Pressing prismatic and screw profiles from copper M4

摘要

Pressing methods of prismatic and screw metallic profiles are considered. An example of cold pressing of a billet from copper M4 with the formation of a solid square-cross-section profile is presented. Conventional pressing (extrusion) and extrusion followed by torsion pressing (extrusion and screw pressing (ESP)) are compared by mechanical characteristics, energy intensity, and the destruction character of copper samples. Herewith, the ESP of the billet was performed in one facility during the united production process. Pressing prismatic and screw profiles for one pass at room temperature was performed for copper billets 11.7 x 60 mm. The billet was loaded with a puncheon with the help of a hydraulic press. After the deformation treatment, solid prismatic and screw copper profiles with a square cross section of 8 x 8 mm were formed. The results on mechanical properties, deformation regularities, and destruction mechanism during the uniaxial tension of the samples made of technical copper M4 in the delivery state and after hardening are presented. Mechanical tests for uniaxial tension of the samples with a working size of 3 x 15 mm were performed using an UTS-20k testing machine at a constant loading speed of 3.33 x 10(-5) m s(-1). A certain increase in the strength of copper subjected to extrusion for one pass at room temperature is established. Screw pressing after extrusion provides higher plasticity compared with the initial state and extrusion. A fractographic research of sample ruptures is performed using a Hitachi TM 3030 scanning electron microscope in the secondary electron mode. It is shown that the destruction mechanism of copper samples in the delivery state, as well as after extrusion and ESP, is qualitatively identical. The destruction of the samples of copper M4 both in the initial state and after the deformation treatment according to the specified modes occurred according to the viscous fracture mechanism. It is revealed that ESP-subjected copper possesses larger energy intensity in connection with an increase in plasticity. The rupture in a fibrous zone for the ESP-subjected sample differs by the tier arrangement of pit blocks. Large pits and micropits in all states of copper are present both in the fibrous zone and in the peripheral cut zone.