H. Shokrvash, A. Vajd, M. Shaban Ghazani,
Volume 34, Issue 4 (3-2016)
Abstract
In the present research, an effective thermo-mechanical processing route in the temperature range of metastable austenite region (Ae3<T< Ar3) was employed to achieve ultra-fine grain size in a plain low carbon steel during integrated extrusion equal channel angular pressing. At first, the effect of preheating temperature on the strain and temperature distributions inside the deformed samples were investigated using 3D finite element simulation. According to the result of FEM simulation, the preheating temperature of 930 ˚C was selected as an appropriate temperature for fabrication of ultra-fine ferrite structure. Severe plastic deformation was then imposed on samples with the predicted preheating temperature and the results showed a great consistency with FEM simulation predictions. Optical micrographs taken from the center point of the samples showed that the ferrite grains could be refined from 32 μm to 1-3 μm by different mechanisms.
S. E. Mousavi, M. Meratian, A. Rezaeian,
Volume 36, Issue 4 (3-2018)
Abstract
Equal Channel Angular Pressing (ECAP) is currently one of the most popular methods for fabricating Ultra-Fine Grained (UFG) materials. In this study, mechanical properties of the 60-40 two phase brass processed were evaluated by ECAP. The samples were repeatedly ECAP-ed to strains as high as 2 at a temperature of 350 ◦C using route C. The microstructure of the samples showed that small grains were formed in the boundaries which indicates the occurrence of recrystallization in different passes. Observation of slip trace in the microstructure of the samples showed that even in such alloy with a low-stacking fault energy, dislocations slip trigger the deformation. Investigation of mechanical properties showed that with increasing the number of passes, tensile strength, microhardness and ducility improved at the same time.
