High-Temperature Deformation Behavior of MnS in 1215MS Steel

The effect of manganese sulfide (MnS) inclusions on the machinability of free-cutting steel is based on their morphology, size and distribution. Furthermore, the plasticity of MnS is high during the hot working caused different characterization of MnS. In this study, the deformation behavior of MnS in 1215MS steel after a thermomechanical process was investigated at 1323 K. The microstructures of MnS inclusions were characterized by optical microscopy, scanning electron microscopy, energy-dispersive spectrometry, and electron backscattering diffraction (EBSD). As the thickness reduction of the inclusions increased from 10 to 70%, their average aspect ratio increased from 1.20 to 2.39. In addition, the deformability of MnS inclusions was lower than that of the matrix. The possible slip systems of A, B, C, and D plane traces were \(\left( {\bar{1}0\bar{1}} \right)\left[ {\bar{1}01} \right],\left( {10\bar{1}} \right)\left[ {101} \right],\left( {011} \right)\left[ {01\bar{1}} \right]\), and \(\left( {110} \right)\left[ {1\bar{1}0} \right]\). Furthermore, the EBSD measurements suggested that slip planes in MnS inclusions occur on {110} planes.