The paper introduces a model for the formation mechanism of a stable system of stationary waves during submerged arc welding by considering the kinematics of the displacement and vibration of the electrode wire within the oscillating system. Analytical results were in good agreement with experimental results obtained on naval steel sheets. The advantages of ultrasonic welding to classical welding have been emphasized by means of the mechanical characteristics

The paper analyses the precipitation of γ2 phase within the γ'1 thermally induced martensitic matrix of five Cu-Al-Ni-Fe-Mn shape memory alloys (SMAs), by means of differential scanning calorimetry (DSC) thermograms, optical microscopy (OM) and scanning electron microscopy (SEM). It has been proved that the flat exothermic peaks, occurring during the heating of martensitic specimens, correspond to the formation of γ2 phase precipitates, which

The paper analyses the reproducible behaviour of three work generating applications of shape memory electric actuators, trained for two way shape memory effect (TWSME) in bending. The first is a lifting device, the displacement-temperature variation of which is considered as a function of time while revealing the influence of applied load. The second is an electric circuit breaker (disjunctor) for electric overload protection, the functioning of

The friction reversion mechanism during ultrasonic vibration drawing (UVD) of wires has been detailed for the case when the die is located at the oscillation maxima of the waves and actuated parallel to the friction force direction. The decrease of the drawing force for the UVD technology as compared to classical drawing has been explained by means of the intermittent contact in the metal-die forming area. A relationship has been derived fro the

The effects of presence of Nb and C in solution or in the form of NbC precipitates on the transformation of binary Fe-17mass%Mn alloys were evaluated from micro structural and macroscopic point of view. At microstructural level precipitation of NbC was accompanied by the decrease of both relative amount of & martensite and martensite plate thickness. The precipitation was associated with a general increase of proof stress and thermal hysteresis on

The behavior of helical springs made from lamellar specimens of Cu-Zn-Al shape memory alloy, which were martensitic at room temperature, was analyzed in force-elongation-temperature space. The study revealed the dependence of two forms of shape memory effect (SME): (i) work-generating SME and (ii) constrained-recovery SME, upon applied load and elongation, respectively. The tensile behavior of the springs, on loading between the austenite-start and

The structure of a Cu-13.67Al-4.28Ni-0.54Mn-0.14Fe (wt.%) shape memory alloy was analyzed in the initial condition, during a heating-cooling cycle, and during a room temperature loading-unloading mechanical cycle. A fully reversible martensitic transformation was revealed which was associated with a shape recovery degree reaching a saturation value at 97.7% for a relative permanent deflection of 90 %. By X-ray diffraction, the occurrence of a reduced

The paper reports some austenitization effects on the -phase morphology in a tempered martensitic Cu-21.57 Zn-7 Al (wt.%) shape memory alloy (SMA). By means of differential scanning calorimetry, X-ray diffraction and optical and electron microscopy, it has been shown that the effects of the stress-state induced in austenite persist even after martensitic transformation and tempering at 773 K. The two analyzed austenitization states, hot-pressed

In order to explain the stabilised shape memory behavior observed during the thermal and mechanical cycling of a Cu-14.86Zn-5.8Al-0.5Fe (wt.%) alloy, x-ray diffraction and optical microscopy studies have been performed. The former have shown that the previously reported reorientation of the alpha brass phase crystallites from alpha (111) to alpha (200), observed during the heating up to 500 deg C, also occurs duing a complete heating-cooling cycle

During the heating up to 500 C of a Cu-Zn-Al based Shape Memory Alloy, a marked texturing effect, caused by the preferred formation of the a-phase has been revealed by means of X-ray diffraction and DTA. Kinetic analyses were also performed.