Parallel Tubular Channel Angular Pressing Research Articles

Study of Hydroxyapatite-coated High-strength Biodegradable Magnesium-based Alloy in Repairing Fracture Damage in Rats.

Hydroxyapatite (HA) coating can improve the degradation rate and biological activity of metallic implants. This study aimed to fabricate a hydroxyapatite-coated ultrafine-grained biodegradable WE43 magnesium (HA/UFG-WE43 Mg) implant for repairing bone fractures. A hybrid approach, including parallel tubular-channel angular pressing (PTCAP) and physical vapour deposition (PVD) magnetron sputtering, was employed. The HA/UFG-WE43 Mg samples were tested in terms of their physicochemical and biological properties. The processed tubes exhibited ultrafine structures and the uniformity of microstructures improved following the two-pass PTCAP. The phase composition of the coating formed on UFG-WE43 Mg implant at 250 W for 90 min after heat treatment at 500°C for 60 min confirmed the presence of the HA characteristic peaks. Rat skeletal muscle cells were inoculated on the specimens and cultured for 1, 2, 6, 12, and 24 h, followed by evaluation of cell adhesion and morphology. The growth rates of cells were examined by the Cell Counting Kit8 (CCK-8) and cell survival was observed after 3 days of culture by fluorescence microscopy. The concentration of Mg ions in the blood of rats on 1, 3, 5, 7, and 15 days showed a reduction in Mg concentration after deposition of HA. Combination of PTCAP processing followed by surface modification led to tibial fracture healing, and histological analysis of implanted areas demonstrated an efficient biodegradation of the implanted material and a moderate inflammatory reaction.

Influence of Parallel Tubular Channel Angular Pressing (PTCAP) Processing on the Microstructure Evolution and Wear Characteristics of Copper and Brass Tubes.

The influence of the number of passes and the tube materials on the microstructural evolution, mechanical properties, and wear behavior of Cu and brass tubes after parallel tubular channel angular pressing (PTCAP) was investigated. The grain size decreased to final grain sizes of 138.6 nm and 142.7 nm, after PTCAP of the Cu and brass tubes was conducted in up to 4 and 2 passes, respectively. PTCAP contributes to obtaining an ultra-fine grain (UFG) microstructure, with a mixture of different grain sizes that conferred high hardness. The present results indicate the superior wear resistance of Cu and brass PTCAP tubes, relative to Cu and brass samples that were previously deformed by different severe plastic deformation (SPD) processes. The wear mechanism of the Cu tubes changed from delamination and cracks with a high degree of adhesive wear before PTCAP into a combination of adhesive and abrasive wear, with a decrease in the presence of oxygen content after the PTCAP procedure. The wear mechanism also changed from a combination of adhesive and abrasive mechanisms into abrasive ones with the absence of oxygen after the PTCAP of brass tubes.

Parallel Tubular Channel Angular Pressing (PTCAP) Processing of the Cu-20.7Zn-2Al Tube.

Commercial Al-brass tube was successfully processed by Parallel Tubular Channel Angular Pressing (PTCAP) in 2 passes under an imposed strain of 1.49 per pass. The effect of the number of PTCAP passes on the microstructure and the mechanical properties (hardness, tensile, and wear mass loss) of the Al-brass tubes was fully investigated. The average grain size of the as-received tube decreased to 1.28 μm after up to two passes of PTCAP with a mixture of ultrafine grain (UFG) and coarse grain (CG). The annealed tubes’ tensile strength and Vickers hardness increased by 237.65% and 175.6%, respectively, after two passes. In addition, a ductile fracture occurred with a clear necking. The fracture surface morphology indicated an apparent decrease in dimple size after PTCAP processing, combined with a decrease in ductility. Moreover, the wear mass loss decreased with increasing number of PTCAP passes due to the decrease in the grain size, and the increase of the hardness of the tubes was enhanced after PTCAP processing.

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.

Finite Element Simulation of the Parallel Tubular Channel Angular Pressing Process for Al–Cu Bimetallic Tube with Experimental Verification

Finite Element Simulation of the Parallel Tubular Channel Angular Pressing Process for Al–Cu Bimetallic Tube with Experimental Verification

Mechanical properties modeling of severely plastically deformed biodegradable ZK60 magnesium alloy for bone implants

The effectiveness of magnesium (Mg) alloys to improve the capability of bone tissue generation may be severely diminished if the required mechanical properties are not provided. Here, the effort is directed to model the mechanical performance of severely plastically deformed biodegradable ZK60 Mg alloy in bone regeneration protocols. For this purpose, the effects of parallel tubular channel angular pressing (PTCAP) on yield strength (σ YS ), ultimate tensile strength (σ UTS ), and elongation to failure (δ) were addressed. Given the multifaceted variables of the PTCAP with nonlinear interactions, a precise determination of the mechanical properties requires a large number of experiments. Therefore, gene expression programming (GEP) and genetic programming (GP) models were proposed to achieve appropriate combinations of mechanical properties for bone implant purposes based on a rational hypothesis that for correlation coefficient (|R|) higher than 0.8, a strong correlation is established between the predicted and measured values. The results verified that the highest mechanical performance was achieved at the second pass of PTCAP, thus has a great potential to be the most promising candidate for biodegradable implant material. Besides, the proposed models were capable of precisely predicting the mechanical performance of the SPD-processed biodegradable ZK60 Mg.

Experimental and Modelling Study of Ultra-Fine Grained ZK60 Magnesium Alloy with Simultaneously Improved Strength and Ductility Processed by Parallel Tubular Channel Angular Pressing

Ultrafine grained ZK60 magnesium (UFG–ZK60 Mg) tubes were successfully fabricated by a parallel tubular-channel angular pressing (PTCAP) process. The number of pass effects on the phase composition, microstructural features and mechanical properties were examined. Also, two types of Artificial Neural Network known as Radial Basis Function (RBF) and Multi-Layer Perceptron (MLP) were employed to accurately estimate mechanical behavior of the PTCAP-processed ZK60 Mg alloy. The results showed that all the processed tubes had more refined microstructure with ~ 7 to 0.9 μm grain sizes, which consist of an average crystallite size between 68 ± 8 and 51 ± 8 nm, compared to the as-received specimen with a mean grain size of ~ 90 μm. Similar XRD profiles were achieved following different PTCAP passes, however, some discrepancies were observed as the number of passes increased, which corroborated the structural changes during the PTCAP process. The microscopic observations also revealed the microstructural changes by increasing the PTCAP passes. The hardness of the processed tubes increased with the number of PTCAP passes, from 77 ± 2 HV for the unprocessed alloy to a maximum of 111 ± 2 HV at three PTCAP passes. The PTCAP process increased not only mechanical strength but also the ductility of the processed tubes, where the highest yield strength (σYS = 320 MPa), ultimate tensile strength (σUTS = 397 MPa) and elongation to failure (δ = 14%) values were obtained at the second pass of PTCAP. However, with increasing number of PTCAP passes to three, δ reached 4% and σYS and σUTS decreased by 31% and 11%, respectively. Findings from the neural based-predictive models indicated that both RBF and MLP can be employed for accurately estimating the mechanical properties of the PTCAP-processed ZK60 Mg alloy.

Lubrication performance of rapeseed oil-based nano-lubricants in parallel tubular channel angular pressing process

Due to the biological risks of using the conventional lubricants, the vegetable oils have been considered nowadays. Besides, to improve the tribological properties of the vegetable oils in various applications like metal forming processes, nanoparticles have been used as additives. This research evaluated the lubrication performance of the Al2O3 and TiO2 nanoparticles dispersed in rapeseed oil during the parallel tubular channel angular pressing (PTCAP) process. The experimental PTCAP tests have been fulfilled under three lubrication conditions and the comparison between the PTCAP processed tubes has been performed in terms of the maximum forming force, surface roughness, and microhardness. The experimental results indicate that adding the mentioned nanoparticles has caused at least a 50% reduction in the maximum deformation load. Moreover, a remarkable decrement in the surface roughness of the formed tubes has been obtained.

Enhanced Hot Tensile Ductility of Mg-3Al-1Zn Alloy Thin-Walled Tubes Processed Via a Combined Severe Plastic Deformation

In the current study, combined parallel tubular channel angular pressing (PTCAP) and tube backward extrusion (TBE), as a recently developed severe plastic deformation (SPD) method, were applied at 300 °C on a commercial Mg-3Al-1Zn alloy tubes to achieve an ultrafine grained structure. Then, the microstructure, hardness, tensile properties, and fractography evaluations were done at room temperature on the SPD-processed samples. Also, to study the hot tensile ductility of the SPD-processed samples, tensile testing was performed at an elevated temperature of 400 °C, and then, the fractured surface of the tensile samples was studied. It was observed that a bimodal microstructure, with large gains surrounded by many tiny ones, was created in the sample processed by PTCAP followed by TBE. This microstructure led to reach higher hardness and higher strength at room temperature and also led to reach very high elongation to failure (~ 181%) at 400 °C. Also, the value of elongation to failure for this sample was ~ 14.1% at room temperature. The fractographic SEM images showed the occurrence of predominately ductile fracture in the samples pulled at 400 °C. This was mostly due to the nucleation of microvoids and their subsequent growth and coalescence with each other.

Hot tensile deformation behavior of Mg-Zn-Al magnesium alloy tubes processed by severe plastic deformation

In the current study, parallel tubular channel angular pressing (PTCAP), as a severe plastic deformation (SPD) method, was applied on a commercial pre extruded Mg-3Al-1Zn (AZ31) alloy tubes at 300 °C to achieve a fine-grained (FG) structure. To study the deformation behavior, tensile testing at different temperatures of 25 °C, 350 °C, 400 °C, and 450 °C was done on the samples processed by multi-pass PTCAP. Also, the strain rate sensitivity exponent (m) is measured for the four-pass PTCAP processed tube, at 350 °C, 400 °C and 450 °C and strain rates of 10−2, 10−3 and 10−4 1/s. The average value of m coefficients was ∼0.3. A higher elongation to failure of ∼281% was achieved at a higher temperature of 450 °C and a lower strain rate of 10−4 1/s, due to grain boundary sliding as a dominant deformation mechanism. After the first pass of PTCAP a bimodal microstructure, with large gains surrounded by many small ones, was observed. The grain refinement and homogeneity of the microstructure was enhanced by applying subsequent passes of PTCAP. Vickers microhardness measurements show that by more grain refinement caused by applying for more PTCAP passes, the value of hardness increased. Fractographic SEM images revealed that predominately ductile fracture occurred in all evaluated samples.

Microstructure and mechanical properties of fine-grained thin-walled AZ91 tubes processed by a novel combined SPD process

A combination of parallel tubular channel angular pressing (PTCAP) and tube backward extrusion (TBE) as a novel combined severe plastic deformation (SPD) was applied on AZ91 alloy to produce ultrafine-grained (UFG) thin-walled tubes. The effects of combined SPD process were investigated on the microstructure refinement and mechanical properties. Also, hydro-bulge test was carried out to reveal the mechanical properties. The results showed a notable increase in ultimate strength, yield strength and microhardness of the thin-walled UFG tube were achieved compared to that from PTCAP process. A remarkable grain refinement achieved. Applying three-passes-combined process refine the grain size to 8.8 \(\upmu \hbox {m}\) from an initial value of \(\sim \)150 \(\upmu \hbox {m}\). For one pass- and two passes-processed thin-walled tubes, it was about 12.4 and 9.8 \(\upmu \hbox {m}\), respectively. Yield and ultimate strengths were increased notably to 150 and 354 MPa for 2P+TBE tube, from the initial values of 86 and 166 MPa, respectively. The maximum microhardness was increased to about 105 Hv for the 2P+TBE tube from the initial value of 56 Hv. Hydro-bulge test showed that the bursting pressure increased to 246 bar for 2 passes-thin-walled tube from the initial value of 160 bar. It was 220 and 195 bar for 1 pass- and 3 passes-thin-walled tubes, respectively.

Microstructure and homogeneity of semi-solid 7075 aluminum tubes processed by parallel tubular channel angular pressing

Semi-solid processing is a new developing technology for the fabrication of intricate parts at low temperatures in comparison with conventional casting routes. In this research, a parallel tubular channel angular pressing (PTCAP) was used as a pre strain-inducing process, and the influence of the number of PTCAP passes and semi-solid heating parameters on the microstructural characteristics of Al7075 tubes was investigated. The results demonstrated that PTCAP process could successfully be used as a best pre-straining method for tubular samples showing semi-solid microstructures. As the temperature is increased, the solid particle size first decreased, then increased, and gradually became more spherical. The appropriate condition for the subsequent semi-solid forming process was gained at reheating temperature of 620 oC. The suitability of this temperature was confirmed by the uniform distribution of grains. The grain size and shape factor both increased along with increasing the holding time. The distribution of the solid particles was strongly dependent upon the holding time and became uniform as the holding time increased. Comparison of the grain size and shape factor between ECAPed and PTCAPed samples revealed a high capacity of the PTCAP process as a strain-inducing stage. Also the two-pass PTCAP samples exhibited higher hardness than one-pass treated samples in the semi-solid state.

Analysis and Simulation of Parallel Tubular Channel Angular Pressing of Al 5083 Tube

Severe plastic deformation (SPD) is divided to a number of branches. One of the most important branches of SPD of tube materials is parallel tubular channel angular pressing (PTCAP). The PTCAP process is more complicated than another SPD process for metal tubes. The PTCAP process includes two half cycles for obtaining the desired product. There are some factors, which affect the PTCAP process. For instance, deformation ratio, clamping force, channel angles, and curvature angles. In this paper, the PTCAP process for aluminum alloy (Al 5083) was simulated through the finite element ABAQUS software in order to investigate the effect of die parameters. Thus, the influences of deformation ratio, channel angles, and curvature angles on the PTCAP process were examined numerically. In addition, to verify the finite element method (FEM) results, the PTCAP process was done experimentally. To some extent, good conformity was observed between the FEM calculations and experimental results.

Hot deformation behavior of Mg-Zn-Al alloy tube processed by severe plastic deformation

Abstract In the current study, severe plastic deformation (SPD) was applied on a commercial Mg-3Al-1Zn alloy tubes via parallel tubular channel angular pressing (PTCAP) route. Different passes of PTCAP process were applied, and microstructure, hardness and tensile properties at the room, and elevated temperatures were evaluated. The results showed that bimodal microstructure appeared and led to AZ31 alloy represented higher hardness, higher strength with a reasonable elongation at room temperature. Similarly, very high elongation to failure was achieved at a higher temperature. The increase in the number of SPD passes up to two, leads to increasing the ductility up to 263% at 400°C. Then, an increase in the number of PTCAP passes to three, leads to decrease in the ductility as the results of formation of microvoids when SPD processing at higher equivalent strains without a sufficient hydrostatic compressive stress. Relatively ductile fracture mode was also occurred in all samples.

Nano-mechanical properties and microstructure of UFG brass tubes processed by parallel tubular channel angular pressing

The production of the ultrafine-grained brass tubes was carried out by multi-pass parallel tubular channel angular pressing (PTCAP) as a severe plastic deformation process. In addition to that, the microstructural and nano-mechanical features were investigated by EBSD and Nanoindentation for 0, 1, and 3 passes in a comparable mode. The elastic-plastic and micro scratch behavior were analyzed to show the enhanced features. Based on the obtained results, Young’s modulus and hardness of the specimens shifted to 1.62 and 1.7 times of the coarse-grained counterpart after the third pass respectively. The effects of the number of passes on the grain refinement were also investigated to detect the applied changes through each step of the PTCAP experimental procedures. Moreover, based on the obtained results from EBSD, the grain size of 1 and 3 pass samples were refined to 780 and 590 nm from its initial size of 75 µm. The fraction of the high-angle grain boundaries was increased from 30% in pass 1 to 66% in pass 3 of the PTCAP process.

Hot tensile deformation and fracture behavior of ultrafine-grained AZ31 magnesium alloy processed by severe plastic deformation

Parallel tubular channel angular pressing (PTCAP) process as a novel intense plastic deformation method was applied to an AZ31 magnesium alloy tubes to achieve an ultrafine grained (UFG) structure. Tensile tests at different temperatures of 25°C, 350°C, 400°C and 450°C were done on UFG AZ31samples processed by multipass PTCAP process. The results showed that the second passes PTCAP processed specimen exhibits the best elongation of about 263% at a temperature of 400°C. Fractured tensile samples were metallurgically characterized to analyze the fracture mechanism. The result indicated a decreasing trend in the average grain size along the gripper section to failure tip of the fractured UFG sample. However, the hardness increases from gripper region to the end of gauge region near the fracture tip. However, at the fracture tip, hardness collapsed because the cavity and microvoids formed in this area during tensile deformation. Fractographic SEM images illustrated the mix ductile and brittle fracture modes at tensile temperatures of 350°C and 450°C. Though, completely ductile fracture mode with distinguishable dimples was seen at the UFG sample fractured at 400°C.

Evaluation of Hot Tensile Behavior of Fine-Grained Mg–9Al–1Zn Alloy Tube Processed by Severe Plastic Deformation

In the present study, parallel tubular channel angular pressing (PTCAP) process was implemented to as cast Mg–9Al–1Zn magnesium alloy tubes via different number of passes at 300 °C. Mechanical properties and microstructure evolution of the tubes were investigated at room and elevated temperatures. The results showed that an increase in strain leads to a higher strength, hardness, and elongation at room temperature. A significant grain refinement was achieved. It was decreased to 4 µm for a third pass processed tube from an initial value of 150 µm. Strength increased notably to about 92 % after the second pass PTCAP process. Increase in the strength after first pass PTCAP was 56 %. Elongation relatively increased at room temperature, too. Microvoids and microcracks appeared in the third pass processed specimen. This led to a loss in strength and elongation in comparison with first and second pass processed samples. Two pass processed sample revealed ~178 % ductility in 400 °C tensile test. Hardness increased by about 77 % after third pass PTCAP process. The result of the mechanical properties and the microstructure were consistent with each other.

Evaluation of the microstructure and mechanical properties of the ultrafine grained thin-walled tubes processed by severe plastic deformation

In this paper, ultrafine-grained (UFG) Cu-Zn tubes were processed via multi-pass parallel tubular channel angular pressing (PTCAP) process, and microstructure, mechanical properties along the axial and peripheral directions were evaluated. Mechanical characterizations were done using uniaxial tension test along both the axial and peripheral directions and biaxial bulging tests. The hydro-bulging test was used to measure the bursting pressure of UFG tubes. The results present that the UFG and nanostructured tubes achieved form PTCAP process exhibit excellent pressure bearing capacity in comparison with the coarse-grained (CG) counterparts. Also, the bursting pressure of the UFG tube was remarkably increased to 93 MPa just after the first pass of PTCAP process from 43.3 MPa for the CG one. It was 88 MPa and 81.3 MPa for second and third passes PTCAP processed tube. Important reasons for this behavior were both significant grain refinement and severe mechanical anisotropy results from texture evolution after PTCAP processing.

The Effects of the Multi-pass Parallel Tubular Channel Angular Pressing on the Microstructure and Mechanical Properties of the Cu–Zn Tubes

In this study, ultra-fine grained (UFG) Cu–Zn tubes were produced by parallel tubular channel angular pressing (PTCAP) process and the effects of the number of passes on the microstructure, mechanical properties and fracture behavior were investigated. The results showed that the yield and the ultimate strengths of the processed UFG tube increased about four and two folds compared to the coarse grain counterparts due to grains refinement. The notable increase in the strength achieved after the first pass of the PTCAP process and further passes of the process only have a minor effect on the tube properties which may be due to the grain size saturation. However, the tube ductility reduced drastically after the PTCAP processing. Hardness of the PTCAP processed tube was increased compared to the annealed one according to Hall–Petch relationship which reports the hardness in terms of grain size. The strength, hardness and ductility were decreased after two passes PTCAP as a result of the formation of microvoids during the further straining through three passes. Microstructural investigations show a notable decrease in the grain size.

Microstructure and Mechanical Properties of Ultra-fine-Grained Al-Mg-Si Tubes Produced by Parallel Tubular Channel Angular Pressing Process

In the present work, commercial Al-6061 alloy tubes were processed via multi-pass parallel tubular channel angular pressing (PTCAP). The effects of the number of passes on grain refinement and mechanical properties were investigated. The microstructural evolution was characterized using electron back-scattered diffraction (EBSD) and scanning electron microscopy. The mechanical properties were evaluated using tensile tests and hardness measurements. The EBSD analyses presented that the elongated subgrains or grains with ~800 nm in size and a high fraction of low-angle grain boundaries were formed after two PTCAP passes. After four passes, the elongated subgrains have transformed to almost equiaxed grains with ~400 nm in size and high-angle grain boundaries. Microhardness of the processed tube increased from 38.9 to 63.4 HV (~63 pct) after three PTCAP passes. An increase in the number of PTCAP passes after three passes has no more effect on the microhardness. Yield and ultimate tensile strength were increased by 2.1 and 1.6 times, respectively, after four PTCAP passes (e ~6.4) compared to the annealed sample. Ductile fracture with an extensive necking zone and many big dimples occur in the annealed sample, while fine dimples and limited ductile fracture features were observed in the ultra-fine grained PTCAP-processed samples.