Abstract: In order to study the physical meaning and application of Lode parameter in depth，expression of relation between Lode parameter and invariants of the deviator J2, strain increment is deduced by theoretical analysis. The inherent relation between stress state and metal flow behavior of transient deflection is revealed through analyzing the relationship between Lode parameter and complexity of the plastic deformation, type of deformation. With examples of typical plastic process, distribution of Lode parameter’s value determines type of deformation, and this provides a theoretical basis for the quantitative analysis of metal flow behavior of plastic deformation. It has important significance to the analysis of metal plastic forming and its application.

Key words: Deformation type, Lode parameter, Metal flow, Strain increment