FEM analysis to predict development of structure during extrusion and subsequent solution soak cycle

Abstract

Materials which form the surface and subcutaneous layers of an extrudate experience large deformations when they traverse the die land, which, added to the inhomogeneous caused by the dead metal zone, leads to considerable modifications to the deformation parameters when compared with the remainder of the extrusion. The distribution of structure is therefore greatly inhomogeneous. Reference to both empirical and physical models of the recrystallisation process indicates that nucleation and growth will differ at these locations in those alloys that are usually solution treated and aged subsequent to the deformation process. Since static recrystallisation (SRX) has a significant influence on many of the properties of the extrudate, it is therefore essential to provide the methodology to predict these variations. In the present work, a physical model based on dislocation density, subgrain size and misorientation is modified and integrated into the commercial FEM codes, FORGE2 and FORGE3 to study the changes of the microstructure. Axisymmetrical and shape extrusion are presented as examples. The evolution of the substructure influencing SRX is studied. The metallurgical behaviours of axisymmetric extrusion and that of shape extrusion are compared. The predicted results show an agreement with the experimental measurement. The distribution of equivalent strain, temperature compensated strain rate and temperatures is also presented to aid in interpretation. Importantly the properties of hard alloys improve with the increase in the temperature of the extrusion. This phenomenon is discussed and theoretically justified.

On material flow and aspects of structural modification during direct and indirect extrusion of aluminium alloy

“…Flitta and Sheppard 10,11 have used Forge to predict the required extrusion load, extrudate temperature and metal flow. Using Forge2, Duan and Sheppard 12 and Flitta et al 13 also successfully predicted extrusion load, temperature, pressure, the evolution of the volume fraction recrystallised (X V ), subgrain size and internal dislocation density of the extrudate.…”

Experimental and numerical prediction of extrusion load at different lubricating conditions of aluminium 6063 alloy in backward cup extrusion

“…deformation load). The structure evolution and the strain hardening of the extrudate are because of the amount of deformation load generated from the extrusion parameters and die shape (Flitta et al, 2007;Libura & Zasadziński, 1992;Solomon & Solomon, 2010). Therefore, in recent times, many extrusion parameters have been investigated to minimize the forces involved during metal deformation and flow process (Jolgaf et al, 2008;Oyinbo et al, 2015).…”

Effect of frictional boundary conditions and percentage area reduction on the extrusion pressure of Aluminum AA6063 alloy using FE analysis modelling

“…This process offers several advantages in contrast to the requirements of other manufacturing processes in terms of reduction in material wastage (scraps) as well as improved the products' mechanical properties. The extrusion process in massive metal deformation plays a vital role by reducing the billets' cross-sectional area when forced through a die by a ram (Flitta et al, 2007;Solomon & Solomon, 2010;Altinbalik & Ayer, 2013). Materials such as metals, polymers, foodstuffs, ceramics and concretes are commonly extruded.…”