Effect of Titanium Carbide Inclusions on Morphology of Low-Carbon Steel Martensite

The effect of titanium carbide (TiC) on morphology of low-carbon steel martensite was studied by means of electron backscatter diffraction (EBSD). The nucleation and growth of new morphology subunits such as packet, block and sub-block are observed in the area surrounding of micron-sized TiC particles. The misorientation from a fitted orientation relationship between martensite and austenite near TiC particle is larger than the average misorientation with a localized characteristic. The position of new morphology subunits has a well correspondence with the area in vicinity of TiC particle, which has large misorientation. The micron-sized TiC particle plays a role of stress concentrator in austenite during martensitic transformation which suppresses growth of one martensite variant while stimulates nucleation and growth of another one.