Formation of the Cottrell atmosphere during strain aging of bake-hardenable steels

A model has been developed to describe the formation of the carbon atmosphe re around dislocations during the aging of a bake-hardenable steel, by taki ng into account the concurrent segregation of carbon atoms to dislocations, grain boundaries, and pre-existing cementite particles. The effects of the segregation of carbon to grain boundaries and to pre-existing cementite pa rticles on the formation of the carbon atmosphere have been discussed theor etically. Strain-aging experiments have been carried out with a vacuum-dega ssed ultra-low-carbon blake-hardening steel, and the experimental results b een compared with the theoretical predictions. It is shown that the model d eveloped can describe the formation of the carbon atmosphere around disloca tions in both low-carbon and ultralow-carbon bake-hardenable steels in indu strial processing conditions.