An analysis of the extrusion of bimetallic tubes by numerical simulation (original) (raw)
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Using finite element and polycrystalline plasticity modeling, we explore the influence of die design and material behavior on the extrusion of bimetallic tubes. Three distinctly different extrusion designs are introduced and evaluated based on a range of macroscopic and microstructural criteria: die and punch stress, interface roughness, peak forming loads, and strain and crystallographic texture heterogeneities across the tube thickness. We find that an extrusion die design proposed here that differs from the conventional one is better for reduction of peak forming load satisfying objectives of the traditional design. However, when the design is more constrained and considerations of strain and microstructural heterogeneities and gradients are made part of the design criteria, we show that one die design promotes such gradients while the other minimizes them. In all three designs, large disparities in flow stress and hardening rate (>3 times) lead to larger interfacial strain gradients. These findings provide basic die designs that can be used to evaluate the degree and locations of strain and texture gradients across the tube thickness.
Fracture Phenomenon in Simulation of Bimetallic Rods Extrusion Process
Acta Metallurgica Slovaca, 2013
Mechanical behaviour of metallic material is different during its deformation as monometallic one in comparison with deformation as a component of composite. The different flow characteristics of two materials enhance the inhomogeneity of the extrusion process. This lead to poor tolerance throughout the extrudate fracture of the core or fracture of the sleeve. The concept of FEM Marc Mode has been presented with results which may indicate the possibility of assessment of existing fracture criteria for composite material. The present study shows that prediction based on the criterion including σ max , , , ε f is reflected in experimental results. Fracture phenomena dependency occurring on geometrical arrangement of billet has been presented. The values of R i /R 0 ratios were lower the probability of fracture occurrence was higher.
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The hydrostatic extrusion is a new method of extrus ion process. The most important advantage of this method is reduction of friction and close tole rance for the coating thickness. In this study, the hydrostatic extrusion simulation of bimetallic wire s has performed using of finite element method. In the following the advantages of hydrostatic extr usion compared to the direct extrusion are presented.It can be concluded that by increasing th e friction coefficient between the work piece and the die, the extrusion force value also increases. Increasing the cross-section reduction when the die angle kept constant as a result of increase in die length, consequently leads to an increase in the extrusion force.Regarding to the absence of frictio n in the die and almost uniformly deformation and homogeneous in the hydrostatic extrusion, the p roduct with a uniform coating thickness can be obtained as it is very important for manufacture of very high length bi-metal products.
Materials, 2021
This paper investigates the effect that the selection of the die material generates on the extrusion process of bimetallic cylindrical billets combining a magnesium alloy core (AZ31B) and a titanium alloy sleeve (Ti6Al4V) of interest in aeronautical applications. A robust finite element model is developed to analyze the variation in the extrusion force, damage distribution, and wear using different die materials. The results show that die material is a key factor to be taken into account in multi-material extrusion processes. The die material selection can cause variations in the extrusion force from 8% up to 15%, changing the effect of the extrusion parameters, for example, optimum die semi-angle. Damage distribution in the extrudate is also affected by die material, mainly in the core. Lastly, die wear is the most affected parameter due to the different hardness of the materials, as well as due to the variations in the normal pressure and sliding velocity, finding critical values ...
Bi-Metallic Cold Backward Extrusion - Numerical Simulation with Experimental Verification
2012
Bi-metallic extrusion is a metal forming operation where billet is composed of two different metallic materials which are then concurrently extruded into a final workpiece. In this way final component, consisting of two different materials which are metallurgically bonded, is created. Extrusion of bi-metallic workpieces differs in many aspects from the classical single-metal extrusion. Although bi-metallic extrusion enables beneficial utilization of favourable characteristics of both paired materials, this process has not been often applied in the industrial practice so far. This is mainly due to the certain dearth of knowledge and experience in this field. The present study is bound to the backward extrusion of bi-metallic materials. Combination of Al-Cu as a billet composition is explored numerically and experimentally. Material flow as well as mechanical properties of the obtained bi-metallic component have been determined and analysed.
International Journal of Mechanical Sciences, 2001
The generalised upper bound technique previously applied to the determination of working pressures in extrusion-piercing of solid billets (Chitkara NR, Aleem A. Int J Mech Sci 2001;43:1685-709.) to form hollow monometallic tubes is extended to analyse the problem of bi-metallic tube extrusions through proÿle shaped dies and mandrel combinations. Theoretical results of mean extrusion pressures obtained from the generalised upper bound analysis are compared with those obtained earlier by the generalised slab method of analysis (Chitkara NR, Aleem A. Int J Mech Sci 2001;43:2857-82.) and some experiments. A few salient observations made during the experimental investigations carried out into forward extrusion of bi-metallic tubes made of h.c. copper and c.p. aluminium are also given and the results commented upon.
Finite element analysis of multi-hole extrusion of aluminum-alloy tubes
Journal of Materials Processing Technology, 2008
The multi-hole extrusion of aluminum-alloy tubes was examined in the present study using both the finite element analysis and the experimental approach. The finite element analysis was first validated qualitatively and quantitatively by the experimental data obtained from the single-hole extrusion process. The effects of the process parameters, such as extrusion temperature, extrusion speed, dimensions of billet, and location of holes on the extrusion load and the shape of extruded tubes were then studied by the finite element analysis. The finite element analysis reveals that the most crucial process parameter is the number of holes and their locations on the extrusion die. It is also found that a uniform deformation of mandrel and a balanced flow at the exit of extrusion die could be achieved if the position of holes is near the centroid of the die area. An expression of the eccentricity of the holes was defined by a ratio. An eccentricity ratio that represents an optimum position of the holes was then developed for the two-hole extrusion of aluminum-alloy tubes to avoid any bending or curvature of the extruded product. The developed approach could be also extended to other multi-hole extrusion of more than two tubes and help the die engineer to design a more productive extrusion process.