Abstract: Ela Resilence magnitude △α is a critical physical quantity with respect to the eleastoplastic deformation taking place in the course of steel strip formation. On the grounds of rather systematical and theoretical calculation a mathematic expression for the said elresilence very magnitude is provided and also, by means of appropriate approximation, an expression of △α which can be directly appliel to actual production is given. Besides, the paper involves a necessary discussion concerning the effect of elresilence very magnitude on the procuction of welded tubes.