Carbide precipitation in low carbon niobium steel containing manganese and chromium

Precipitation of NbC inferrite has been examined in a low C (0·03 wt-%) steel in which the austenite-ferrite transformation kinetics has been slowed down substantially by the combined addition of 2%Mn and 4%Cr. This has enabled the carbide precipitation sequence at 700°C to be defined more precisely, starting with precipitation on dislocations, followed by interphase precipitation and, finally, carbide free ferrite. At 650°C the formation at the γ/α interface of V-shaped carbides and also the growth of carbide fibres have been related to the morphology of the interfaces. The retardation of the γ–α transformation by alloying additions encouraged the growth of these alternative carbide morphologies.MST/1158