Solid-state welding of ultrafine grained copper rods

Abstract

The article focuses on the Direct Drive Rotary Friction Welding of ultrafine-grained copper rods, which feature increased mechanical properties and good electrical properties, yet are limited in size. The use of UFG metals is often limited by the too small dimensions of semi-finished elements produced by SPD methods. Therefore, the production of finished machine parts from UFG metals is currently economically unjustified. Dismissal of dimensional limitations can be done by introducing joining to technological processes. The proposed joining method does not lead to a melting of the material in the joining zone or excessive degradation of the UFG microstructure. To obtain the best results, the research used the method of low-energy welding of two kinds of specimens: with a flat or a conical contact surface. In the article, the authors present, by means of metallographic microsections and microhardness measurements, the influence of rotational speed, welding pressure and conical shape contact surface on the quality of the obtained joints. The conducted research made it possible to obtain good quality joints whose microhardness is reduced only by about 10% in comparison with the base material and the tensile strength dropped from only 397–358 MPa.

Characterization of ultrafine-grained copper joints acquired by rotary friction welding

“…The resulting time of friction phase t T and total friction time t TC , defined as the sum of the friction and braking times, were calculated based on data acquired during the welding process. Based on previous research [26], a processing window of optimum conditions was chosen and samples were welded according to the parameters listed in Table 1. Two parameters were adjusted, i.e., rotational speed and friction phase pressure, which were in a range of 13,000-20,000 rpm and 2.5-4.5 bar, respectively, whereas the forging phase pressure was set at 5.5 bar.…”

Deep Convolutional Neural Network Algorithm for Prediction of the Mechanical Properties of Friction Stir Welded Copper Joints from its Microstructures

“…Various Machine Learning algorithms [9] are widely used in Friction Stir Welding process [10,11]. Friction Stir Welding process is a solid-state joining process [12,13] which is basically used to join the alloys which are difficult to weld by conventional welding process [14][15][16][17]. Friction Stir Welding process is governed by the input parameters such as Tool Rotational Speed (RPM), Tool Traverse Speed (mm/min) and an Axial Force (KN) [18][19][20].…”