Hot Extrusion Process Research Articles

Effect of structure and phase composition on the physical and mechanical properties of hot extruded titanium alloy Ti–3Al–2.5V tubes

This study investigates the impact the hot extrusion process variables on the physical and mechanical properties of Ti–3Al–V alloy The research examines four tube segments extracted from various hot-extruded tubes of Ti–3Al–2.5V alloy, with an outer diameter (OD) of 90 mm and a wall thickness of 20 mm. The manufacturing process involves expanding sleeves with a horizontal hydraulic press to achieve an OD of 195 mm, followed by heating to 850–865 °C prior to extrusion. The tube segments are labeled as 1, 2, 3, and 4, corresponding to their order of production. Our findings demonstrate that an increase in the number of extrusions in the α + β area from tube 1 to tube 4 leads to a reduction in the primary α-phase volume fraction and an increase in the β-transformed structure volume fraction. These changes are attributed to the higher final extrusion temperature resulting from more intense deformation heating during hot tooling (die and mandrel) processes. Additionally, elevating the final extrusion temperature from tube 1 to tube 4 leads to a notable decrease in the residual β-solid solution volume fraction and a reduction in the “sharpness” of the α-phase tangent-oriented texture. The alterations in the structural and phase state of the alloy from tube 1 to tube 4 are found to influence the contact modulus of elasticity and microhardness. These identified relationships can be utilized to optimize the process variables for the extrusion of multiple Ti–3Al–2.5V alloy tubes.

Analysis of processing map and parameters optimization during hot extrusion of 17 vol.% SiCp/2009Al composite

Hot extrusion process can improve the mechanical properties of materials. However, due to the presence of SiC particles, SiCp/Al composites are prone to fracture damage in the extrusion process. To determine the optimal processing parameters, the processing maps of 17 vol.% SiCp/2009Al composite were established using power dissipation rate and Murty instability criterion. Furthermore, taking aluminum canning into consideration, a three-dimensional macroscopic hot extrusion finite element model of SiCp/Al composite was constructed. The influences of initial temperature, canning morphology and canning thickness on extrusion properties were predicted, and verified by comparison of processing maps and experiments. The optimal extrusion parameters for SiCp/2009Al composite are located within the window of temperature, 450–475 °C and strain rate, 0.001–0.004 s−1 or 0.6–1 s−1. Additionally, the properties of the SiCp/Al composite can be greatly improved by hot extrusion with a suitable canning. Of these, the half canning finish the extrusion task faster, but the extrusion properties under the bottom canning are the best. When the ratio of the canning thickness to the diameter of the workpiece is about 0.17, the effective stress, strain and damage are minimum. The work performed in this research, for the first time, provides quantitative evaluations of process parameters on the hot deformation of SiCp/Al composite, which enables to provide useful guides for hot extrusion parameters selection of SiCp/Al composite.

Fabrication of hypereutectic Al–Si alloy with improved mechanical and thermal properties by hot extrusion

Silicon phase in hypereutectic AlSi powders appears as primary Si and eutectic Si. Due to the poor thermal stability of eutectic Si, the material suffers from pores, stress concentration and dislocation packing during hot extrusion process, resulting in low density and poor thermal properties. In order to eliminate the eutectic Si, a heat treatment is conducted on Al20Si powders before hot extrusion. Because of the Ostwald ripening effect, the eutectic Si and dislocations in the powders are replaced by isolated Si lumps and a clear Al matrix. As a result, the formability and thermal properties of the material are greatly improved. The extruded samples made from the treated powder present high relative densities 99.7–100%, ultimate tensile strength (UTS) 167–170 MPa, elongations 8.8–10.8% and thermal conductivities (TCs) 191–195 Wm−1 K−1 and low coefficient of thermal expansions (CTEs) 13.8–14.5 × 10−6/K. The excellent mechanical and thermal properties are attributed to the elimination of eutectic Si from the treated powders and as-extruded alloys. In addition, hot extrusion introduces in-situ Al2O3 in the Si surface, Al grain boundary and Al grains, which is beneficial to reducing and stabilizing the CTE of the material. Moreover, it hinders Ostwald ripening and thus growth of the Si particles during the service of the material.

An Detailed Overview on Mouth Dissolving Film

The present review aims to enlighten about a potential dosage form that is mouth dissolving films. Mouth dissolving film is a rapidly dissolving dosage form that dissolves in the mouth within a few seconds without the intake of water and is mainly used for pediatric and geriatric patients due to its flexibility and patient compliance. It is a potential dosage form for drugs having high metabolism and low bioavailability. Solvent casting, hot melt extrusion, solid dispersion, semisolid casting, rolling, and other processes can all be used to create mouth dissolving film, but solvent casting is the most popular due to its consistency and superior physical properties. Mouth dissolving film is evaluated for the following parameters like physical parameters and chemical parameters. The review sums up information on drug delivery by mouth dissolving films as a promising dosage form for delivering drugs to children and elderly patients, as well as information on its formulation considerations, preparation process, and evaluation criteria.
 Keywords: Mouth dissolving film, Buccal film, Improved patient compliance, Standard composition, Method of preparation, Evaluation

Simultaneous improvement on strength and conductivity of CrB2/Cu composites by inhomogeneous design

Inhomogeneous CrB2/Cu composites with 5 vol% CrB2, namely CrB2 concentrated in special areas rather than uniformly dispersed in the whole materials were prepared by powder metallurgy combined with hot extrusion process. Results show that obvious submillimeter-sized CrB2 rich-irregular regions or band structures can be observed on the vertical and parallel to extrusion directions, respectively. The inhomogeneous degree can be adjusted by using the ball milled CrB2-Cu composite powder with different sizes, and has big influence on the strength and electrical conductivity of the composites. When the size of composite powder is 425–850 μm, the best combination properties of strength (436 MPa) and electrical conductivity (82.84%) can be obtained. Compared with the conventional homogeneous with the same chemical composition, the strength increases by 89%, but the electrical conductivity only decreases by 6%. This work provides a new approach for material design, which can coordinate between strength-conductivity of Cu matrix composites, effectively.

Optimization of hot extrusion process parameters for 7075 aluminum alloy rims based on HyperXtrude

Aluminum alloy has the characteristics of light weight, high strength, corrosion resistance, easy forming, etc., and is widely used in manufacturing industry. The extrusion speed of aluminum alloy rim is not uniform, which affects the mechanical properties of the product. In order to solve these 1problems, the finite element analysis model of hot extrusion of aluminum alloy profiles was established in HyperXtrude software. The influences of different bar diameters, hot extrusion velocity, bar preheating temperature, die temperature and extrusion cylinder temperature on velocity difference and maximum extrusion pressure at the exit were analyzed. The results show that the designed hot extrusion rim die meets the requirements of strength and deformation, and the best extrusion process parameters of 7075 aluminum alloy rim profiles in improving profile quality and reducing energy consumption are obtained by Taguchi test gray correlation method.

Evaluation of microstructure and tensile properties of Mg–5Zn-xZr-yCa alloys

In this work, an attempt was made to study the synergetic effects of changes in alloying elements including Zr and Ca, as well as the hot extrusion process on the microstructure, texture, and mechanical properties of Mg–Zn-xZr-yCa (x= 0.2 and 0.8 wt %; and 0<y<2) alloy. To do so, a variety of tests (OM, SEM, EBSD, EDS, TEM, APT, hardness and tensile tests) were performed after sample preparation. It was shown that Ca/Zr ratio plays an essential role in modifying the microstructure and mechanical properties of the alloy. For Ca/Zr<1, the grains size was remarkably refined to 1.2 μm, the wrought texture was moderately weakened, and the mechanical properties were significantly increased to 429 MPa. However, for Ca/Zr>1 grain size was almost unchanged, the texture of hot-extruded alloys became more equiaxed after hot extrusion, and tensile strength decreased compared to with Ca/Zr=1. Microstructural analysis revealed that Zr-bearing phases (Zn22Zr and Zn39Zr5) and solute theory were the dominant mechanisms of grain refinement in the as-cast state. An atom probe tomography technique was utilized to assess the segregation of solute elements into the grain boundaries. It was shown that particle stimulated nucleation is not likely to be the main mechanism of texture weakening of extruded alloys; and the solute segregation into grain boundaries facilitates this phenomenon. Finally, it was seen that values of yield and ultimate tensile strengths of Mg–5Zn-0.8Zr-0.5Ca were 372 and 429 MPa, respectively.

Doped halloysite nanotubes as a nanocontainer for the fabrication of ciprofloxacin hydrochloride loaded 3D printed scaffolds

Burn injuries are considered to be the most catastrophic form of skin injury, with a slight risk of mortality. This type of injury has a significant negative impact on both individuals and health care system. The hollow nano-tubular structures of doped halloysite nanotubes (DHNTs) facilitate in loading a wide variety of active molecules and make a potential nanocarrier for the delivery of drugs. Coincidentally, the high mechanical strength, good biocompatibility, and hemostasis properties of DHNTs offer a new platform for the fabrication of scaffolds to promote faster wound healing activity. Ciprofloxacin hydrochloride (Cip HCl) was chosen as the model drug to control the bacterial proliferation at the site of injury. Therefore, the present study was aimed to design a customized drug loaded nano-polymeric scaffolds by three dimensional (3D) printing techniques for tissue engineered applications in pharmaceutical sciences. Cip HCl loaded DHNTs coated poly vinyl alcohol pellets were extruded for the preparation of filaments by the hot melt extrusion process, and the prepared filaments were further processed for the fabrication of 3D printed scaffolds by fused deposit modelling (FDM) technique. The pellets were free-flowing with a coating efficiency of 60.23 – 82.65%. Scaffold 1 (S1) presented an excellent porous structure, while scaffold 2 (S2) revealed a slight porous structure with the porosity of 60%. The average pore diameter for both scaffolds ranged from 50.82 ± 23 to 93.06 ± 52 μm. S1 expressed a conventional release pattern of 73.35% ± 0.02 within 2 h of the time profile, S2 evidenced an inaugural burst release of 42.84% ± 0.05 at 2 h, followed by a sustained release of 85.54% ± 0.17 up to 12 h. Thus the FDM technique proves to be an ideal approach for the design of drug nanofiller coated polymeric 3D scaffolds for personalized drug delivery systems in the arena of tissue engineering and pharmaceutical sciences.

Simulation of Cross Wedge Rolling and Hot Extrusion-Combined Forming Process for Axle Sleeve

In this paper, an axle sleeve is formed through a combined cross wedge rolling (CWR) and hot extrusion process, and the combined forming process is simulated via finite element analysis software Deform-3D. The forming mechanism is revealed by analyzing the stress and strain distribution, the temperature variation and the metal flow law of the workpiece during CWR and hot extrusion. Combined with CWR and hot extrusion forming experiments, the feasibility of a combined rolling and extrusion process to produce an axle sleeve is verified. It has been proven that the outer steps of the axle sleeve produced through the rolling extrusion composite process are well formed, the flange extrusion cavity is full, the metal streamline is continuous, the axis of the inner hole does not easily deviate, the product quality is good and the production efficiency is high.

Development and characteristics of a low rare-earth containing magnesium alloy with high strength-ductility synergy

In this study, we successfully developed a low RE containing Mg-3Y-2Gd-1Nd-0.5Zr (wt%) alloy with high strength-ductility synergy by combined processes of hot extrusion, hot rolling and ageing. This alloy exhibits an excellent strength-ductility balance (UTS of 345 ± 2.0 MPa, TYS of 301 ± 5.0 MPa and EL of 9.2 ± 1.9%), which is better than that of many Mg-RE wrought alloys with higher RE concentration and even comparable to that of 6061 Al wrought alloy. A long-range chain-like structure consisting of β′ phase, β H phase, β M phase and zig-zag atomic columns is observed for the first time in the studied alloy. The combined process of hot extrusion and hot rolling boosts the formation of deformed grains and low angle grain boundaries, and makes the deformed grains dominate in the alloy strengthening. Under this circumstance, the following ageing generates a novel heterogeneous structure comprising the long-range chain-like structure with broad interparticle spacing and the spacious precipitate-free zones in the deformed grains, which plays a key role in the concurrent strengthening and toughening of the alloy. The present study demonstrates that the deformed grains with long-range chain-like structures and precipitate-free zones is desirable microstructure for the low RE containing Mg alloys to achieve high strength-ductility synergy.

Influence of Laser Treatment Medium on the Surface Topography Characteristics of Laser Surface-Modified Resorbable Mg3Zn Alloy and Mg3Zn1HA Nanocomposite

In this study, a Mg3Zn alloy and a Mg3Zn1HA nanocomposite were fabricated through disintegrated melt deposition, followed by the hot extrusion process. The specimens were subjected to fiber laser surface modification in air and demineralized water (DM) medium to determine the influence of the laser treatment medium on the microstructure, microhardness, grain size, and surface topography. During the laser treatment, the samples under the water medium produced a lower surface roughness when compared with the air medium. The atomic force microscope (AFM) surface topography scan showed the presence of surface modifications caused by the presence of nanohydroxyapatite (nHA) in the matrix, resulting in a 367.4% and 632.4% increase in the surface roughness (Ra) in the Mg3Zn1HA nanocomposite when compared with the Mg3Zn alloy in water and air media, respectively.

Hot extruded Al5SiC-graphite composites: Effect of graphite on microstructure, flexural, compressive and wear resistance behavior

The Al5SiC and hybrid Al5SiC-graphite composites with 2 and 8 wt% of graphite were manufactured by a hot extrusion process. The starting material was in the form of powders. The effect of graphite on the microstructure, mechanical and tribological properties of Al5SiC composites was investigated. Extruded rods had a relative density greater than 97 %. The microstructure of hybrid composites was characterized by longitudinal stripes of reinforcement with its local agglomerations in the composite containing 8 wt% graphite. The Al5SiC composite exhibited the highest flexural strength (386 MPa) and compressive strength (642 MPa) and was distinguished by the lowest weight loss (0.00116 g). The addition of 8 wt% of graphite resulted in a significant deterioration of the flexural strength (269 MPa) and compressive strength (312 MPa) compared to the matrix material. The Al5SiC-8Cgr composite was characterized by the highest weight loss (0.01681 g) and the lowest friction coefficient (0.60) among tested materials.

POLYMORPHIC STABILITY EVALUATION OF DARUNAVIR AND RITONAVIR IN FIXED DOSE DRUG COMBINATION PRODUCT BY X-RAY DIFFRACTION AND DIFFERENTIAL SCANNING CALORIMETRY TECHNIQUES

Evaluation of polymorphism for active ingredients and its stability during manufacturing and storage is a critical task for pharmaceutical firms. For solubility enhancement of ritonavir, hot melt extrusion process was selected through conversion of commercially available crystalline form to amorphous. XRD method (with normal and slow scan) and DSC method was considered for polymorphic evaluation in tablet formulation comprising darunavir 800 mg and ritonavir 100 mg. Specificity and precision of XRD method was justified by no interference of placebo and 5.6% RSD, respectively. The observed correlation coefficient of 0.9991 and average recovery of 98.7% (range 91.5 to 105.1) depicts linearity and recovery power of developed method. Studied DSC method shows exotherm for ritonavir crystalline form II at 127.4 °C and darunavir ethanolate at 105.7 °C, which were specific and sensitive to assess polymorphic form of available drug substances in ritonavir blend as well as in tablet formulation during release and stability period.

Simultaneously improved electrical and mechanical performance of hot-extruded bulk scale aluminum-graphene wires

Aluminum-based alloys are highly sought after as lightweight alternatives in electric grid applications. Improving the electrical conductivity of aluminum alloys has the potential to increase the energy efficiency of power transport. The hot extrusion process was used to synthesize AA1100 alloy with low-cost reduced graphene oxide nanoparticles to manufacture ultra-conductive aluminum composites in this study. The effects of graphene content on the electrical and mechanical performance of the composites were evaluated. The macroscale AA1100/graphene wires demonstrated a 2.1% enhancement in electrical conductivity at 20 °C, while the ultimate tensile strength increased by 6.1%. A Zener-Hollomon model was used to confirm the in-process exfoliation of the agglomerated graphene nanoparticle feedstock into high electrical conductivity graphene-like flakes during extrusion. The graphene-like flakes may have provided high-velocity carrier pathways leading to the enhanced electrical performance of the alloy. Transmission electron microscopy at aluminum-graphene interfaces ensures the preclusion of detrimental carbide formation during composite synthesis while confirming the structure of graphene-like flakes. The in-process exfoliation provides an economically viable technique to produce bulk scale “graphinated” aluminum composites for advanced applications and this can also be applied more generally to other alloy systems.

Developing Mg-Gd-Dy-Ag-Zn-Zr Alloy with High Strength via Nano-Precipitation

A high-performance Mg-10Gd-4Dy-1.5Ag-1Zn-0.5Zr (wt.%, EQ142X) alloy was designed by multi-element composite addition in this work, obtaining a high yield strength (~396 MPa) and ultimate tensile strength (~451 MPa) after hot extrusion and ageing. The high strength is mainly related to fine grains and nano-precipitates, especially the latter. β' and γ″ nano-precipitation with high fractions are the main strengthening phases, leading to a strengthening increment of ~277 MPa. Moreover, the multi-element alloying in this study promotes the basal-prismatic network strengthening structure, composed of β' nano-precipitation with (1-210) habit planes, γ″ nano-precipitation with (0001) habit planes, basal plane stacking faults and 14H-long period stacking ordered phase. In addition, the dislocations and fine grains introduced by the hot-extrusion process not only accelerate the precipitation rate of nanostructure and thus improve the ageing hardening efficiency, but also facilitate the formation of more uniform and finer nano-precipitation. Thus, it is proposed that introducing nano-precipitates network into fine-grained structure is an effective strategy for developing high-strength Mg alloys.

Numerical simulation and experiment study on hot extrusion process of 18Ni (250) maraging steel large fan shaft for aero-engines

Numerical simulation and experiment study on hot extrusion process of 18Ni (250) maraging steel large fan shaft for aero-engines

Improved mechanical properties of mechanically milled Mg2Si particles reinforced aluminum-matrix composites prepared by hot extrusion

From the viewpoints of particle refinement and homogeneous distributions of reinforcing phase, this work proposed a novel method to prepare Al/Mg2Si composites. Mg2Si particles were synthesized by solid-state reactions of Mg and Si powder mixtures at a high temperature, and then refined by mechanical milling (MM) for 12–36 h. Subsequently, the MMed Mg2Si particles were incorporated into Al powder followed by hot extrusion for consolidation. The effect of milling time on microstructure and mechanical properties of the Al/Mg2Si composites was investigated. As the milling time increased, the average size of the Mg2Si particles in the composites became smaller, but the grain sizes of Al matrix remained almost unchanged. The hot-extrusion process was found to eliminate some particle agglomerations and promote size reduction and uniform dispersion of Mg2Si particles in the Al matrix. The elastic modulus, yield strength, ultimate tensile strength (UTS), and wear resistance of the composites increased by 8%, 14%, 8.5%, and 38.2%, respectively, with increasing the milling time from 12 h to 36 h, but the elongation decreased by 41%. Furthermore, the hot-extruded Al/Mg2Si composites exhibited high strength and ductility, for example, the UTS and elongation of the composites with 15 wt% Mg2Si particles MMed for 36 h increased by 43% and 91%, respectively, compared to conventionally cast Al/Mg2Si composites. The predicated elastic modulus by the Halpin-Tsai model is close to the experimental results. Moreover, the thermal mismatch strengthening is the dominate strengthening mechanism to improve the yield strength of the Al/Mg2Si composites.

High strength and plasticity TiBw/TA15 composites with a novel columnar network structure

In this paper, a novel columnar network structure reinforced TiBw/TA15 composites with excellent strength and high plasticity have been designed and prepared. To study the strengthening mechanism, the effects of the columnar network structure on the microstructure evolution and mechanical properties of the composites were investigated. The columnar network structure could effectively strengthen the grain boundary of the high temperature β phase and then enhanced the strength of the composites. At the same time, during the hot extrusion process, TiBw hindered the movement of dislocations and brought high distortion energy, which provided a favorable condition for dynamic recrystallization (DRX) of the matrix. DRX decreased the dislocation density, refined the grains, and then improved the plasticity of the matrix. Therefore, the effective combination of strength and plasticity was achieved in the composites.

The Effect of Sub- and Near-Critical Carbon Dioxide Assisted Manufacturing on Medical Thermoplastic Polyurethane.

Incorporating thermally labile active pharmaceutical ingredients for manufacturing multifunctional polymeric medical devices is restricted due to their tendency to degrade in the hot melt extrusion process. In this study, the potential of sub- and near-critical carbon dioxide (CO2) as a reversible plasticiser was explored by injecting it into a twin-screw hot melt extrusion process of Pellethane thermoplastic polyurethane to decrease its melt process temperature. Its morphological, throughput, thermal, rheological, and mechanical performances were also evaluated. The resultant extrudates were characterised using scanning electron microscopy, parallel plate rotational rheometer, differential scanning calorimetry, thermogravimetric analysis, and tensile testing. The process temperature decreased from 185 to 160 °C. The rheology indicated that the reduction in melt viscosity was from 690 Pa.s to 439 Pa.s (36%) and 414 Pa.s (40%) at 4.14 and 6.89 MPa, respectively. The tensile modulus in the elastomeric region is enhanced from 5.93 MPa, without CO2 to 7.71 MPa with CO2 at both 4.14 and 6.89 MPa. The results indicate that the employment of both sub- and near-critical CO2 as a processing aid is a viable addition to conventional hot melt extrusion and that they offer more opportunities for thermosensitive drugs to be more stable in the molten stream of Pellethane thermoplastic polyurethane.

High-ductility fine-grained Mg-1.92Zn-0.34Y alloy fabricated by semisolid and then hot extrusion

The combination of semisolid and hot extrusion processing was applied to refine the icosahedral quasicrystalline phase (I-phase) in an extruded Mg-1.92Zn-0.34Y(wt.%) alloy for the first time. The semisolid isothermal heat treatment transformed the micron-sized I-phase particles into nano lamellar eutectic (α-Mg + I-phase) with a lamellar spacing of ~86 nm. After subsequent hot extrusion at 250 °C, the nano lamellar eutectic phases were broken into uniformly dispersed nanoscale I-phase particles. What's more, the matrix microstructure was significantly refined with an equiaxed average grain size of 2.59 ± 0.81 µm, and an unusual texture component (most of the grains’ c-axis is parallel to the extrusion direction) was observed. The processed alloy exhibited a high tensile elongation to failure (EL) of 44 ± 2.6% with an ultimate tensile strength (UTS) of 258 ± 2.0 MPa and a tensile yield strength (TYS) of 176 ± 1.6 MPa at room temperature. The high ductility from the combined effects of the grain refinement, dispersion of nanoscale I-phase particles, and the unusual texture. The uniform dispersion of nanoscale I-phase particles could promote grain refinement by particle stimulated nucleation mechanism, and thus bring the unusual texture (where the c-axis is aligned parallel to the extrusion direction during dynamic recrystallization, which contributed to ductility).