Effect of Strain Path on Microstructure and Texture Development in ECAP Processed AA3104 Alloy

Abstract

The objective of the study was to determine the effect of strain path on texture, microstructure and mechanical properties development of severely deformed Al-Mn-Mg alloy. The commercial purity material (AA3104 alloy) was deformed via Equal Channel Angular Pressing (ECAP) up to 10 passes following routes A, B, and C. The deformed and partially recrystallized microstructures and the crystallographic textures were characterized by transmission (TEM) and scanning (SEM) electron microscopy including systematic local orientation measurements (TEM and SEM FEG orientation mapping). The crystallographic texture was determined using X-ray diffraction on a sample section perpendicular to the extension direction (ED). In order to estimate the homogeneity of strengthening the systematic measurements of Vickers micro hardness in the plane perpendicular to the ED was performed. It was found out that different routes led to strong differences in microstructure of billets. In the case of route A and B strong macro cracking appeared after 5 and 3 passes, respectively. A good quality billet after 10 passes was obtained only in the case of route C. Texture evolution turned out to follow nearly the same ‘course’ for different routes of ECAP. However, the intensity of particular texture components was different in each case. TEM observations and local orientation measurements allowed identifying fine and strongly disoriented planar dislocation structure of nanolayers in the case of route A and C. In the case of route B nearly equiaxed structure of fine grains was observed after 3 passes. Moreover, irrespective of the applied deformation routes large, not deformable second phase particles strongly influenced strengthening of the matrix and nucleation during the recrystallization.