Influence of the two-stage plastic deformation on the complex of the magnetoacoustic characteristics of low-carbon steel and diagnostics of its structural state

Abstract

Magnetic, ultrasound and magnetoacoustic properties of low-carbon steel subjected to cold plastic deformation by rolling with different compression and subsequent flat pressing have been investigated. The hardness and coercive force are changing non-monotonically with deformation degree increase determined by cross-section change. Change of shape during flat pressing leads to the partial softening of the samples that lost flatness during rolling. The coercive force increases at low deformation degrees and has a maximum at 6% deformation degree and monotonously decreases with increasing of the deformation degree up to 20%. Peculiarities of hardness and magnetoacoustic properties are related to the change of dislocation structure and relaxation of longitudinal compressive stresses.The softening of the material can be detected by the amplitude of the parameter interrelated with the shape of the major hysteresis loop. The parameter proportional to the field of the maximum of magnetoacoustic emission can be a diagnostic parameter of the resulting hardening of steel under study as a result of two-stage plastic deformation.