Effect of cool deformation in low carbon microalloyed steels

Cool deformation refers to deformation at very low temperatures (close to the 'coiling' temperature) which has been found to increase the strength of Nb microalloyed steels. This paper discusses the microstructure changes and possible strengthening mechanisms associated with this technique. Low carbon microalloyed steel specimens were heated to temperatures of 1200°C and held at temperature for 20 minutes. After this reheat, some specimens were aged at 400°C for times ranging from 10 minutes to 10 hours followed by air cooling. Others were subjected to deformation at 400°C ('cool deformation') prior to ageing. The mechanical properties of the heat treatment and cool deformed specimens were evaluated by shear punch tests at room temperature and precipitates were characterized by electron microscopy. By comparing the results of each series of tests, the influence of cool deformation is assessed. © Canadian Institute of Mining, Metallurgy and Petroleum.