The Effect of ECAP Deformation Route on Microstructure, Mechanical and Electrochemical Properties of Low CN Fe-20%Cr Alloy

Abstract

The effect of the deformation route on the microstructure, and the mechanical and electrochemical properties of low CN Fe-20%Cr alloy by equal channel angular pressing, have been investigated focusing on the anisotropy of the microstructure. This alloy was pressed at 423 K from one, two and four passes via routes A, Bc and C, and the microstructure was observed in three orthogonal planes. As has been acknowledged, overall grain fragmentation proceeded most effectively in route Bc. However, the degree of anisotropy of microstructural development was different among the three deformation routes. The fractions of the high angle grain boundary and mean grain boundary misorientation were high and nearly isotropic in route Bc, whereas they were consi- derably low in one direction and highly anisotropic in routes A and C. Most importantly, those two parameters were the highest in route C if limited to the transverse direction (Y-plane), i.e. normal to both the insert and extruding directions. This result contrasted with FCC materials, which was reported by most papers having the highest fraction of high angle grain boundary (HAGB) in route Bc. Ultrafine grained structure with the highest HAGB on Y-plane in route C exhibited the most stabilized corrosion behavior.