Enhanced grain refinement and mechanical properties in a severely plastic deformed Ni–30Cr alloy

The present study was carried out to evaluate the microstructures and mechanical properties of severely deformed Ni–30Cr alloys. Cross-roll rolling (CRR) was introduced as a severe plastic deformation (SPD) process. Ni–30Cr alloy sheets were cold rolled to 90% thickness reduction and subsequently annealed at 700 °C for 30 min to obtain the recrystallized microstructure. Electron back-scattered diffraction (EBSD) was introduced to analyze grain boundary character distributions (GBCDs). The application of CRR to the Ni–30Cr alloy effectively enhanced grain refinement through heat treatment; consequently, the average grain size was significantly refined from 33 μm in the initial material to 0.6 μm. This grain refinement directly improved the mechanical properties, in which yield and tensile strengths significantly increased relative to those of the initial material. We systematically discuss the grain refinement and accompanying improvement in mechanical properties in terms of the effective strain imposed by CRR relative to conventional rolling (CR).

► The application of cross-roll rolling to the Ni–30Cr alloy effectively enhanced grain refinement. ► This grain refinement in cross-roll rolling directly improved the mechanical properties. ► Particularly, yield strength increased to 470% relative to those of the initial material. ► We discussed the grain refinement in terms of the effective strain.