Bauschinger Effect in Microalloyed Steels: Part I. Dependence on Dislocation-Particle Interaction

The Bauschinger effect (yield stress decreasing at the start of reverse deformation after forward prestrain) is an important factor in strength development for cold metal forming technology. In steels, the magnitude of the Bauschinger effect depends on composition, through the presence of microalloy precipitates, and prior processing, through the size and distribution of microalloy precipitates and presence of retained work hardening. In this article, the microstructures of two (Nb- and Nb-V-microalloyed) steel plates, in terms of (Ti,Nb,V,Cu)-rich particle distributions and dislocation densities, have been quantitatively related to the Bauschinger parameters for the same processing conditions. For the 12- to 50-nm effective particle size range, the Bauschinger stress parameter increases with the particle number density and dislocation density increase. The relative influence of these two microstructure parameters is discussed.