Equal channel angular pressing is one of the most popular processes for the fabrication of ultrafine-grained (UFG) materials. Homogeneous strain distribution is one of the main expected outputs in this process. Recently, a new modification has been applied on the ECAP die in which the workpiece undergoes twisting in the exit channel which is defined as the helix angle of the die. In this paper, the effect of the helix angle in the exit channel along with other effective parameters, including friction coefficient and die channel angle was investigated by the FEM method. At first, a FEM model was developed based on available experimental data. Having verified the FEM model, Taguchi's design of the experimental approach was employed in which the helix angle and friction coefficient had four levels and the die channel angle had two levels. Evaluating the obtained results by the ANOVA method showed that the p-value of the helix angle was 0.01 i.e., the helix angle was an effective parameter on strain distribution and maximum imposed strain. The results also showed that the homogeneity of strain distribution decreases with increasing the friction coefficient and the helix angle and increases with increasing the die channel angle. Also, increasing the helix angle led to an increase in the maximum imposed strain. Manuscript profile

In recent years, processes known as severe plastic deformation (SPD) have been devised to create fine-grained materials. Among these processes, equal channel angular pressing (ECAP) has been more favored than other methods due to its high efficiency, simplicity, and industrial production potential. This study aimed to investigate the sample temperature gradient during the ECAP process. For this purpose, a Taguchi experiment with influencing factors on AA2017 alloy was designed and a relationship was obtained to predict sample surface temperature. Experiments were carried out using grease, graphite powder, and MoS2 lubricants, along with routes A, BC, BA, and C. The surface temperature of the sample was measured using a laser thermometer. A finite element model was compared with the experimental conditions, and the simulation and experimental results of surface temperature were verified with an error of about 1.9%. In experiments, it was found that speed and lubricant had a significant effect on sample temperature during the process. The simulation results showed that decreasing the die angle resulted in a significant increase in temperature. Following the validation of the FEM model, the temperature gradient and distribution in the middle of the sample, wherein practical experiments could not be measured, were also investigated. Manuscript profile

Blanking is a sheet metal cutting process,which itself is a prerequisite for many other forming processes. Punch and matrix shape and material, punch force and speed, lubricant, corner radius, and punch-matrix clearance are important variables in blanking. Clearance is critical in this process, depending on the material and sheet thickness, and is usually a percentage of the sheet thickness. Too much clearance causes the sheet to press and pull into the clearance area and Low clearance causes misaligned fracture lines and secondary cutting. Producing blanking with high thicknesses is always one of the challenges of the sheet metal blanking process. This study aims to create 57.5 mm diameter StW24 steel blanks with 12 mm thickness and a 38% penetration value. A blanking die was designed and built with different punches based on clearance values of 9, 15, and 21% to match the target drawing. Results show that increasing clearance from 9 to 15% leads to an 11% thicker rollover zone, 5% thicker fracture zone, and 33% thinner shear zone. Increasing clearance from 15 to 21% reduces the thickness of rollover, fracture, and shear zones by 24, 3, and 56% respectively. Increasing clearance from 9 to 21% also leads to a 51% increase in fracture angle and a 34% increase in burr size. Clearance of 15% of sheet thickness is best for producing blank as per the target drawing. Manuscript profile