Transition from bainite to acicular ferrite in reheated Fe–Cr–C weld deposits

Abstract Factors controlling the transition from acicular ferrite to bainite in Fe–Cr–C weld metals have been investigated. It appears that the presence of allotriomorphs of ferrite at austenite grain boundaries has the effect of suppressing the formation of bainitic sheaves. This in turn allows the acicular ferrite plates to develop on intragranular nucleation sites. A theoretical analysis indicates that bainitic transformation is prevented from developing at the allotriomorphic ferrite/austenite boundaries by the carbon concentration field present in the austenite at the allotriomorphic ferrite/austenite interface. This field does not homogenise within the residual austenite during the time scale of the experiments.MST/1217

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