Investigation of Hardening Curves and Mechanical Properties of Copper Alloy M0 Depending on the Degree of Deformation During Cold Rolling of Strips

The chemical composition of M0 grade copper strips obtained at the Dong Nai machine-building plant (Vietnam) has been studied. The results of tensile testing of the samples of such strips are presented, which made it possible to determine the deformation resistance (yield strength), ultimate tensile strength, and percent elongation before and after rolling with a percent reduction of the cross-section area of ε = 10–30%. Based on the obtained data, curves were constructed that allowed us to establish quantitative trends in the variations of metal deformation resistance (yield strength) (σ_s), ultimate tensile strength (σ_t), and percent elongation (δ) depending on the degree of deformation of copper M0. It is shown that the ultimate tensile strength (σ_t) and yield strength σ_0.2 (σ_s) increase with different intensity as the percent reduction increases. The σ_t parameter demonstrates a slow linear monotonic increase from 221 to 315 MPa as the percent reduction changes from 0 to 30%; while σ_0.2 (σ_s) increases intensively according to the parabolic law from 41 to 308 MPa. The ductility index decreases from 63 to 16% within this deformation range. Regression equations have been obtained for calculating the basic mechanical properties of copper M0 during the process of cold rolling at various reductions. The adequacy of the obtained equations, confirmed by high correlation coefficient values (R² > 0.9), makes it possible to recommend them for calculating the power characteristics of the rolling process, as well as for use in the automated design (CAD) systems to determine the rational copper strips (M0) deformation conditions at the industrial sheet rolling mills.