The Role of Cold Rolling Reduction on the Microstructure and Mechanical Properties of Ultra-Low Carbon Bainitic Steel

Abstract

The present study investigates the microstructure and mechanical properties of ultra-low carbon bainitic steel (UCBS) under different cold rolling reductions. When the rolling reduction ratios were increased to 80%, the microstructure was refined, and the lath width of the bainite decreased from 601 nm to 252 nm. The ultimate tensile strength and yield strength increased from 812 MPa and 683 MPa to 1195 MPa and 1150 MPa, respectively, whereas the elongation decreased from 15.9% to 7.9%. In addition, the dislocation density increased from 8.3 × 1013 m−2 to 4.87 × 1014 m−2 and a stronger γ-fiber texture was obtained at the 80% cold rolling reduction ratio. The local stress distribution and kernel average misorientation were not uniform and became more severe with increased rolling reduction ratios. The strength increment of UCBS was primarily due to boundary strengthening and dislocation strengthening. The theoretical strength increment agreed well with the experimental measurements, which can be helpful for the design and production of UCBS for broad engineering applications.

Strengthening of 0.18 wt % C Steel by Cold Differential Speed Rolling

“…Rolling is the most widely employed metal forming process. Thus, various studies on the rolling process have been reported until now [ 1 , 2 , 3 , 4 , 5 ]. In recent years, differential speed rolling (DSR) has been regarded as one of the asymmetric rolling (ASR) methods in which the metallic or composite sheets were deformed between two distinctive rolls with different dimensions or speeds.…”