An EBSD investigation of interstitial-free steel subjected to equal channel angular extrusion

作者：Gazder Azdiar A^*; Cao Wenquan; Davies Christopher H J; Pereloma Elena V

来源：Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2008, 497(1-2): 341-352.

DOI：10.1016/j.msea.2008.07.030

• Equal channel angular extrusion (ECAE)
• Equal channel angular pressing (ECAP)
• Electron back-scattering diffraction (EBSD)
• Coincidence-site-lattice (CSL)
• Steel
• Hall-Petch

The microstructural evolution of interstitial-free (IF) steel subjected to Phi = 90 degrees equal channel angular extrusion (ECAE) for up to 4 passes via routes A, B(A), C and up to 8 passes via routes B(C) was studied using electron back-scattering diffraction (EBSD). Routes B(C) and B(A) recorded the smallest grain size and aspect ratios and the largest average misorientation and area fraction of high-angle grain boundaries (HAGBs). During multiple passes, microstructure refinement continues until a convergence in effective subgrain and grain diameters occurs; following which the rate of HAGB formation reduces slightly. The percentage rise in the number of Sigma 3 and random boundaries should be correlated with the operation of recovery mechanisms in ultra-fine grained IF-steel rather than linking such special boundaries with twinning during ECAE. Compared to the scaling factor Hall-Petch (H-P) equation, the composite H-P equation indicates that although the low-angle grain boundaries (LAGBs) provide the maximum strengthening up to 8 passes, the contribution from HAGBs also increases with greater pass number.

• 出版日期2008-12-15