Key Engineering Materials Vol. 682

Abstract: The paper presents the results of the study aimed at determination of plasticity of hard-deformed aluminium alloy grade 5019 in terms of parameters characteristic for the process of extrusion. The examinations were carried out in hot torsion test. Using the developed mathematical model of the analyzed alloy the mathematical modelling of torsion test was also performed.

Abstract: The paper present a method for determining the real steel work-hardening curves based on the cylindrical specimen compression test. The subject of testing were 5083 and 5754 aluminium alloy. The tests were carried out using the physical simulator of metallurgical processes GLEEBLE 3800 (Figure 1a) for the temperature range of 400 ÷ 560 °C and the strain rate range of 0,1 - 1,0s^-1. Based on plastic deformation parameters recorded during the experiment, mathematical processing, that is the digital filtration and approximation of the obtained testing results, will be performed. Then, using the inverse method, the actual values of the coefficients of the numerical models for the rheological properties of the tested materials will be determined.

Abstract: The paper present results of the research on the laboratory drawing process of zinc obtained in industrial conditions in the CCR by Properzi method. The force drawing, mechanical properties before and after process was measured and formability limit in drawing process was specified. Because the wire drawing process was on hot (above the recrystallization temperature) the material didn’t work hardening as a function of strain which reduces the ductility and breaking just after the die. The microscopic images of microstructure reveal the presence of large twins recrystallization reflecting the dynamic renewal structure.

Abstract: In this paper microstructure and creep properties of Mg-Al-Ca-Sr, Mg-Zn-RE-Zr and Mg-Sn-Si gravity casting magnesium alloys are presented. The microstructure was characterized using light microscopy, scanning and transmission electron microscopy. Phase identification was made by SAED and XRD analysis. Creep tests were carried out in the temperature range from 180°C to 200°C at applied stress of 60 MPa. Microstructure of Mg-Al-Ca-Sr alloys composed of α-Mg grains and C36, C15 and C14 intermetallic compounds in the interdendritic regions. In case of Mg-Zn-RE-Zr alloys the dominant intermetallic compound is (Mg,Zn)₁₂RE phase also located in the interdendritic regions. Microstructure of Mg-Sn-Si alloys after T6 heat treatment consists of plate-like precipitates of Mg₂Sn phase, primary crystals of Mg₂Si phase and globular Mg₂Si phase. Among the alloys in this study, the low-cost Mg-5Al-3Ca-0.7Sr alloy has the best creep resistance. The other alloys, excluding the Mg-5Si-7Sn alloy, are characterized by a poorer creep resistance in compared to Mg-5Al-3Ca-0.7Sr alloy, however their creep resistance is better if compared to typical Mg-Al alloys. Creep resistance of Mg-5Si-7Sn alloy is very low.

Abstract: Due to specific application of the Zn-Cu-Ti alloy rolled sheets as a roofing material, ready-made sheets has to meet some specific requirements of bendability at relatively low temperatures, as low as 5°C. In the current paper it was shown that susceptibility of the Zn-Cu-Ti sheets to low temperature bending, is closely related to degree of its dynamic recrystallization during rolling process. The paper discusses effect of different technological routes on the microstructure, mechanical properties and in particular the low temperature performance of Zn-Cu-Ti rolled sheets. The experimental results shows that the homogenization of Zn-Cu-Ti casted strips at the pre-rolling stage can play important role in recrystallization of the sheets during rolling. The current work is part of research on designing new technological route.

Abstract: In this article, the results of microstructure and hardness investigation performed on CuFe2 alloy processed by rolling with cyclic movement of rolls (RCMR) were presented. The investigations were focused on cross section planes of deformed samples. This results were compared with the ones obtained for samples after conventional rolling. It was shown that in the initial passes, the additional movement of rolls in RCMR method generate in material heterogeneous microstructure and hardness. With increase of deformation the microstructure and hardness distribution is more homogeneous.

Abstract: The paper presents the results of studies on obtaining the alloy and generating a set of very high mechanical and electrical properties of wires. The paper also presents the results of testing the rheological resistance in the form of stress relaxation tests carried out on the wires after various thermomechanical treatment processes. The optimum parameters of the thermo-mechanical treatment of the alloy were determined, enabling obtaining the most favorable mechanical and electrical properties of wires. The relationships of the influence of the material and its deformation on the changes in the mechanical and electrical properties of wires were determined. In addition, a microstructural analysis was carried out of casts and wires using scanning electron microscopy. Cast material was subject to observation and the material at successive stages of heat treatment.

Abstract: In the work, an original method and a special modified device is presented enabling to determine welding conditions of hard deformable aluminium alloys. The main advantage of the proposed method is that it simulates conditions occurring in the welding chamber of the porthole dies. The weldability tests were performed for 5754 (3,5% Mg) and 5019 (5,5% Mg) alloys, in a wide range of temperatures and pressures. The microstructure and joints strength were examined. The welding conditions of AlMg alloys that allowed obtaining high-quality joints were determined. The obtained welding stress values will be the basis for extrusion porthole die design.