interlayer, and the value of the shear strength was increased from 48.5 to 67.4 MPa. Thermodynamic models based on different compositions of the interface were established to explain the microstructure evolution of the interfacial zone.

Structures and macrosegregation of a 2024 aluminum alloy fabricated by direct chill casting with double cooling field

Central region coarse grains and centerline segregation are common defects in aluminum ingots fabricated by direct chill (DC) casting. A double cooling field was introduced into the DC casting process to reduce these defects, whereby the external cooling was supplied by the mold and water jets, and intercooling was achieved by inserting a rod of the same alloy into the molten pool along the central axis of the ingot. Rather than forming a good metallurgical interface during solid-liquid compound casting, in the present work, the purpose of inserting the rod is to enforce internal cooling and consequently decrease the sump depth. Moreover, the insertion provides more nucleation sites with the unmolten á-Al particles. The structure and the macrosegregation of 2024 Al alloy ingots prepared by DC casting with and without the inserts were investigated. Results show that when the inserting position is 50 mm above the upper edge of the graphite ring, significant grain refinement in the central region of the ingot and a reduced centerline segregation are achieved.

Effect of electro-spark deposited ZA12 interlayer on the microstructure and mechanical property of A356/AZ91D by liquid-solid compound casting

In this paper, to fabricate high strength Al/Mg bimetallic composite without the formation of Al12Mg17 intermetallic compound at the interface, ZA12 deposited A356/AZ91D bimetal was achieved by liquid-solid compound casting. The combination between electro-spark technology and compound casting was realized. The process parameters of electro-spark deposition were optimized by considering the thickness, quality, and efficiency of the coating. The microstructure, phase composition and mechanical properties of A356/AZ91D bimetal without and with ZA12 coating were investigated. From AZ91D to A356, the main phases formed across the interface region are: Mg17(Al, Zn)12 + α-Mg in diffusion layer I, Al5Mg11Zn4 and Mg32(Al, Zn)49 in diffusion layer II, and Al3Mg2 and Mg2Si in diffusion layer III. The microhardness of the interface is obviously higher than that of the substrate on both sides. The average shear strength of ZA12 coated A356/AZ91D bimetal is 69.2 MPa. The interface microstructure evolution mechanism of ZA12 coated A356/AZ91D by liquid-solid compound casting was analyzed. The result is helpful for further development of high strength Al/Mg bimetallic composites.

Influence of Retrogression and Reaging Treatment on Microstructure and Microhardness of the 3A21/7075 Aluminum Alloy Cladding Material

The 7075 aluminum alloy was an important structural material in the field of aeronautics and astronautics. With the development of this field, the requirements for its comprehensive properties were increasing. A novel casting method, the impact jet solid-liquid compound casting, was adopted to fabricate the 3A21/7075 aluminum alloy cladding material. Retrogression and reaging (RRA) treatment was further applied to the 3A21/7075 aluminum alloy cladding material in order to investigate the influence of RRA on microstructure and microhardness of the 3A21/7075 aluminum alloy cladding material. Then, the electron backscattered diffraction (EBSD) technique and the transmission electron microscope (TEM) together with the energy dispersive spectrometer (EDS) and the hardness test were utilized to analyze the influence of RRA treatment on microstructure and hardness of the 3A21/7075 aluminum alloy cladding material. The research results showed the 3A21/7075 aluminum alloy cladding material had better deformability. The amount of fine and dispersed phases precipitated in grains was in favor of improving the comprehensive mechanical properties of the 3A21/7075 aluminum alloy cladding material. This research might provide data and a theoretical approach for the engineering application of the 3A21/7075 aluminum alloy cladding material.

An Empirical Model for Carbon Diffusion in Grey Iron/Stainless Steel Bimetallic Composites Incorporating Eutectic Carbides

The mechanism of carbon diffusion in the as-cast and heat-treated grey iron and 304 stainless steel bimetallic composites was investigated in this study. A simplistic empirical model for the interface carbon diffusion was proposed and has been validated against the experimental data. A liquid-solid compound casting technique was used to fabricate the bimetallic composites. For the graphitizing annealing heat treatment, the bimetallic composite specimens were heated to 940 °C and held for 120 min and 240 min in an electric heating furnace. The proposed empirical model is based on the presence of eutectic carbides chill zone near the interface that formed during solidification of the liquid grey iron above the solid stainless steel substrate. It was found that the calculated carbon concentration profiles based on the proposed diffusion model were in good agreement with the experimental results.

Influence of Ni interlayer on interfacial microstructure and mechanical properties of Ti-6Al-4V/AZ91D bimetals fabricated by a solid–liquid compound casting process

Abstract The solid–liquid compound casting of Mg-AZ91D and Ti-TC4 alloys was developed by using pure Ni electro-deposited coating. The pouring temperatures of 660 ℃, 690 ℃, 720 ℃ and 750 ℃ were chosen to investigated the effects of casting temperatures on microstructural evolution, properties, and fracture behaviors of Ni-coated TC4/AZ91D bimetals by the solid–liquid compound casting (SLCC). The scanning electron microscopy (SEM) and the energy dispersive spectroscopy (EDS) results showed that the interfacial zone mainly composed of nickel, Mg2Ni and Mg-Al-Ni in the bimetals cast at 660 ℃. As the pouring temperature was increased to 750 ℃, the width of the interface zone, which mainly composed of δ(Mg), Mg2Ni, Mg-Al-Ni, Mg3TiNi2 and Al3Ni, gradually increased. The microhardness tests showed that the micro-hardness of the interface zone was smaller than that of TC4 substrate but larger than that of the cast AZ91D matrix. At the pouring temperature of 720 ℃, the Ni-coated TC4/AZ91D bimetals had the most typical homogeneous interface, which had granular Mg-Al-Ni ternary phase but no ribbon-like Al3Ni binary phase, and achieved the highest shear strength of 97.35 Mpa. Meanwhile, further fracture behavior analysis showed that most fracture failure of Ni-coated TC4/AZ91D bimetals occurred at the Mg2Ni + δ(Mg) eutectic structure and Al3Ni hard intermetallic.

Fabrication and microstructural analysis of 3A21/7075 aluminum alloy cladding material based on impact jet solid–liquid compound casting

To solve thickness problem for high-strength aluminum alloy used as plastic mold materials and eliminate oxide film on the surface of aluminum alloy, a new compound casting, namely impact jet solid–liquid compound casting, was developed to fabricate 3A21/7075 aluminum alloy cladding material. Then, optical microscope (OM), electron-backscattered diffraction (EBSD) technique, and transmission electron microscope (TEM) together with energy-dispersive spectrometer (EDS) were used to analyze microstructure of 3A21/7075 aluminum alloy cladding material. The OM and EBSD results showed that the 3A21/7075 aluminum alloy cladding material was composed of 3A21 cladding layer, fusion zone (FZ), heat-affected zone, and 7075 matrix. The grain morphology on both sides of FZ had great differences. Moreover, the TEM and EDS results showed that the 3A21 cladding layer showed a bulk phase and lots of fine and dispersed granular phases, while the 7075 matrix appeared undetermined strip phases and amounts of fine and dispersed rod-like phases. Moreover, FZ existed a great deal of fine and dispersed granular phases and rod-like phases. The 3A21/7075 aluminum alloy cladding material could effectively solve the problems mentioned above and the in-depth analysis of microstructures of 3A21/7075 aluminum alloy cladding material was of great importance in terms of engineering value and academic significance.

Novel and simple technique for interfacial shear strength of liquid-solid compound casting specimen

A novel testing technique for the interfacial shear strength of the liquid-solid compound casting specimen was designed. Two different bimetallic materials specimens were fabricated and subsequent cut for interfacial shear testing. To ensure the easy cutting and testing of bimetallic specimen, two kinds of bearing materials were cast into metallic mold contain two different ferrous solid substrates. Direct tinning process using a mixture of tin powder and flux was applied on the solid substrates before pouring the liquid metal. In current novel testing technique, a minimum cutting and machining processing on the bimetal casting specimen were applied to minimize the internal stresses resulted from multi steps of cutting and machining processes that used in other interfacial shear strength testing techniques. Other previously used shear strength testing technique for bimetal materials was used for a comparison with the current technique. The present shear test technique offers simple and convenient approach for preparing and testing the bimetallic specimens.

Improved interface bonding of Mg/aluminized steel bimetallic castings prepared by solid–liquid compound casting process

ABSTRACT The effect of pouring temperature on microstructure and bonding properties of the Mg/aluminised steel bimetallic castings prepared by the solid–liquid compound casting process was investigated in this paper in order to improve the interface bonding of the Mg/aluminised steel bimetallic castings. The results show that the Mg/aluminised steel bimetallic castings produced with different pouring temperatures obtained a uniform interface layer that was mainly composed of the Fe2Al5, τ10-Al9Fe4Si3, FeAl3 and Al12Mg17 phases. When the pouring temperature was low, the cracks were formed between the Mg and the interface layer. With increasing pouring temperature, a compact interface bonding was achieved. The bonding properties of the Mg/aluminised steel bimetallic castings increased with increasing pouring temperature. An optimised bonding of the Mg/aluminised steel bimetallic castings was obtained with a pouring temperature of 780°C.

Development and Optimization of Tin/Flux Mixture for Direct Tinning and Interfacial Bonding in Aluminum/Steel Bimetallic Compound Casting.

Interfacial bonding highly affects the quality of bimetallic bearing materials, which primarily depend upon the surface quality of a solid metal substrate in liquid–solid compound casting. In many cases, an intermediate thin metallic layer is deposited on the solid substrate before depositing the liquid metal, which improves the interfacial bonding of the opposing materials. The present work aims to develop and optimize the tinning process of a solid carbon steel substrate after incorporating flux constituents with the tin powder. Five ratios of tin-to-flux—i.e., 1:1, 1:5, 1:10, 1:15, and 1:20—were used for tinning process of carbon steel solid substrate. Furthermore, the effect of volume ratios of liquid Al-based bearing alloy to solid steel substrate were also varied—i.e., 5:1, 6.5:1 and 8.5:1—to optimize the microstructural and mechanical performance, which were evaluated by interfacial microstructural investigation, bonding area determination, hardness and interfacial strength measurements. It was found that a tin-to-flux ratio of 1:10 offered the optimum performance in AlSn12Si4Cu1/steel bimetallic materials, showing a homogenous and continuous interfacial layer structure, while tinned steels using other percentages showed discontinuous and thin layers, as in 1:5 and 1:15, respectively. Furthermore, bimetallic interfacial bonding area and hardness increased by increasing the volume ratio of liquid Al alloy to solid steel substrate. A complete interface bonding area was achieved by using the volume ratio of liquid Al alloy to solid steel substrate of ≥8.5.

Characterization of the Bonding Zone in AZ91/AlSi12 Bimetals Fabricated by Liquid-Solid Compound Casting Using Unmodified and Thermally Modified AlSi12 Alloy

Liquid-solid compound casting was used to produce two types of AZ91/AlSi12 joints. The magnesium alloy was the cast material poured onto a solid aluminium alloy insert with an unmodified or modified structure. The bonding zone obtained for the unmodified insert was not uniform in thickness. There was a eutectic region (Mg17Al12 + a solid solution of Al in Mg) in the area closest to the AZ91. The region adjacent to the AlSi12 had a non-uniform structure with partly reacted Si particles surrounded by the Mg2Si phase and agglomerates of Mg2Si particles unevenly distributed in the Mg-Al intermetallic phases matrix. Cracks were detected in this region. In the AZ91/AlSi12 joint produced with a thermally modified AlSi12 insert, the bonding zone was uniform in thickness. The region closest to the AZ91 alloy also had a eutectic structure. However, significant microstructural changes were reported in the region adjacent to the modified AlSi12 alloy. The microstructure of the region was uniform with no cracks; the fine Mg2Si particles were evenly distributed over the Mg-Al intermetallic phase matrix. The study revealed that in both cases the microhardness of the bonding zone was several times higher than those of the individual alloys; however, during indenter loading, the bonding zone fabricated from modified AlSi12 alloy was less prone to cracking.

Effect of pouring temperature during a novel solid–liquid compound casting process on microstructure and mechanical properties of AZ91D magnesium alloy parts with arc-sprayed aluminum coatings

Aluminum (Al)/AZ91D magnesium (Mg) alloy bimetals, i.e., AZ91D magnesium alloy parts with Al coatings, were produced by pouring liquid Mg alloy, at temperatures of 933, 963, 993 and 1023 K, into molds with an arc-sprayed Al coating deposited. It was shown that an interface zone was generated in the Al/AZ91D bimetal produced by this novel solid–liquid compound casting technique, when the pouring temperature wasn't lower than 963 K. A mixing zone, composed of Al, alumina and MgAl2O4, was formed in the bimetal cast at 933 K. When the pouring temperature was increased from 963 to 1023 K, the interface zone mainly comprising the Al–Mg intermetallic compounds increased in thickness, and the γ-Al12Mg17 intermetallic compounds in this zone tended to grow toward the Mg alloy side. The obtained interface zones of the Al/AZ91D bimetals showed greater microhardness than the substrate and the coating metal. At a pouring temperature of 993 K, the Al/AZ91D bimetal had the thinnest interface zone without any untransformed Al pieces and thread-like MgAl2O4, leading to the highest shear strength of 25 MPa. Since the expansion of the interface zone increased the possibility of brittle fracture, an excessive increase in the pouring temperature did not necessarily improve the adhesive strength between the as-cast AZ91D and the arc-sprayed Al coating.

Effect of the Vacuum Heat Treatment on the Microstructure and Mechanical Properties of the Galvanized-Q235/AZ91D Bimetal Material Produced by Solid–Liquid Compound Casting

The galvanized-Q235/AZ91D bimetallic material was achieved via solid–liquid compound casting, and the effect of the heat treatment at 250 °C for 3 h on the microstructure and mechanical properties of the galvanized-Q235/AZ91D bimetallic material were investigated. The interface zone in the galvanized-Q235/AZ91D was composed of three different layers which were the FeAl3 + α-Mg, (α-Mg + MgZn), and α-Mg + (α-Mg + MgZn) from the galvanized-Q235 to AZ91D, successively. After the heat treatment, the (α-Mg + MgZn) eutectic structure was transformed into Al5Mg11Zn4 to promote the microhardness from 139.2 HV to reach 298.8 HV. In addition, the α-Mg and (α-Mg + Mg12Al17) eutectic structure in AZ91D were separately transformed into (α-Mg + Al5Mg11Zn4) and Al5Mg11Zn4 resulting in the increasement of microhardness, from 59.5 to 173.4 HV and 294.2 HV, respectively. Moreover, the interfacial shear strength was changed from 11.23 to 24.63 MPa due to the formation of Al5Mg11Zn4 and the vanishment of MgZn.

Influence of a Zn Interlayer on the Interfacial Microstructures and Mechanical Properties of Arc-Sprayed Al/AZ91D Bimetals Manufactured by the Solid-Liquid Compound Casting Process.

A novel technique combining solid–liquid compound casting (SLCC) with arc spraying was designed to manufacture the arc-sprayed Al/AZ91D bimetals with a Zn interlayer. The Al/Mg bimetal was produced by pouring the AZ91D melt into the molds sprayed with Al/Zn double-deck coating, during which the arc-sprayed Zn coating acted as the interlayer. The effect of the Zn interlayer on microstructures, properties, and fracture behaviors of arc-sprayed Al/AZ91D bimetals by SLCC was investigated and discussed in this study. The optimal process parameter was acquired by analyzing the results from different combinations between the arc-spraying time of the Zn coating (10, 18, and 30 s) and the preheat time of the Al/Zn double-deck coating (6 and 12 h). The interfacial microstructures of the arc-sprayed Al/AZ91D bimetals with a Zn interlayer could be approximately divided into two categories: One was mainly composed of (α-Mg + Al5Mg11Zn4) and (α-Al + Mg32(Al, Zn)49) structures, and the other primarily consisted of (α-Mg + Al5Mg11Zn4), (MgZn2 (main) + β-Zn), and (β-Zn (main) + MgZn2) structures. In the interface zone, the (α-Mg + Al5Mg11Zn4) structure was the most abundant structure, and the MgZn2 intermetallic compound had the highest microhardness of 327 HV. When the arc-spraying time of the Zn coating was 30 s and the preheat time of the Al/Zn double-deck coating was 6 h, the shear strength of the arc-sprayed Al/AZ91D bimetal reached 31.73 MPa. Most rupture of the arc-sprayed Al/AZ91D bimetals with a Zn interlayer occurred at the (α-Mg + Al5Mg11Zn4) structure and presented some typical features of brittle fracture.