Evaluation of microstructure anisotropy on room and medium temperature ECAP deformed F138 steel

Abstract

The microstructure developed during severe plastic deformation results in improved mechanical properties because of the decrease in domain sizes and accumulation of defects, mainly dislocation arrays. The characteristic deformation stages observed in low stacking fault energy (SFE) face centered cubic (FCC) materials are highly influenced by the development of the primary and secondary twinning that compete with dislocation glide. In this paper, a low SFE F138 stainless steel is deformed by equal channel angular pressing (ECAP) up to 4 passes at room temperature (RT) and at 300°C to compare the grain refinement and twin boundary development with increasing deformation. Tensile tests were performed to determine the deformation stages reached by the material before and after ECAP deformation, and the resulting microstructure was observed by TEM. X-ray diffraction and EBSD, average technique the first and local the second one, were used to quantify the microstructural changes, allowing the determination of diffraction domain sizes, dislocation and stacking fault densities and misorientation indices, which lead to a complete analysis of the deformation introduced in the material, with comparative correlations between various microstructural parameters.

Texture and Differential Stress Development in W/Ni-Co Composite after Rotary Swaging

“…Probably the most widespread SPD method is the equal channel angular pressing (ECAP) and its modifications (TCAP [9], TCMAP [10], NECAP [11], etc. ), which have been proven to refine effectively the grain size to the ultra-fine-grained (UFG) scale for various materials ranging from aluminium [12], through magnesium [13], copper [14], steel [15], and also tungsten [16,17]. However, ECAP is a discontinuous process, as the majority of SPD methods including the most effective methods of high-pressure torsion (HPT) [18] are, and is only suitable for processing samples of finite dimensions.…”

A Comprehensive Review on the Influence of Equal Channel Angular Pressing Parameters on Magnesium Alloys

“…It was reported that the channel angle, ɸ and curvature angle, Ψ affected to the strain present in each passes of ECAP. Iwahashi et al [53] and Vincentis et al [54], proposed the strain accumulated, ε N during the process which can be denoted as:…”

“…This model resolves that a higher value of channel angle will contribute to a higher strain value. In Vincentis work, the equivalent strain per pass obtained was 0.67 when 120° of die angle was used in ECAP process [54].…”

Investigation of microstructure and texture evolution of a Mg/Al laminated composite elaborated by accumulative roll bonding

“…Meanwhile, in FCC metals, the mechanism of grain refinement is characterized by the transformation of LAGBs to HAGBs with subsequent increase in strain [21,31]. However, grain refinement in FCC metals may also be correlated with dynamic recrystallization, which occurs in this case when high strains cause a decrease in LAGBs and an increase in HAGBs [37,38]. poles tilting slightly away from normal direction (ND) towards transversal direction (TD).…”