Upper bound solution of equal channel forward extrusion process as a new severe plastic deformation method

In this paper, rigid block upper bound method has been utilized to analyze the equal channel forward extrusion process as a novel severe plastic deformation technique. This process transforms a billet with rectangular cross-section of a x b into b x a by extrusion which makes it, equal channel. After verifying the process using numerical and experimental works, the influence of process parameters on forming force has been investigated. The results indicate that there exists an optimum main deformation zone height from which the forming load is a minimum for any given friction coefficient and length to width ratio. Additionally, increasing the friction coefficient at the constant length to width ratio or decreasing the length to width ratio at the constant friction coefficient leads to the reduction of the optimum main deformation zone height. Furthermore, the effect of the length to width ratio is more significant than the friction coefficient on both the optimum main deformation zone height and anticipated extrusion load. Finally, higher values of length to width ratio and friction coefficient result in a higher extrusion force.