42 research outputs found
Experimental research on the effect of induction reheating on the microstructure and mechanical properties of hot-rolled low-alloy steel plate
X-ray Microtomography Analysis of the Aluminum Alloy Composite Reinforced by SiC After Friction Stir Processing
Resonant pulsed electromagnetic stirring of melt for effective grain fragmentation
The paper describes the results of an experimental research, demonstrating and explaining the effect of grain fragmentation, caused by pulsed resonant electromagnetic stirring. In the experiments, 6082 aluminium alloy melt was directionally solidified under the influence of continuous (AMF) and pulsed application (PMF) of an alternating magnetic field. The frequency of applied PMF was in accordance to the low-frequency circulation of the melt, causing the resonant increase of a pulsed component of the melt velocity. The structure of electromagnetically stirred specimens was compared to those, solidified without a magnetic field. A strong fragmentation effect (decrease of an average grain size on 51%, comparing with the solidification in natural conditions) for the case of resonant EM stirring was stated. Further, to analyse the influence of the flow, appearing due to the resonant stirring, we observed the formation of solid/liquid interface and a macro-crystalloid structure during solidification of continuously and pulsed stirred melt by applying the novel method of neutron radiography. The results confirmed the strong influence of the pulsed component of velocity on thermal conditions during solidification and, consequently, the metal structure
Determination of heat treatment parameters for heavily - loaded aircraft engine components
Gears, due to their complex shape, carried load and required accuracy are ones of most complex aircraft engine
parts. Single tooth damage usually breaks the power transmission and causes failure of the entire gear system.
Adequate sustainability and guarantees of transmission is therefore a condition for secure operation of whole device.
Particularly high requirements for reliability are put to transmissions used in the aerospace industry. Due to the loads
which are transmitted through the gears, the materials used by the manufacturer must have not only high strength but
also show the abrasion resistance of the surface layer and the ductility of the core. Proper parameters matching
allows to create an element that can operate at higher stresses and loads. In addition, factor strength and abrasion
resistance of the surface layer has a significant impact on the life of the gear. Thermo-chemical treatment of industrial
gears is a fundamental process, which gives them adequate mechanical properties regarding loads they carry and the
surface conditions of work. Among many methods of thermo-chemical treatment used in the industry, the most
distinctive are innovative technologies designed to reduce process costs and being more environmentally friendly. The
most promising methods in the discussed field are vacuum carburizing and high-pressure hardening, which by their
specification of work significantly reduce the emission of CO2 and the duration of the process, without reducing the
quality of the final product. The main aim of the paper is to present criteria for selection of heat treatment parameters
as a part of thermo-chemical treatment process performed using vacuum methods. Proper heat treatment parameters
are crucial in programming of some of final material characteristics as grain size and retained austenite morphology