Kinetics of cold work embrittlement in rephosphorised, interstitial free steels

The kinetics of cold work embrittlement, associated with grain boundary segregation of P in batch annealed interstitial free steels, was determined from the temperature–time cycle of the batch annealing process. The grain boundary segregation predictions were subsequently extended to a hypothetical optimised steel chemistry, where C effectively displaced P from the grain boundary through a site competitive interaction process. The P–C, site competitive process was expected to minimise the cold work embrittlement phenomena experienced in interstitial free steels. From a comparison of grain boundary P segregation, it was possible to draw conclusions concerning the minimum grain boundary P level that can be achieved through appropriate modification of the batch annealing cycle or by optimisation of the steel chemistry.