Improvement of mechanical properties in severely plastically deformed Ni

Improvement of mechanical properties in severely plastically deformed Ni–Cr alloy

Song, K.H. / Kim, H.S. / Kim, W.Y.

Highlights ► The application of cross-roll rolling to the Ni–20Cr alloy effectively enhanced grain refinement. ► This grain refinement in cross-roll rolling directly improved the mechanical properties. ► Particularly, yield strength increased to 800% relative to those of the initial material. ► We discussed the increase in mechanical properties in terms of the grain refinement and texture development.

Abstract This study was carried out to evaluate the grain refining and mechanical properties in alloys that undergo severe plastic deformation (SPD). Conventional rolling (CR) and cross-roll rolling (CRR) were introduced as methods for SPD, and a Ni–20Cr alloy was selected as the experimental material. The materials were cold rolled to 90% thickness reduction and subsequently annealed at 700°C for 30min to obtain the fully recrystallized microstructure. The annealed materials after cold rolling were assessed through electron backscattered diffraction (EBSD) analysis to investigate the grain boundary characteristic distributions (GBCDs). The CRR process was more effective than the CR process in developing grain refinement; the grain size decreased from 70μm in the initial material to 4.2μm (CR) and 2.4μm (CRR), respectively. The grain refinement affected mechanical properties such as microhardness, yield, and tensile strength, which were significantly increased relative to the initial material.