High temperature plastic deformation of CuZn30 brass was investigated in the temperature range between 650 • C and 850 • C. Torsion tests were performed for experimental plan according to test array 5 × 4, i.e. five temperatures 650, 700, 750, 800, 850 • C and four speeds of torsion shear strain rate 0.5, 2.5, 12.5, and 25 s −1. Mathematical model has been developed to predict high-temperature shear stress behaviour of CuZn30 brass. Explicit equation, which is a function of peak stress, temperature and shear strain rate, was used in the mathematical model. There are four constants in the equation; one of those is the activation energy which for CuZn30 brass reaches the value Q = 180.3 kJ mol −1. Measured and calculated values of shear stress are shown in graphs in dependence on the value of deformation, where the temperature of deformation and the speed of deformation are the parameters for the particular curves. The predicted results are in accordance with the experimental curves stress-deformation that can be used to model the behaviour of hot extrusion pressing of CuZn30 brass.

Part production by deep drawing technology brings important economic advantages. Cupping test is used to determine material suitability for deep drawing. The main principle of the test is redrawing of cylinder metal test piece to the cup. The result of the test is calculation of limiting drawing ratio (LDR) which states the ratio between the largest blank diameter and final cup diameter. Many cupping tests for various materials were performed in order to determine maximal value of LDR that would still allow deep drawing without failure of material integrity.Paper presents the theoretical determination of the limiting drawing ratio (LDR) in dependence on d0/t0 ratio and friction coefficient between blank and punch.Limiting drawing ratio (LDR) converges to Euler's number (e) for high test piece depth and final cup diameter ratio values. Theoretical analysis of the cupping on drawing die with tractrix curve shows that maximal value of LDR may achieve value LDR>e. This is possible at lower values of test piece depth to final cup diameter ratio. Coefficient of friction has determining influence on LDR value.

The goal of the present work is to compare progressive technology -rolling at cryogenic temperature and classical rolling at ambient temperature followed by an investigation of their impact on the final microstructure and the magnetic properties of non-oriented electrical steel. Non-oriented electrical steel is characterized by high magnetic induction, low magnetic losses, and low coercivity. The best magnetic properties are achieved using preferable texture and optimal grain size. In this paper there is analyzed the percentage of different textural components after cryo-rolling and after rolling at ambient temperature. To obtain maps of inverse pole figures, the electron backscatter diffraction method was used. The main contribution of this study was that the samples rolled at cryo conditions and after final annealing reached better magnetic properties than at ambient temperature, which was reflected by low magnetic losses and coercivity.

The calculation of average material contact pressure to rolls base on mathematical theory of rolling process given by Karman equation was solved by many authors. The solutions reported by authors are used simplifications for solution of Karman equation. The simplifications are based on two cases for approximation of the circular arch: (a) by polygonal curve and (b) by parabola. The contribution of the present paper for solution of two-dimensional differential equation of rolling is based on description of the circular arch by equation of a circle. The new term relative stress as nondimensional variable was defined. The result from derived mathematical models can be calculated following variables: normal contact stress distribution, front and back tensions, angle of neutral point, coefficient of the arm of rolling force, rolling force, and rolling torque during rolling process. Laboratory cold rolled experiment of CuZn30 brass material was performed. Work hardening during brass processing was calculated. Comparison of theoretical values of normal contact stress with values of normal contact stress obtained from cold rolling experiment was performed. The calculations were not concluded with roll flattening.

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