Research deals with determining the strain-rate sensitivity m and the activation energy for the superplastic deformation Q of a cold rolled aluminium Al-Mg-Mn-Sc alloy. The experiments were carried out under uniaxial tension over the temperature range 390 °C to 550 °C and at a constant strain rate or constant cross-head speed between 1×10-4 s-1 and 2×10-2 s-1. The m-values were determined on the basis of the true stress, true strain curves and also using the jump-test method. The m-values varied from 0.35 to 0.70, which depended upon the forming conditions.
COBISS.SI-ID: 1004639
Ag alloys with Te, Se and S fulfil the conditions for the internal oxidation. Microstructure of these alloys consists of matrix and particles of intermetallic compounds. At the direct oxidation of the particles of the intermetallic compound the phenomena of the selective oxidation was observed. Concentration of more reactive elements is increasing in the oxidized part of the particles of the intermetallic compound (Te in AgTeSe). In the precipitated oxide particles the concentration of Se is more than twice higher than of Te.
COBISS.SI-ID: 14376214
The creep behaviour of 9Cr-1Mo-0.2V (P91-type) steel was studied at elevated temperatures of 625 to 675 °C. Uniaxial creep tests were performed under constant load and constant stress at initial stresses of 120 to 240 MPa. For description of creep behaviour of P91-typ steel the improved stress-dependent, energy-barrier model was successfully used. The Monkman-Grant relation showed that the minimum creep strain rate is not quite inversely proportional to the time-to-rupture for both constant-load and constant-stress creep tests.
COBISS.SI-ID: 1076063
Nanostructures of two non-oriented electrical steels were investigated in order to elucidate the influence of nanostructure and its components on magnetic properties. Surprisingly, the sample with coarser ferrite grains exhibited higher core loss. For this reason (HR)TEM imaging was carried out. Precipitation reactions were monitored using DSC. Light microscopy, FE-SEM/EDX and EBSD analyses were also performed to analyse the microstructures and crystallographic textures. It was shown that the nanostructure and nanoprecipitates also have a crucial impact on the magnetic properties.
COBISS.SI-ID: 810154
The pinion from the drive of the cement mill was failed; the teeth cracked and spall occurred on the sides of several teeth. The failure was only located on one side of the pinion. This type of failure is common with surface-hardened gears. We have found that the failure of the pinion is a direct consequence of the incorrect geometry of the surface hardened layer. The lifespan of the pinion could have been extended if the whole surface of the faces and roots of the teeth had been hardened and if the hardening had been deeper.
COBISS.SI-ID: 1080159