Al-Li Alloys – The Analysis of Material Behaviour during Industrial Hot Forging

Al-Li alloys are a promising class of aerospace materials that combine light weight with high strength, comparable to those of steels. In the case of critical components, it is well known that providing the required reliability is impossible without tailoring the output microstructure of the material. This, in turn, requires a clear understanding of the logic behind microstructure formation depending on the total processing history (especially temperature and strain-rate history). However, uniaxial isothermal laboratory tests provide very limited information about the material behaviour. Real forging processes, especially involving complex geometries, sometimes develop quite complicated temperature-strain-rate paths that vary across the deformed part. A proper analysis of the microstructural transformations taking place in the material under these conditions is therefore very important. In this paper, the correlation between the loading history and microstructural transformations was analysed for AA2099 alloy using the hot forging of a disk-shaped component at selected forging temperatures and strain rates. The obtained results were compared to industrial processing maps based on uniaxial tests

Optimization of hot press forging parameters in direct recycling of aluminium chip (AA 6061)

This study introduces a new approach of direct recycling using the hot press forging process that eliminates the two intermediate processes of cold-compact and pre-heating. This method leads to low energy consumption without intervening the metallurgical processes. In this study, the optimum of machined chips from high speed milling is recycled by hot press forging. The mechanical properties and surface integrity of the different chips were investigated. The performance of recycled aluminium AA 6061 chips in the mechanical and physical properties were compared with the original aluminium billet. Response surface methodology (RSM) was used to develop mathematical model of the effects on pre-compaction cycle, holding time and suitable pressure significant to the process. It is hoped that, utilization of primary metal could be fully utilized by direct recycling technique (hot press forging) introduced in this study and at the same time developing a sustainable manufacturing process technology for future needs

Sinter forging of zirconia toughened alumina

Sinter forging experiments have been carried out on powder compacts of zirconia toughened alumina (ZTA) Ceramics Alumina-15 wt% zirconia was prepared by a gel precipitation method and calcined at temperatures of 900 or 1100°C. Full densification of ZTA ceramics was obtained within 15 min at 1400°C and 40 MPa. A homogeneous microstructure can be observed with an alumina grain size of 0.7 mgrm and a zirconia grain size of 0.2 mgrm. Almost no textural evolution occurred in the microstructure. During sinter forging the densification behaviour of the compacts was improved by an effective shear strain, for which values of more than 100% could be obtained. As a result of the shear deformation the densification of ZTA in the agr alumina phase stage shifted to lower temperature. During pressureless sintering the gamma to agr alumina transformation temperature was dependent of the preceding calcination temperature, while during sinter forging this phase transformation was independent of calcination temperature and took place at a lower temperature

Forging Unique Nursing Careers

Three nursing alumni have melded their careers with other interests in unlikely locations — the legal arena and ships

Modelling of forging processes assisted by piezoelectric actuators : principles and experimental validation

This paper presents the modelling of a forging processes assisted by a piezoelectric actuator (PA), which is used to generate specific low frequency vibration waveforms. Experimental results show that such waveforms reduce the necessary forging force during upsetting tests. The main problems which remain are defining the appropriate waveforms, predicting their influence on the process and the actuator and designing the control. Due to the complexity of the interactions between the different components of the system, a complete model of the process is needed. Such a model is developed here using an energetic macroscopic representation to preserve causality throughout the modelling. Simulation results are then compared to representative experimental results

Effect of operating temperature on direct recycling aluminium chips (AA6061) in hot press forging process

A method of solid-state recycling aluminum alloy using hot press forging process was studied as well as the possibility of the recycled chip to be used as secondary resources. This paper presents the results of recycled AA6061 aluminium alloy chip using different operating temperature for hot press forging process. Mechanical properties and microstructure of the recycled specimens and as-received (reference) specimen were investigated. The recycled specimens exhibit a good potential in the strength properties. The result for yield strength (YS) and ultimate tensile strength (UTS) at the minimum temperature 430˚C is 25.8 MPa and 27.13 MPa. For the maximum operating temperature 520˚C YS and UTS are 107.0MPa and 117.53 MPa. Analysis for different operating temperatures shows that the higher temperatures giving better result on mechanical properties and finer microstructure. The strength of recycled specimen increases due to the grain refinement strengthening whereas particle dispersion strengthening has minor effects. In this study, the recycled AA6061 chip shows the good potential in strengthening as the comparison of using only 17.5% of suggested pressure (70.0/400.0) MPa, the UTS exhibit 35.8% (117.58/327.69) MPa. This shows a remarkable potential of direct recycling by using hot press forging process

Deformation processes in forging ceramics Progress report, 19 Dec. 1969 - 19 Mar. 1970

Deformation processes in forging ceramic

Influence of the constitutive flow law in FEM simulation of the Radial forging process

Radial forging is a widely used forming process for manufacturing hollow products in transport industry. As the deformation of the workpiece, during the process, is a consequence of a large number of high-speed strokes, the Johnson-Cook constitutive law (taking into account the strain rate) seems to be well adapted for representing the material behavior even if the process is performed under cold conditions. But numerous contributions concerning radial forging analysis, in the literature, are based on a simple elastic-plastic formulation. As far as we know, this assumption has yet not been validated for the radial forging process. Because of the importance of the flow law in the effectiveness of the model, our purpose in this paper is to analyze the influence of the use of an elastic-viscoplastic formulation instead of an elastic-plastic one for modeling the cold radial forging process. In this paper we have selected two different laws for the simulations: the Johnson-Cook and the Ludwik ones, and we have compared the results in terms of forging force, product’s thickness, strains, stresses, and CPU time. For the presented study we use an AISI 4140 steel, and we denote a fairly good agreement between the results obtained using both laws