Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7977645 | Materials Science and Engineering: A | 2015 | 53 Pages |
Abstract
In the present study, the effect of four-layer accumulative roll bonding (ARB) process at room temperature on the microstructure and mechanical properties of steel-based composite was investigated. Microstructural observations were done by scanning transmission electron microscopy (STEM). Also, textural evolution during the ARB process was evaluated using X-ray diffraction. It was found that occurrence of discontinuously dynamic recrystallization (DDRX) in the interstitial free (IF) steel during cold plastic deformation is possible. The four-layer ARB process at room temperature in the presence of SiC microparticles provided the stored energy required for DDRX in the IF steel with high stacking fault energy (SFE). On the other hand, hindrance of initial grain boundaries to dislocation movement resulted in DDRX grains along initial grain boundaries in the IF steel matrix. Average grain size of the final sample was 73Â nm but the microstructure was relatively inhomogeneous. The results also indicated that particle stimulated nucleation (PSN) promoted texture randomization in the steel-based composite. Dislocation density of the samples was determined from hardness measurement. The dislocation density increased continually until the dislocation density of the steel-based composite after fourth cycle was about 5.3 times (10.73Ã109Â cmâ2) higher than that of the initial sample (2.02Ã109Â cmâ2). Also, significant increase in dislocation density occurred after first cycle and in the final cycles the dislocation density value was saturated. After first cycle, a remarkable improvement was observed in the yield strength value, from 84Â MPa to 682Â MPa which is almost 8.1 times greater than that of the initial sample. After final cycle, the yield strength value increased to 1061Â MPa. Finally, the contribution of individual mechanisms such as the grain refinement, dislocation, second phase, and precipitation in strengthening of the IF steel was evaluated. The contribution of grain refinement and precipitation to the improvement in yield strength was maximum (~67%) and minimum (~3.2%), respectively.
Related Topics
Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
Roohollah Jamaati, Mohammad Reza Toroghinejad, Sajjad Amirkhanlou, Hossein Edris,