The Assessing of Mechanical Characteristics of the Steel Sheets Designed for Drawing for a Five-Month-Period as an Effect of Natural Ageing

Résumé

In the paper it is presented a study run on a five-month-period regarding the changes in the mechanical characteristics due to natural ageing for a drawing steel, cold rolled, unalloyed with 0.04% C. The ageing tendency of the sheets designed for drawing is influenced by the chemical composition and the steel purity on the one hand, as well as by the structural state and on stress state. In order to determine the mechanical characteristics and the Erichsen parameter, specimens with the following dimensions were used: length l₀ = 240 mm; width b₀ = 20 mm; thickness h₀ = 1.5 mm.

The following mechanical properties were determined: the yield point Rp0.2[N/mm²], the breaking strength Rm[N/mm²], the breaking elongation [%], the Erichsen parameter IE [mm]. In order to characterize the material’s quality with the objective of creating some marks it is useful to be studied besides the conventional set of trying, other parameters, as well, such as the drawing capacity with the help of the cold-hardening coefficient n.