Papers by Keyword: Hot Extrusion

Abstract: Aluminum 7000 series alloys are widely used for aerospace and transportation applications due to their high strength-to-weight ratio. This research investigates the impact of zinc (Zn) and magnesium (Mg) content on the hot extrudability and tribological behavior. Elemental quantities straight away impact flow stress, determining the manufacturing parameters, whereas galling and adhesion frequently degrade tool life. This work illustrates that by assessing essential ram speeds and temperature limits, adjusting Zn and Mg concentrations considerably improves the extrudability limit. A decreasing flow stress during deformation reduces micro-cracking tendency and improves surface quality. The findings provide critical compositional guidelines for high-strength aluminum alloys, effectively balancing processing efficiency with improved surface quality and reduced element adhesion behavior, ensuring better industrial outcomes for advanced structural components.

Abstract: Aluminum alloys in the 7000 series are high-strength alloys that are used in a wide variety of products in the transportation equipment and aerospace fields to reduce weight. In particular, the A7075 alloy has the highest strength and is expected to find further applications in a wide range of fields such as aircraft parts and sporting goods. However, low productivity is a problem due to its high deformation resistance, tendency to produce surface defects called tearing on the product surface, and short tool life. Tearing tends to occur under high temperature and high speed conditions, and is thought to be caused by local melting of Zn, an additive element, due to heat generation in processing. In this study, to improve the productivity of A7075 alloy, the profile was cooled during extrusion to prevent recrystallization of extrudate surface grains due to processing heat and to prevent processing heat during forming. In order to investigate the cooling effect, hot extrusion simulation was conducted. The cooling effect successfully suppressed the occurrence of tearing. These results indicate that cooling the extrudate during forming reduces the effect of heat generation during forming and prevents recrystallization of the extrudate surface grains and local melting of Zn.

Abstract: 7000 series aluminum alloy is a high-strength alloy and used in a wide variety of products for the purpose of weight reduction in the field of transportation equipment and aerospace. In particularly, A7075 alloy has the highest strength and is expected to be further applied in a wide range of fields such as aircraft parts and sports equipment. However, it has high deformation resistance and is prone to surface defects called tearing. Tearing affects the productivity because it requires to lower the speed. Tearing is likely to occur under high temperature and high speed conditions. It is thought that the localization of melting of Zn-compounds and additive compounds occur due to heat generated during process leading to tearing. In this study, in order to increase the productivity without tearing, die surface quality was considered to prevent the effect of friction and generated heat at interface between tools and material. In addition, recrystallization was also eliminated by reducing friction because temperature does not increase up to the range of recrystallization temperatures. The AlCrN coating was used to improve die surface quality comparing to Nitriding. It was found that the tearing size and heat generated by using AlCrN coating were small. In addition, grain size was small and observed at the tearing region on the extruded surface. It is thought that the die coating can reduce the effect of friction at interface and prevent the recrystallization of the extruded surface. Furthermore, the localization of melting of Zn-compounds and additive compounds are also decreased. From above results, tearing sensitivity can be decreased by using coating to increase productivity speed of A7075 alloy.

Abstract: Macro-, microstructural, fine structure, phase composition, texture and complex of physical and mechanical properties in titanium alloy VT23 (Ti-5.5Al-4.7V-2.5Mo-1.1Cr-0.7Fe, wt. %) tube were studded by the macroanalysis, optical and transmission microscopy, X-ray phase analysis, durometry and microindentation methods. A close relationship between the structural-textural-phase state formed during the extrusion and the obtained level of strength, plastic, durometric properties and the contact modulus of elasticity in a hot-extruded tube has been established.

Abstract: The effect of extrusion ratios and solution heat treatment on microstructure and tensile properties of extruded Al-15%Mg₂Si-1.0%Gd composite was investigated. The as-cast composite was hot extruded using three different dies and solution heat treated. After conducting heat treatment on extruded samples, microstructure alteration was examined using scanning electron microscope (SEM). Furthermore, mechanical properties of the composites were studied with tensile test. The results demonstrated that extruded and heat treated composite possesses higher strength and ductility compared to as-extruded composites. It was also found that the extrusion and heat treatment processes altered the morphology of primary Mg₂Si particles as well as reduction in their size especially when the extrusion ratio increases. Fracture surface examination revealed a transition from ductile fracture in as-extruded samples to more ductile fracture in extruded and heat treated ones. This can be attributed to the change in size and morphology of primary Mg₂Si particles as well as fragmentation of Gd intermetallic compounds.

Abstract: The study considers the formation of the structure, texture, and hardness of hot extruded tube of titanium alloy PT-1M. It is shown that hot extrusion at 840 °C, which is higher than the α-phase recrystallization temperature, results to the development of dynamic and primary recrystallization processes and ensures the formation of homogeneous and fine-grained structure through-out the cross section with a two-component tangential texture (0001)TD<100>ED+(0001)TD<110>ED (TD – tangential direction, ED – extrusion direction) and hardness of 155 HV. It has been established that a higher cooling rate of the surface areas of the tube after extrusion results to a less active development of recrystallization processes, which lead to the formation of a finer granular structure near the outer surface. This weakens recrystallization component of (0001)TD<110>ED, compared to other areas of the tube.

Abstract: Produced Profiles by direct recycling of aluminum chips in hot extrusion process were achieved by temperature related parameters using preheating temperature 450 °C, 500 °C, and 550 °C for duration 1 hour, 2 hours, and 3 hours preheating time. By using Design of Experiments (DOE) procedure with full factorial design and three center points analysis, the results showed that the preheating temperature factor is more important to be controlled rather than the preheating duration and increase of temperature conducted to the high tensile strength. The profiles extruded at 550 °C and 3 hours’ duration had obtained the optimum condition to get the maximum tensile strength. The influence of parameters of hot extrusion process on fracture surfaces of the recycled samples was also investigated and discussed.

Abstract: This research investigated the effect of hot extrusion on the flow behaviour of nickel-based superalloy FGH4096 by hot compression experiments in the temperature range from 1020 to 1110 °C and strain rates ranging from 0.1 to 0.001 s^-1. The influence of the hot extrusion on the initial microstructures, work hardening rate, strain rate sensitivity, and activation energy of deformation were discussed. The results show that the extruded microstructure is constituted by the fine dynamic recrystallisation of grains. The true strain-true stress curves show that the as-HIPed and as-HEXed FGH4096 superalloy present double flow stress peaks and discontinuous flow softening. The as-HEXed FGH4096 is easily dynamically softened at high temperatures and high strain rates compared with as-HIPed microstructures. As for the work hardening rate, the as-HEXed FGH4096 exhibits higher θ values than that of as-HIPed. It is beneficial to the homogenous deformation and grain refinement during subsequent turbine disk forging. Comparing to as-HIPed FGH4096, the highest strain rate sensitivity value of as-HEXed is 0.306 at 1110 °C. The isothermal superplastic forging of a P/M turbine disk may be carried out at this temperature. The deformation activation energy value of the as-HIPed FGH4096 is lower which means that dislocation sliding and climbing can be easily initiated in the as-HIPed alloy.

Abstract: In this work, p-type thermoelectric material was produced by hot extrusion of pre-synthesized in injection molding machine Bi_0.5Sb_1.5Te₃ solid solution. During the research radial distribution of the Seebeck coefficient was confirmed and described in material’s cross section using thermal measuring probe. Such nonuniformity of the Seebeck coefficient is correlated with the strain-stress state of extrudate specifically with the distribution of accumulated strain intensity, which was obtained by mathematical modeling of extrusion process using the software package DEFORM.

Abstract: This article describes the practical application of hot extrusion for compaction of magnesium shavings in semi-finished products and the study of the influence of process parameters on the mechanical properties of the obtained MA5 (AZ80) magnesium alloy bars. Production of bars was carried out at different heating temperatures and plastic deformation degree to find technology provide the best combination of tensile and compressive properties. The resulting bars are somewhat higher in strength characteristics than the strength of deformed cast bars made from MA5 alloy, however, they are significantly lower in ductility.