Development of an Aluminum-Based Hybrid Billet Material for the Process-Integrated Foaming of Hollow Co-Extrusions

Metal foams are attractive for lightweight construction in the automotive sector since they provide high-energy absorption and good damping properties, which is crucial, e.g., for crash structures. Currently, however, foams are produced separately and then pasted into the components. Consequently, the overall mechanical properties depend significantly on the quality of the adhesive bond between the foam and the structural component. A new process route for the manufacture of hybrid foamed hollow aluminum profiles is proposed. In this approach, a foamable precursor material is directly integrated into the extrusion process of the hollow structural profile. To this end, special low-melting alloys were developed in this study to enable foaming inside the aluminum profile. The melting intervals of these alloys were examined using differential scanning calorimetry. One of the promising AlZnSi alloys was atomized, mixed with a foaming agent and then compacted into semi-finished products for subsequent co-extrusion. The foaming behavior, which was investigated by means of X-ray microscopy, is shown to depend primarily on the mass fraction of the foaming agent as well as the heat treatment parameters. The results demonstrate that both the melting interval and the foaming behavior of AlZn22Si6 make this particular alloy a suitable candidate for the desired process chain.

Subsequent drawing of anisotropic viscous-plastic material

The proportions for stress computation at the subsequent drawing of anisotropic billet under conditions of viscoplasticity are obtained. The equilibrium equations in stresses and a linear condition of fluidity are used. The impact of billet bending upon radial areas of a matrix and clamping and also friction is taken into account. The assessment of billet material damageability is carried out.

Variation assessment of yield mode at pressure welding

There are offered ratios for the computation of deformation and power modes of yielding at billet pressure welding. A power method is used for the computation of pressure with reference to a flat discontinuous field of movement speeds. Pressure minimization is carried out in a variation way. The assessment of billet material damageability is shown.

Analysis of a new process of forging a 2017A aluminium alloy connecting rod

The paper presents the results of a theoretical analysis of a new process of hammer forging of a connecting rod and the technology currently used. In the industry at present connecting rods are forged from extruded rods. The new forging technology assumes the use of a billet in the form of a cast preform. For the calculations, it has been assumed that the billet material will be a Ø30 x 148 mm rod and a cast preform. Two variants of preforms have been modelled, from which products of the assumed geometry with different degree of strain are obtained. Calculations were made using the finite element method in the Deform 3D program. The input material was 2017A aluminium alloy in the form of rods and sand cast preforms. On the basis of the conducted research it was found that the use of cast preforms reduces material waste by about 80% in relation to the technology of forging from the bar, and reduces the energy consumption of the process by about 75%. Both geometrical variants of the forging preforms ensure obtaining a forging with the assumed shape and dimensions, although forging from the forging preform with a smaller degree of strain seems to be a safer variant in terms of the possibility of cracking of the material. This is supported by the lower strain and Cockcroft-Latham integral values.

Developing a novel manufacturing method to produce stiffened plate structures

Isogrid is a highly efficient stiffened plate structure which was developed in the aerospace industry for use in rocketry and space structures. Its current form is unviable outwith these applications, as the available production methods are expensive due to excessive machining time in addition to considerable material wastage. The method detailed in this body of work was developed to manufacture Isogrid in a more efficient manner, so that its weight-saving properties may become more widely accessible. This novel Isogrid manufacturing process uses a rolling mill with patterned rollers to imprint a 3D structure of ribs into the surface of a billet material. To validate this method, a patterned roller was designed, manufactured and fitted to a rolling mill to produce sheets of aluminium AA1050 Isogrid. This process successfully created Isogrid in a sustainable, rapid manner. The samples produced were tested in 3-point bending and compared against flat plate of the same material. They were found to be 100% stronger in bending compared to a neutral flat plate with a strength shape factor of 1.6 after discounting the effect of cold work.

Improvement of numerical methods of contact stress calculation during cold rolling of band

The influence of a contact surface shape of the deformation zone during cold rolling of a band on the rolling force subject to parameters of the strain strengthening curve of billet material and band tension has been studied by numerical methods. The comparison of the obtained results and well-known ones allowed one to set that in case of the presense of strain strengthening, the replacement of the arc of contact by the chord resulted in a decrease in calculated force of rolling, whose value depends on the presence of the fore tension and the back tension and parameters of strain strengthening of metal.

The fracture behavior transitions in cold dwell fatigue of Ti-6Al-4V

Ti-6Al-4V forged materials which had fine grain size and commercial billet which had moderate grain size and micro texture were prepared. Cold dwell fatigue tests were conducted using both materials, and dwell time condition was up to 1800s. Fracture cycles and elongation were almost same on each specimen. Number of cycle to failure decreased with increase of dwell time. Fracture elongation increased up to dwell time of 10s, and it was constant in over 10s. Fracture surface were observed. In short time dwell condition up to 2s, fracture surface showed fatigue type. Fracture surfaces changed to dimple in over 10s dwell. In billet material, facets were observed in inner area of fracture surface.

Miniature Hemispherical Bowl-Shaped Forming Using SLA Punch and Die: Modeling and Experimental Analysis

Forming processes are a convenient means for bulk production of parts. These parts are used in a wide range of applications from automotive industries to micro-devices in bioengineering. Manufactured parts are required to be precise in their final dimension, and since the billet material undergoes significant plastic deformation during forming, billet material characterization and prediction of final form is essential. In this study, miniaturized bowl-shaped samples of 3003-H14 aluminum alloy were formed using a die and punch manufactured using the stereolithography (SLA) additive manufacturing method. Tensile testing was performed in order to characterize the material properties of the SLA resin. Using the SLA-created die and punch, hemispherical bowl-shaped forms were generated. In order to investigate possible small size effects, experimental load versus displacement results were obtained for billet plate thicknesses of 0.4–0.8 mm. A numerical finite element model was developed to predict the required punch load to manufacture various thickness bowl-shaped forms. A comparison was made between the load verses displacement curves for the different thicknesses, and the numerical model was validated by the experimental results. The validated computational model can then be used to predict the process parameters prior to starting bulk production. Finally, a model with grains was developed and simulated to show the virtual microstructural morphology of the circular plates before and after the forming operation.