Effect of cooling rate on the microstructure and mechanical properties of a C-Mn-Cr-B steel

摘要

The microstructure and mechanical properties of a low carbon steel containing 30 ppm boron have been investigated. The steel was subjected to various cooling conditions in a thermo-mechanical simulator to generate continuous cooling transformation (CCT) diagram. Similar cooling conditions were also applied to tensile samples in order to evaluate their mechanical properties. The results indicate profuse banding in the hot strip of thickness 2.5 mm. This effect is attributed to the presence of manganese. In addition, variation in cooling rate led to increase in strength but severely affected percentage elongation albeit in an acceptable limit of 6%. This effect is discussed in the light of degree of banding of strips and microstructural constituents generated during heat treatment of steel strips of different thicknesses.