Aluminum Clad Research Articles

アルミニウム/銅クラッド材接合界面における金属間化合物の形成

It is difficult to bond dissimilar metals such as aluminium and copper using diffusion bonding of dissimilar materials because intermetallic compounds are easily produced at the bond interface and they cause the decline of bonding strength. However, as the aluminium clad copper were produced by vacuum roll bonding, hundreds nm of intermetallic phases are formed on the bond interface. On the tensile testing, it is broken from the base metal of aluminium and high bond tensile strength is available. In this study, heat-treatment has been taken to aluminium-clad copper produced by vacuum roll bonding. Observation of microstructure, EPMA, and XRD have been carried to the investigation of the formation of inter-metallic phases. As a result, it is clarified that 3 types of intermetallic phases such as CuAl2, CuAl and Cu9Al4 are formed at the bond interface of Al/Cu clad materials after heat-treatment. And the apparent activation energy of the intermetallic phases for growth behavior has been calculated. It was clarified that the apparent activation energy of CuAl and Cu9Al4 is lower than CuAl2. The affect of intermetallic phases on bond strength has also been carried to investigate with the growth of intermetallic phases. The decrease of tensile strength has been clarified. The broken position is in the CuAl2 or between CuAl2 and CuAl. Furthermore, the bond strength of Al/Cu clad material is seriously affected by the thickness of CuAl2.

Effects of Processing Parameters on the Fabrication of Copper Cladding Aluminum Rods by Horizontal Core-Filling Continuous Casting

Copper cladding aluminum (CCA) rods with a diameter of 30 mm and a sheath thickness of 3 mm were fabricated by horizontal core-filling continuous casting (HCFC) technology. The effects of key processing parameters, such as the length of the mandrel tube of composite mold, aluminum casting temperature, flux of the secondary cooling water, and mean withdrawing speed were optimized based on some quality criteria, including the uniformity of the sheath thickness, integrality of the rods, and thickness of the interface. The causes of internal flaws formation of CCA rods were also discussed. The results showed that the continuity of the liquid aluminum core-filling process and the interface reaction control between solid copper and liquid aluminum were two key problems that strongly affected the stability of the casting process and the product quality. Our research indicated that for the CCA rod with the previously mentioned size, the optimal length of mandrel tube was 210 mm. A shorter mandrel tube allowed of easier erosion at the interface, which led to a nonuniform sheath thickness. Conversely, it tended to result in a discontinuous filling process of liquid aluminum, which causes shrinkage or cold shuts. The optimal casting temperatures of copper and aluminum were 1503 K (1230 °C) and 1043 K to 1123 K (770 °C to 850 °C), respectively. When the casting temperature of aluminum was below 1043 K (770 °C), the casting process would be discontinuous, resulting in shrinkages or cold shuts. Nevertheless, when the casting temperature of aluminum was higher than 1123 K (850 °C), a severe interface reaction between solid copper and liquid aluminum would occur. The proper flux of the secondary cooling water and the mean withdrawing speed were determined as 600 to 800 L/h and 60 to 87 mm/min, respectively. In the previously mentioned proper ranges of processing parameters, the interfacial shear strengths of CCA rods were 40.5 to 67.9 MPa.

Fabrication of Monolithic RERTR Fuels by Hot Isostatic Pressing

The Reduced Enrichment for Research and Test Reactors (RERTR) program develops advanced nuclear fuels for high-power test reactors. Monolithic fuel design provides higher uranium loading than that of the traditional dispersion fuel design. Hot isostatic pressing is a promising process for low-cost batch fabrication of monolithic RERTR fuel plates for these high-power reactors. Bonding U-Mo fuel foil and 6061-Al cladding by hot isostatic press bonding was successfully developed at Idaho National Laboratory. Because of the relatively high processing temperature, the interaction between fuel meat and aluminum cladding is a concern. Two different methods were employed to mitigate this effect: a diffusion barrier and a doping addition to the interface. Both types of fuel plates have been fabricated by hot isostatic press bonding. Preliminary results show that the direct fuel/cladding interaction during the bonding process was eliminated by introducing a thin zirconium diffusion barrier layer between the fuel and the cladding. Fuel plates were also produced and characterized with a silicon-rich interlayer between fuel and cladding. This paper reports the recent progress of this developmental effort and identifies the areas that need further attention.

Self‐brazing aluminium clad steel

AbstractAluminium clad steel strip FERAN®, produced by cold roll bonding, combines the forming and mechanical properties of low carbon, unalloyed deep drawing steel with the surface properties of Aluminium. Self‐brazing Aluminium clad steel is a material with the additional property that it can be brazed just like Aluminium brazing strip. The steel core provides for increased strength, especially at higher temperatures, and erosion resistance. Samples of self‐brazing Aluminium clad steel strip have been manufactured on a cladding pilot plant. Brazing tests with a NOCOLOK® fluxing agent at various temperatures and times were performed. The formed joints were investigated metallographically and by SEM/EDX.Mittels Kaltwalzplattieren hergestelltes aluminiumplattiertes Stahlband FERAN® kombiniert die gute Umformbarkeit und die mechanischen Eigenschaften eines niedrig gekohlten unlegierten Stahls mit den Oberflächeneigenschaften von Aluminium. Selbstlötender aluminiumplattierter Stahl kann zudem analog zu lotplattiertem Aluminiumband hartgelötet werden. Der Stahlkern bringt dabei insbesondere verbesserte Erosionsbeständigkeit und Festigkeit bei erhöhten Temperaturen in den Verbund ein. Proben aus lotfähigem aluminiumplattierten Stahl wurden auf einem Technikums‐Plattiergerüst hergestellt und bei verschiedenen Temperaturen und Zeiten mit einem NOCOLOK® Flussmittel verlötet. Die Lötverbindungen wurden lichtmikroskopisch und mit REM/EDX untersucht.

Forming Limit Diagram of Stainless Steel-Aluminum Alloy Clad

The forming limit diagram of clad was developed with Hill’s instability criterion and M–K analysis at the positive strain ratio. The relationships of forming limit with stain path, thickness ratio and thickness irregular coefficient were analyzed. The results show that the forming limit of clad material is between those of its component materials, and increase with the rising of stainless steel thickness ratio and the thickness irregular coefficient. The most suitable value of f0 is 0.094 and the stainless steel aluminum clad break with local interfacial cracks.

Study on Surface Quality of Lead Clad Tin Bimetal Continuous Casting by Air Pressing Core-Filling

To provide theoretical basis and practical guidance of preparing copper clad aluminum composite rods by directly continuous casting, low melting point materials of lead and tin were selected to prepare composite rods of external diameter Φ12mm and inner diameter Φ8mm through adopting air pressing core filled continuous casting processing. The orthogonal tests consisting of three factors of melting lead temperature, continuous casting speed and inflation pressure at three different levels were designed to obtain arrangements of optimal process parameters that affected surface quality of bimetal casting rods in principle. The experiments showed that composite rods have excellent surface quality under the condition of melting lead temperature,375 , continuous casting speed, 10 mm/min, and inflation pressure, 0.03MPa.

The Deformation of Clad Aluminum Sheet Produced By Direct Chill Casting

The tensile and bending response of AA3003/AA6111 sheet produced by direct chill casting has been investigated. It is shown that the interface strength of the clad sheet has a minimum value of 175 MPa, and failure does not occur in the interface. The yield strength of the clad sheet obeys the rule of mixtures, and up to a cladding thickness of 100 μm—which was the thickest investigated—the work hardening behavior and tensile response are essentially unaffected by the presence of the cladding. The bending response of the sheet is improved greatly by the presence of ductile cladding, which was the case for prestrained and aged sheet. Under bending, failure is initiated in the lower bendability core and then eventually propagates through the more ductile cladding, which yields the final bend failure.

An effective warm forming process; numerical and experimental study

To investigate the effectiveness of the warm forming a coupled thermo-mechanical model is developed in LS-Dyna. The temperature dependant material properties of the material, a long-life 3000 series clad aluminum alloy brazing sheet are modelled using a user defined material subroutine accommodating the Barlat YLD2000 anisotropic plane-stress yield surface and the physically motivated Bergstrom hardening rule. The maximum thickness reduction is adopted as a simplified failure criteria to determine both the location and failure depth for the numerical models. The original progressive tooling is modified to incorporate the application of individual temperatures on the dies and the punch. The dies (die and blank holder) are heated with embedded cartridge heaters and the punch is cooled by circulation of chilled water. Select experimental cases are modelled. FEA model is validated against experimental results by comparing punch force versus displacement as well as failure location. The numerical results for either successful or failed simulations are compared with corresponding experimental samples.

Hydrodynamic transition delay in rectangular channels under high heat flux

When upgrading a research nuclear reactor for a higher power output it can be expected that the cooling flow rate has to be increased. In the case of a reactor designed with a laminar cooling flow this upgrade may take the flow into the transition hydrodynamic regime. In this work we explore experimentally the laminar to turbulent transition in a rectangular channel with similar characteristics as the refrigerating passages between the fuel plates in a research reactor core. The measurements were performed under heat fluxes up to 10 W/cm 2, which is similar to the heat flux found in pool type research reactors. Special care has been taken in the test section to minimize the entrance turbulence and to reproduce the superficial characteristics of the aluminium cladding of the nuclear fuel. We have measured the transition Reynolds number as the bulk Reynolds number at the point of minimum Nusselt number for each condition studied. It was observed that the bulk Reynolds number at which the transition to turbulence is detected depends on the heat flux at the walls. This result is in agreement with a recent theoretical analysis, which shows that property variations near the wall, particularly the reduction of viscosity, have a stabilizing effect on the flow.

Microstructure of Bonding Interface in Explosively Welded Metal/Ceramic Clad

Bonding interface in aluminum (Al) and silicon nitride (Si3N4) clad fabricated by explosive welding has been investigated by transmission electron microscopy (TEM). The nanocrystalline region was clearly observed at the interface between Al and Si3N4. Electron diffraction pattern and energy dispersive X-ray spectroscopy (EDS) measurements across the interface revealed that this nanocrystalline region consist of the only aluminum.

基于统计模型优化的铝合金激光熔覆研究

基于统计模型优化的铝合金激光熔覆研究

Bauschinger Effect on Springback of Clad Sheet Metals in Draw Bending

For clad sheet metals, springback behavior is directly related to the elastic-plastic properties such as Young’s modulus, the yield strength, workhardening and the Bauschinger effect of each metal layer. The aim of this study is to understand the springback characteristics of the clad sheet metals in draw bending based on the accurate FE simulation corresponding to experimental data on stainless-steel clad aluminum sheets. In the discussion, the special emphasis is placed on the influence of the Bauschinger effect. For that purpose, in the simulation, two types of material models, one is the classical isotropic hardening model (no Bauschinger effect included) and the other Yoshida-Uemori kinematic hardening model which describes the Bauschinger effect of materials properly, were used and these numerical results were compared.

Air bending and springback of stainless steel clad aluminum sheet

This paper deals with bending and springback phenomena of a stainless-steel clad aluminum sheet in V-shaped air bending. The aim of this study is to investigate the bending characteristics such as sheet thickness change and the bending angles of the sheet before/after springback. The first part of this paper is on the experimental observations. V-bending experiments were performed for both the cases of Al in/SS out (i.e., aluminum layer is located inside the bent clad) and SS in/Al out (i.e., stainless-steel layer is located inside the bent clad). From these results, it was found that the sheet-set condition (either Al in/SS out or SS in/Al out) has a great influence on the bending phenomena. In the second part, the accurate prediction of springback by FE analysis, especially the role of elasto-plasticity models, is discussed. When using Yoshida–Uemori kinematic hardening model (F. Yoshida, T. Uemori, Int. J. Plasticity 18, 2002; Int. J. Mech. Sci., 45, 2003), which well describes the Bauschinger effect of materials, the springback of the clad sheet is accurately calculated, whereas the classical isotropic hardening model underestimates the springback.

Prospects of using different clad materials in a material test research reactor – part 4 – the uncontrolled reactivity insertion transients

The effects of using different clad materials on the uncontrolled reactivity insertion transients of a material test research reactor were studied. For this purpose, the aluminium clad of an MTR was replaced separately with stainless steel-316 and zircaloy–4. Simulations were carried out to determine the reactor performance under reactivity insertion transients with totally failed control rods. Ramp reactivities of 0.25$/0.5 s and 1.35$/0.5 s were inserted with reactor operating at full power level of 10 MW. Nuclear reactor analysis code PARET was employed to carry out these calculations. It was observed that when reactivity insertion was 0.25$/0.5 s, all the reactors stabilised at new power levels. The SS cladded fuel attained the minimum power level of 17.72 MW, followed by Zr-4 cladded with 23.62 MW while it was maximum at 24.31 MW for Al cladded fuel. When reactivity insertion was 1.35$/0.5 s, the feedback reactivities were unable to control the reactor which resulted in the bulk boiling of the coolant; the Al cladded was the first to reach ONB while SS cladded was the last.

Effect of tool profile and fatigue loading on the local hardness around scratches in clad and unclad aluminium alloy 2024

Nanoindentation has been used to study the hardness changes produced by scratching of aluminium alloy AA2024, with and without a clad layer of pure aluminium. The hardness was mapped around scratches made with diamond tools of different profiles. One tool produced significant plastic damage with associated hardening at the scratch root, whilst the other produced a ‘cleaner’ cut with no hardening. The different behaviours are attributed to whether the tool makes the scratch by a ‘cutting’ or a ‘ploughing’ mechanism. The degree of plastic damage around the scratches has been correlated with peak broadening data obtained using synchrotron X-ray diffraction. There was no change observed in the local hardness around the scratch with fatigue loading.

Prospects of using different clad materials in a material test research reactor – Part 3 – The dynamic behavior

The effects of using different clad materials on the dynamics of a material test research reactor were studied. For this purpose, the aluminum clad of an MTR was replaced separately with stainless steel-316 and zircaloy-4. Simulations were carried out to determine the reactor performance under reactivity insertion and loss-of-flow transients. Nuclear reactor analysis code PARET was employed to carry out these calculations. It was observed that during the fast reactivity insertion transient, Al cladded fuel attained the maximum reactor power of 59.34 MW, while stainless steel-316 cladded attained 48.74 MW and zircaloy-4 cladded attained maximum power of 55.87 MW. During the slow reactivity insertion transient, Al cladded fuel attained the maximum reactor power of 12.38 MW, while stainless steel-316 cladded attained 12.23 MW and zircaloy-4 cladded attained maximum power of 12.34 MW. During the loss-of-flow transients, the reactor power of the stainless steel-316 cladded fuel remained slightly lower than the other two. The fuel temperature of stainless steel-316 and zircaloy-4 cladded fuels remained higher due to poor fuel–clad gap conductance.

Assessment of durability clad aluminum alloys in asymmetric cyclic loading

Comparative efficiency analysis of the two methods of the residual fatigue life estimation under asymmetric cyclical loading has been conducted. It is shown, that the method, based on the determination of the developed on the surface of aluminium alloy D-16AT deformation relief parameters has every reason to compete with known approach, that takes into account indices of asymmetry and uses the diagram of the material’s ultimate state.

Prospects of using different clad materials in a material test research reactor – Part 2 – The reactivity feedback coefficients

The reactivity feedback coefficients of a material test research reactor using stainless steel-316 and zircaloy-4 as clad were calculated. For this purpose, the aluminum clad of an MTR was replaced with stainless steel-316 and zircaloy-4. Calculations were carried out to find the fuel temperature reactivity feedback coefficient, clad temperature reactivity feedback coefficient, moderator temperature reactivity feedback coefficient and moderator density reactivity feedback coefficient. Nuclear reactor analysis codes including WIMS-D4 and CITATION were employed to carry out these calculations. It is observed that the average values of fuel temperature reactivity feedback coefficient, moderator temperature reactivity coefficient and moderator density reactivity coefficient from 38 °C to 50 °C, at the beginning of life, were maximum in magnitude for stainless steel-316 cladded fuel, followed by aluminum and least for the zircaloy-4 cladded fuel. The fuel temperature feedback coefficient increased in magnitude by 47.37% for stainless steel-316 and decreased by 4.72% for zircaloy-4 clad. The moderator temperature feedback coefficient increased in magnitude by 60.41% for stainless steel-316 and decreased by 3.03% for zircaloy-4 clad, while the moderator density feedback coefficient showed an increase in magnitude of 59.18% for stainless steel-316 and a decrease of 7.63% for zircaloy-4 clad. Zircaloy-4 gave a positive value for clad temperature feedback coefficient, while the others two did not have any clad temperature feedback coefficient.

Novel Metal Monolithic Anodic Alumina Catalyst for Methane Catalytic Combustion, the External Heat Source for Methane Steam Reforming

A novel metal monolithic anodic γ-Al2O3 support was prepared by anodization using a clad aluminum plate. The catalytic combustion of methane on Pt/Al2O3/Alloy, Pd/Al2O3/Alloy and Pd–Pt/Al2O3/Alloy catalysts prepared by the impregnation method was studied. The catalysts were characterized by ICP, BET, and temperature-programmed oxidation (TPO). The results showed that at low temperatures ( 700°C), Pd–Pt/Al2O3/Alloy showed the best activity among these three catalysts, whereas the activity of Pd/Al2O3/Alloy decreased gradually. Therefore, it was concluded that the co-existence of Pd and Pt in the Al2O3/Alloy support in Pd–Pt/Al2O3/Alloy made its activity the best among that of all the catalysts studied over the entire temperature range (400–800°C) considered for methane combustion.

Prospects of using different clad materials in a material test research reactor – Part 1 – The kinetic parameters

The kinetic parameters of a material test research reactor using stainless steel-316 and zircaloy-4 as clad were calculated. For this purpose, the aluminum clad of an MTR was replaced separately with stainless steel-316 and zircaloy-4. Calculations were carried out to find the core excess reactivity, neutron flux spectrum, prompt neutron generation time and effective delayed-neutron fraction. Nuclear reactor analysis codes including WIMS-D4 and CITATION were employed to carry out these calculations. It was observed that at the beginning of life, the excess reactivity was maximum at 0.054110 Δ k/ k when zircaloy-4 was used as clad while it was minimum at −0.365650 Δ k/ k when stainless steel-316 was the clad as compared to 0.017945 Δ k/ k for aluminum. The thermal neutron flux at the mid of the central flux trap increased by 59.9% and 12.5% for stainless steel and zircaloy-4 clads, respectively, from the flux of the original aluminum clad. The prompt neutron generation time was maximum at 45.36 μs when stainless steel-316 was the clad while it was minimum at 44.03 μs for the original aluminum clad. The effective delayed-neutron fraction was maximum at 0.007185 for the original aluminum clad while it was minimum at 0.007078 for stainless steel clad.