A study was conducted to investigate conditions for grain boundary bulging during tempering of lath martensite in ultra-low carbon steel. The conditions for grain boundary bulging was discussed in terms of the mobility of grain boundary and the driving force for grain boundary migration. An ultra-low carbon steel with a chemical composition of Fe-1 .55Mn-O.OO2Si-O.0 1 P-0.0 I 5S-0.009C--O.0029N-0.0015B was used to conduct the investigations. Manganese (Mn) and boron (B) were added to obtain fully lath martensitic structure by enhancing the quench hardenability. The ingot produced by induction melting in an Ar gas atmosphere was homogenized at 1 473 K for 18 ks and hot-roiled to 50% reduction in thickness at 1 273 K. The microstructure was observed with an optical microscope (OM) and the distribution of the crystallographic orientation in the microstructure was examined by the electron back scattering diffraction (EBSD) method with a field-emission scanning electron microscope.
All Science Journal Classification (ASJC) codes
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry