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Gliwice, Poland

The aim of the study was to investigate the effect of vibration welding parameters on the structure ofwelding region in polyamide 66 joints. The quality of jointswas examined under an optical microscope using polarized light. Differential scanning calorimetry (DSC) was used to study the influence of welding parameters: vibration amplitude (a),welding pressure (pz) andweld time (tz) on the melting temperature and the crystalline phase content in the weld as well as the base material of the joints. For low welding pressure and amplitude values, an amorphous phase was dominant in the welding region (Fig. 6a), while for higher values of these parameters an increase in the crystalline phase contentwas observed (Fig. 7). The mechanical strength of PA 66 joints was evaluated using a static tensile test (Table 3). Maximum tensile strength was in the range of 70 to 77 % of the value for the base material.

Klobcar D.,University of Ljubljana | Kosec L.,University of Ljubljana | Pietras A.,Instytut Spawalnictwa | Smolej A.,University of Ljubljana
Materiali in Tehnologije | Year: 2012

A study was made of the weldability of 4-mm-thick aluminium-alloy 5083 plates using friction-stir welding. A plan of experiments was prepared based on the abilities of a universal milling machine, where the tool-rotation speed varied from 200 r/min to 1250 r/min, the welding speed from 71 mm/min to 450 mm/min and the tool tilt angle was held constant at 2°. The factors feed per revolution (FPR) and revolution per feed (RPF) were introduced to get a better insight into the friction-stirring process. Samples for microstructure analyses, Vickers micro-hardness measurements and special miniature tensile-testing samples were prepared. The microstructure was prepared for observation on a light microscope under a polarised light source. A set of optimal welding parameters was determined at a FPR of 0.35 mm/r, at which quality welds can be made with a minimal increase in the weld hardness and an up to 15 % drop in the tensile strength.

The paper deals with an investigation of technological possibilities to produce T-joints of Al 6082 by friction stir welding technique and mechanical properties of the joints. It was indicated the importance of preparation proper welding stand by showing joints quality, presented on macrostructures, obtained with and without specially designed equipment for welding T-joints. Different ways of base metal preparation prior to welding (T-joints welded as two pieces and as three pieces), as well as two various shapes of steel dies directly forming the shape of tee connections, were used in experiments. It was shown how welding conditions influence structure and static properties of friction stir welding joints. Results show that for specified tool speeds significant imperfections, like voids, were formed. The best experimentally defined welding parameters, ensures lack of voids, were used to produce test joints for fatigue test. For the tested friction stir welding T-joints the fatigue category FAT were determined and compared to FAT categories of equivalent T-joints welded by conventional fusion welding. The study reveals also metallographic macroscopic and microscopic examination results, indicated typical imperfections arising during friction stir welding process of T-joints, as well as results of hardness measurement of joints cross section. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Weglowski M.S.,Instytut Spawalnictwa
Key Engineering Materials | Year: 2013

The effect of rotational and travelling speeds and down force on the torque in Friction Stir Processing (FSP) process are presented. To find a dependence combining the spindle torque acting on the tool with the rotational speed, travelling speed and the down force, the artificial neural networks have been applied. Studies have shown that the increase in the rotational speed causes decrease in the torque while the increase in the travelling speed and down force causes the increase in the torque at the same time. The relationship between parameters of the process and the temperature of the tool, based on measurement head TermSTIR, were presented. Tests were conducted on casting aluminium alloy AlSi9Mg. Application of FSP process resulted in a decrease in the porosity in the modified material and microstructure refining. Copyright © 2013 Trans Tech Publications Ltd.

Pilarczyk W.,Silesian University of Technology | Pilarczyk A.,Instytut Spawalnictwa
Materiali in Tehnologije | Year: 2015

The primary objective of the article is to present an innovative workstation and the test results related to iron-based bulk metallic glasses made by pressure casting into a copper die that is cooled with Peltier modules. A production of bulk metallic glasses by pressure casting into a copper die, including an innovative cooling method is presented in this article. The equipment for the casting, including a modern high-frequency induction heater and a control-measuring apparatus, which enables the repeatability and maintenance of the process parameters, is discussed. Semiconductor Peltier modules for cooling the molds are presented. The tests show that the semiconductor Peltier modules are a suitable substitute for the water cooling of the molds. They enable the casting at 0 °C of the molds. Additionally, the ecological and economic aspects of the introduced new methods are presented. The application of the innovative cooling technology also has an influence on a simplification of the equipment construction for the casting process. The test results for the bulk metallic glasses based on iron and obtained with the designed devices are presented in this paper. A structure analysis using X-ray examination and microscopic observation was performed. The diffraction pattern and microscopic observation revealed that the studied as-cast Fe-Co-B-Si-Nb alloy is in the amorphous state. The test results confirmed the amorphous structure of the obtained materials.

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