Bimetallic Tubes Research Articles

Performance of seawater sea sand concrete-filled bimetallic tube (SSCFBT) stub columns under axial partial compression

This study presents the experimental findings on the mechanical performance of circular seawater sea sand concrete (SSC)-filled bimetallic tube (SSCFBT) stub columns under axial partial compression. The proposed cross-sectional configuration of the bimetallic tube consists of an external layer fabricated with carbon steel and an inside layer fabricated with stainless steel, by doing so to prevent the chloride ions in SSC from corroding the external carbon steel tube-layer. Axial partial compression tests are conducted on twelve SSCFBT specimens with steel endplates and six counterparts without endplates, and the corresponding parameters include the partial compression area ratio, endplate thickness, and specimen dimensions. The test findings suggest that the two layers of the bimetallic tube exhibit effective composite actions and the SSCFBT stub columns show favorable load-carrying capacity and ductility. The effects of various parameters on the failure mechanism, load-deformation relationship, load-carrying capacity, and strain development of SSCFBT stub columns are analyzed. Finally, the suitability of using different available design codes for conventional concrete-filled steel tubes (CFST) to predict the axial partial compressive strength of SSCFBT stub columns is evaluated.

Co-Extrusion of Dissimilar Aluminum Alloys via Shear-Assisted Processing and Extrusion

Bimetallic tubes are used when a component requires more than one performance requirement, for instance, strength/creep resistance and oxidation/corrosion resistance. Shear-assisted processing and extrusion (ShAPE) can be used to fabricate extrudates that are comparable or superior in performance relative to conventionally manufactured extrudates. For the first time, ShAPE has been successfully employed in producing bimetallic Al tubing consisting of 6061 and 7075 Al alloys. Both light and electron microscopy techniques were used to investigate the integrity of the tubes, especially the interface between the core and cladding of the bimetallic tubes. Void-free bimetallic tubes were produced using ShAPE. Quantification of tube integrity was carried out with tensile testing under as-extruded and post-aged conditions. All the bimetallic tubes in the as-extruded samples exhibited uniform elongation above 5% with good tensile strength. Key insights such as material flow during bimetallic tube extrusion were obtained from the characterization of remnant billet and simulation results from a smoothed particle hydrodynamics model.

Processing of Bimetallic Inconel 625-16Mo3 Steel Tube via Supercritical Bend: Study of the Mechanical Properties and Structure.

Incineration is currently the standard way of disposing of municipal waste. It uses components protected by high-temperature-resistant layers of materials, such as Inconel alloys. Therefore, the objective of the current paper is to study the mechanical properties and structure of a bimetallic Inconel 625-16Mo3 steel tube. The Inconel 625 layer was 3.5 mm thick and was applied to the surface of the tube with a wall thickness of 7 mm via the cold metal transfer method. The bimetallic tube was bent using a supercritical bend (d ≤ 0.7D). This paper is focused on the investigation of the material changes in the Inconel 625 layer areas influenced by the maximum tensile and compressive stresses after the bend. The change in layer thickness after the bend was evaluated and compared to the non-deformed tube. In addition, the local mechanical properties (nanohardness, Young modulus) across the indicated interfacial areas using quasistatic nanoindentation were investigated. Subsequently, a thorough microstructure observation was carried out in areas with maximum tensile and compressive stresses to determine changes in the morphology and size of dendrites related to the effect of tensile or compressive stresses induced by bending. It was found that the grain featured a stretched secondary dendrite axis in the area of tensile stress, but compressive stress imparted a prolongation of the primary dendrite axis.

Solar power tower plants with Bimetallic receiver tubes: A thermomechanical study of two- and three-layer composite tubes configurations

The present study numerically investigated the use of bimetallic tubes for concentrating solar energy applications. Specifically, a billboard receiver employing supercritical carbon dioxide (sCO2) as the heat transfer fluid is considered, with tubes made of stainless steel 316 and GRCop-84. Two- and three-layer tube configurations are compared, exploring the impact of more thermally conductive layer thickness and placement on temperature and stress fields. The findings demonstrate that the use of bimetallic tubes can effectively reduce temperature and stress in the receiver tubes. In light of the results, it can be concluded that the higher thermal conductivity of GRCop-84 leads to a more uniform temperature distribution, resulting in lower temperature peaks on the outer tube surface, and reduced maximum stresses. Furthermore, it has been found that the incident heat flux necessary to achieve the same temperature increment of sCO2 inside the panel is 1.7% lower in a two-layer tube configuration where GRCop-84 is placed in the outer layer. Besides, the stress in the 316 layer can be reduced up to 53.2% with the cited configuration. Nevertheless, it is observed that it is more beneficial to tube performance to place the more conductive layer inside, since it reduces stress in the GRCop-84 layer, and its compressive stress and corrosion-resistant properties help to avoid the risk of stress-corrosion-cracking. In a three-layer composite tube configuration, placing the more thermally conductive GRCop-84 layer close to the outer tube wall decreases the maximum temperature while increasing stress. The opposite effect is achieved by placing the more conductive layer closer to the inner tube wall. Overall, the results demonstrate the potential benefits of using bimetallic tubes for solar energy applications, when the layers have similar thicknesses, since their use can enhance the thermomechanical performance of conventional tubes made with one layer of 316 stainless steel. This fact has important implications for the design of efficient and reliable solar thermal systems.

Numerical investigation and calculation method of concrete-filled bimetallic tubes subjected to concentric tension

Concrete-filled stainless steel (outer)-carbon steel (inner) bimetallic tubes (CFBT) are potential to be applied as structural members in the corrosion-prone environments. A detailed numerical investigation on the mechanical performance and calculation method of CFBT members under concentric tension is carried out in this paper. A finite element analysis (FEA) model adopting three-dimensional elements is established, and related experimental results of conventional concrete-filled carbon steel tubes (CFST) and concrete-filled stainless steel tubes (CFSST) are used to validate the FEA model. Then, the calibrated FEA model is used to investigate the performance of CFBT tensile members, especially the composite actions and stress distribution laws between the two tube-layers and the infilled concrete, which play the key role in the load-carrying capacity of the composite member. To quantitatively determine the influence of different parameters on the load-carrying capacity of CFBT tensile members, a wide-range parametric analysis is performed. Finally, a calculation model is proposed to be used to predict the ultimate tensile strength of CFBT members subjected to concentric tension, and the model-predicted values show good agreement with the FEA-computed results.

An investigation of bimetallic tube fabrication through a novel friction stir extrusion based technology for automotive applications

The bimetallic tubular component fabrication through a novel friction stir backward extrusion (FSBE) process has been proposed in this article. During the extrusion process, the bonding occurs between the substrate and cladding material due to diffusion. The frictional heat generated during the process leads to softening and extrusion of solid clad material that forms a layer on the substrate material. Different sets of materials have been used for feasibility testing. The results show that the process is capable of uniform cladding and void-free bonding for different sets of material. Energy dispersive spectroscopy (EDS) line scan and area mapping were performed at the interface to understand the diffusion pattern. At the interface, intermetallic compounds (IMCs) were confirmed via spot EDS and X-ray diffraction (XRD) analyses. Strong metallurgical bonding occurs between the substrate and the cladding material due to the interdiffusion of the materials, and the flattening test was performed to check the bonding efficacy. Thus, this process opens new opportunities for the fabrication of bimetallic tubular components, which can be used in electrical, structural, lightweight, and corrosion-resistance applications.

A novel dynamic self-constrained explosive welding method for manufacturing copper-steel bimetallic tube

This study proposed a dynamic self-constrained explosive welding method to fabricate the copper-steel bimetallic tube without external mold. The mechanical balance of the self-constrained process was carefully revealed by three-dimensional (3D) numerical simulations. Besides, the microstructure evolution, element distribution, and mechanical properties of the copper-steel interface were systematically investigated. Results showed that the dynamic self-constrained system could effectively strike a balance between the inner and outer tubes in terms of stress, velocity, and displacement. The max hoop tensile stress near the outer surface of the base tube was significantly reduced from 535 MPa (in the unconstrained experiment) to 387 MPa avoiding the appearance of radial cracks. The welding interface varied from a nearly straight one via a large wave to an irregularly small wave. Meanwhile, the microhardness test showed a significant increase in the region near the welding interface.

Study of Copper/Aluminum Bimetallic Tube Rotary Ring Spinning Composite Forming Characteristics

As a plastic forming process developed based on rotary wheel spinning technology, the rotary ring spinning process has the excellent characteristics of high forming accuracy and high material utilization rate, and has been gradually applied to the manufacture of bimetallic composite pipes. In this paper, the forming law of a bimetallic tube in the process of rotary ring spinning was analyzed by numerical simulation and experimentation. The results show that the deformation coordination of the basic and cover tubes increased with the increasing press amount, and the feed ratio had less of an effect on the thickness variation. In addition, the three-way strain of the basic and cover tubes and the degree of influence of the process parameters on the equivalent strain of the tubes were also studied. The results show that the radial strain on both tubes was the largest, followed by the axial strain, and the tangential strain was the smallest; the press amount had the largest effect on the equivalent strain of the tubes, followed by the angle of attack and the feed ratio. These results provide some guidance for the manufacture of high-performance bimetallic composite tubes by rotary ring spinning.

Fabrication of AA1050/CP-Cu Bimetallic Tubes using Parallel Tube-Shaped Channel Angular Pressing Technique and Assessing its Mechanical Properties and Microstructure

Fabrication of AA1050/CP-Cu Bimetallic Tubes using Parallel Tube-Shaped Channel Angular Pressing Technique and Assessing its Mechanical Properties and Microstructure

Hysteretic behavior of concrete-filled bimetallic tube (CFBT) columns under combined loads

The experimental results on the hysteretic behavior of concrete-filled stainless steel (outer)-carbon steel (inside) bimetallic tube (CFBT) columns are presented in this paper. Five CFBT column specimens and one conventional concrete-filled carbon steel tube (CFST) column specimen were tested under combined constant axial compression and reversed lateral loads, and the main test parameters included the axial compression ratio and strength of the infilled concrete. The experimental results showed that, the failure characteristic of CFBT columns was close to that of CFST columns with the same parameters, which was featured by local outward buckling of the steel tube accompanied by concrete crushing at the corresponding location. No delamination of the bimetallic tube was observed during the whole loading process. The load versus deformation curves for all the specimens exhibited a plump shape without obvious pinching phenomenon, indicating favorable load-carrying and energy dissipation capacities. During loading, the strength of CFBT columns showed a stable degradation rate with the increase of lateral displacement. Both the yield load and peak load of CFBT columns tended to increase as either the axial compression ratio or concrete strength increased. The Eurocode 4 gave acceptable predictions of the strength of CFBT columns under combined loads.

Investigation of AL/CU Bimetallic Tube Cladding Process by Severe Plastic Deformation

Investigation of AL/CU Bimetallic Tube Cladding Process by Severe Plastic Deformation

CONTACT THERMAL RESISTANCE BETWEEN THE FIN AND PIPE-BASE FOR COMPOSITE HEAT TRANSFER SURFACES

Experimental setup for investigation of contact thermal resistance (CTR) of composite heat-exchange tube, made of flat-oval steel tube – base and aluminum fins, which are connected to the base by means of contact welding, has been developed. By direct measurement, the СTR values for a composite heat exchanger tube are compared to the CTR values for three types of bimetallic tubes with rolled aluminium fins: carbon steel 20 base tube, stainless steel 1X18H10 base tube and brass base tube. It is established that for a composite heat-exchange tube the mean thermal resistance of contacting surfaces doesn't depend on the density of supplied heat flow and makes constant value Rk = 2,75×10–6 Km2/W, that is practically equal to zero for engineering calculations and it is possible to neglect it. For composite heat-exchange tube the application of contact welding technology makes it impossible to deteriorate thermal contact between monorail and tube due to temperature fluctuations in the process of operation of heat-exchange apparatuses. The results obtained show that the composite surface with welded aluminium monofin has two orders of magnitude lower CTR than the heat exchange surfaces made of widely used bimetallic tubes of all known types. This provides the highest heat transfer coefficient.

Efficiency of Bimetallic Ribbed Tube Bundles in Forced Convection Conditions

Efficiency of Bimetallic Ribbed Tube Bundles in Forced Convection Conditions

Simulation and experimental research on 316L liner of bimetal composite pipe with eddy current testing

Conventional magnetic flux leakage technology is unable to identify the stainless steel-lined defects of bimetallic composite pipe. In this paper, the in-line inspection technology of a 316L liner based on the eddy current flaw detection principle is studied with the aim of solving this problem. A printed circuit board (PCB) coil is designed and parameters such as the external diameter, the number of turns, the number of layers and the shape of the eddy current testing coil are determined. The impedance changes that occur under the influence of different factors of the coil are analysed according to finite element simulation. The contribution of each influencing factor during eddy current testing is investigated to optimise the coil parameters and excitation parameters. An eddy current flaw detection model for the stainless steel liner is finally established and numerical calculation is carried out on the impedance response of the defect, which is detected by parameterised scanning with the coil swept. The coil impedance is obtained under the ideal state and then verified by the experimental tests. The results show that the eddy current array testing coil has good applicability in the detection of surface defects on the stainless steel liner, which can provide references for the development of a bimetallic tube composite probe.

Full-cross-section deformation characterization of Cu/Al bimetallic tubes under Rotary-Draw-Bending based on physics-driven B-spline curves fitting

It is difficult to detect the inner layer of the bimetallic tube and to describe its full-cross-section deformation, which negatively affects its verification and utility. To tackle this issue, a novel theory is proposed for fitting the full-cross-section deformation characterization of Cu/Al bimetallic tubes under Rotary-Draw-Bending. The cross-section profiles on the bending outside are fitted by the physics-driven B-spline curves. The geometric characteristics and the bending principles are set as the physics information and drive the design of the control vertices of the fitting B-curves. The interlaminar shape inheritance of the bimetallic tube is implemented by the same position angle of the corresponding control vertices. The cross-section profiles on the bending inside are fitted by the regular curves considering the elongation percentage. The comparison between the theoretical profiles and the experimental profiles shows remarkable agreement. The average circumferential errors of the theoretical profiles are within 1.82%, far smaller than the errors of the traditional ovalization profiles. Additionally, the representative parameters of full-cross-section deformation are differently affected by the wall-thickness. The wall-thinning of the outer layer and inner layer usually shows an opposite tendency when the wall-thickness varies.

Fabrication of Al/Mg Bimetallic Thin-Walled Ultrafine-Grained Tube by Severe Plastic Deformation

Multilayer composites have recently attracted considerable attention due to their ability to take advantage of the benefits of various metallic materials simultaneously. The present study is the first to use parallel tubular channel angular pressing (PTCAP) as a severe plastic deformation method to fabricate a bimetal Al/Mg tube. This process was applied on commercially pure aluminum along with an AM60 magnesium alloy at the temperature range of 250-400 °C. According to the microstructural and mechanical tests, there is a strong bond between layers besides the grain refinement after the process. Additionally, microhardness examinations showed that there is an excellent homogeneity in addition to the dramatic increase in the hardness of bimetallic PTCAP processed Al/Mg tube. Scanning electron microscope and energy-dispersive x-ray spectroscopy analyses in the interface between the layers and also the results of the shear strength test showed that by increasing the temperature, the diffusion rate at the interface increases. For instance, the significant bonding strength of 30 MPa was achieved after the PTCAP specimen at 400 °C. Therefore, these investigations substantiate that the PTCAP process can be used as an appropriate cladding technique for obtaining simultaneous severe plastic deformation microstructures and sufficient bonding strength in the production of bimetallic tubes.

ТЕХНОЛОГИИ ИЗГОТОВЛЕНИЯ БИМЕТАЛЛИЧЕСКИХ ТРУБ

The aim of the study was to develop a cost-effective technological process for manufacturing axisymmetric parts of the "Bimetallic tube" type with an internal cooling circuit. The article proposes to consider the technological process of cold volumetric stamping, which includes the most rational, from the point of view of resource saving, operations - reduction of a billet made of low-carbon structural steel and burnishing of a billet with high resistance to intercrystalline corrosion from low-carbon stainless steel. The product obtained by experimental technology, which is a bimetallic pipe with an internal cooling circuit. The developed computer model of the technological process made it possible to obtain a competitive product that has a wide range of applications. In the course of the work, an experimental study was also conducted, which confirmed the results of computer analysis. The absence of rubber seals in the production of the heat exchanger allows it to be used for aggressive environments in the chemical, oil and gas industry with temperatures from minus 40 to 300 degrees Celsius. The technology will increase the working pressure of the heat carriers to a value of at least 2 MPa. Due to the small cross-section of the cooling circuit, it is possible to achieve high coolant speeds, and the multi-entry circuit allows for a larger volume of coolant. At the same time, the efficiency of the heat exchanger increases by 5% compared to the sectional heat exchanger in its classic design. Quality characteristics: low metal consumption, strength, reliability, safety, ease of installation, maintainability. One of the main advantages of the technology is the high surface quality of the product (Ra 1,6), which guarantees the turbulent flow of the coolant. The efficiency of the heat exchanger according to the strictest estimates and for the most unfavorable conditions is 86.6%.

Full-Cross-Section Deformation Characterization of Cu/Al Bimetallic Tubes Under Rotary-Draw-Bending Based on Physics-Driven B-Spline Curves Fitting

Full-Cross-Section Deformation Characterization of Cu/Al Bimetallic Tubes Under Rotary-Draw-Bending Based on Physics-Driven B-Spline Curves Fitting

Numerical study on behavior of eccentrically loaded concrete-filled bimetallic tubes

The concrete-filled bimetallic tubular (CFBT) member studied in this paper comprises a stainless steel/carbon steel bimetallic tube infilled with core concrete. It has the advantages of enhanced mechanical property, good corrosion resistance and cost effectiveness. A finite element analysis (FEA) model is established to investigate the performance of eccentrically compressed CFBT short columns with a circular cross-section. The model is verified against the experimental results presented in a companion paper. The comparisons show that the FEA model reproduces reasonably well the failure mode, load-deformation response, ultimate strength and strain development of the composite member. The validated model is then used to further investigate the performance of eccentrically loaded CFBT members, followed by a wide-range parametric analysis. Results indicate that the two layers of the bimetallic tube attain their ultimate strength before the concrete core. The material strength shows a major effect on the ultimate strength of CFBT members, whilst the coefficient of friction for the interface between different materials and the strain-hardening exponent of stainless steel have a minor influence. Finally, the applicability of various design codes is explored and the comparisons show that the load-carrying capacity predicted by AISC360-16 is conservative, whilst Eurocode 4 and DBJ/T13-51–2010 produce relatively accurate predictions.

Influence of the purity of water-oil emulsions on the degree of contamination of the surfaces of finned tubes of air coolers

The existing technologies for cleaning finned bimetallic tubes of air-cooling devices and methods for control the contamination of the surface of aluminum alloys are analyzed in order to identify the disadvantages of the cleaning methods used in the production of finned tubes. A quantitative rapid assessment of the finned surface cleaning is obtained. Keywords: finned surface, contamination, cleaning, alkaline solution, finned bimetallic pipes, air cooler, control. alex@bgutmo.ru