Finite Element Analysis of ECAP, TCAP, RUE and CGP Processes

A finite element method was applied to study the various severe plastic deformation processes like, Equal Channel Angular Pressing (ECAP), Tubular Channel Angular Pressing (TCAP), Repetitive Upsetting and Extrusion (RUE) and Constrained Groove Pressing (CGP), considering aluminum AA-390 alloy as specimen material for all these processes. FEA simulation was carried out using AFDEX simulation tool. Effect of the various ECAP process parameters like, die corner angle, channel angle, and the coefficient of friction were analyzed. The die corner angles were divided into 2 equal parts for increasing the effectiveness of ECAP process, thereby increasing the channel number from 2 to 3 and further, their influence on ECAP process was investigated. A 3D simulation of TCAP was carried out for die shapes like triangular and trapezoidal, and variation of the generated stress and strain was plotted. In CGP, four cycle operation was carried out; wherein each cycle is composed of corrugating the specimen and subsequent straightening to original dimension. During RUE process, a maximum effective stress of 683.1 MPa was induced in the specimen after processing it for four complete cycles of RUE process; whereas the maximum strain induced during the same condition was 3.715

A comparison of repetitive corrugation and straightening and high-pressure torsion using an Al-Mg-Sc alloy

A comparative study was conducted to evaluate the influence of two different severe plastic deformation (SPD) processes: repetitive corrugation and straightening (RCS) and high-pressure torsion (HPT). Samples of an Al-3Mg-0.25Sc alloy with an initial grain size of ∼150 μm were processed by RCS through 8 passes at room temperature either without any rotation during processing or with a rotation of 90° around the longitudinal axis between each pass. Thin discs of the alloy were also processed for up to 5 turns by HPT at room temperature. The results show that both procedures introduce significant grain refinement with average grain sizes of ∼0.6–0.7 μm after RCS and ∼95 nm after HPT. Measurements of the Vickers microhardness gave values of ∼128 after RCS and ∼156 after HPT. The results demonstrate that processing by HPT is the optimum processing technique in achieving both high strength and microstructural homogeneity

Influence of RCS on Al-3Mg and Al-3Mg-0.25Sc alloys

An influence of repetitive corrugation and straightening (RCS) was studied on Al-3Mg and Al-3Mg-0.25Sc alloys up to eight passes. Each pass consist of a corrugation and followed by straightening. This has resulted in introducing large plastic strain in sample, and thus led to formation of sub-micron grain sizes with high angle grain boundaries. These sub grain formation was eventually resulted in improved mechanical properties. The average grain size of Al-3Mg-0.25Sc alloy after 8 passes yielded to ~0.6pm. Microhardness, strength properties were evaluated and it suggests that RCS was responsible for high hardness values as compared to the as cast samples. The microhardness values after RCS were 105 HV and 130 HV for Al-3Mg and Al-3Mg-0.25Sc alloys, respectively. Similarly, ~ 40% improvement in tensile strength from 240 MPa to 370 MPa was observed for Al- 3Mg-0.25Sc alloy after RCS process.Al-3Mg and Al-3Mg-0.25Scalloys exhibited maximum strength of 220 MPa and 370 MPa, respectively. It is concluded that RCS process has a strong influence on Al- 3Mg and Al-3Mg-0.25Sc alloys for obtaining improved mechanical properties and grain refinement. In addition to RCS process and presence of AESc precipitates in Al-3Mg-0.25Sc alloy had a significant role in grain refinement and improved mechanical properties as compared to Al-3Mg alloy