Precipitation hardening stainless steel 17-7PH with modified chemical composition was heat treated by modified RH950 condition. In this paper is presented the results of tests of microstructure and mechanical properties of precipitation hardened stainless steel 17-7PH with modified chemical composition, heat treated in modificated RH950 conditions. Regression analysis showed which variables are statistically significant in predicting the value of mechanical properties of the steel 17-7PH chemically modified composition.

In this paper, the microstructure of Cu82.3Al8.3Mn9.4 (in wt. %) shape memory alloy after hot and cold rolling was investigated. The Cu82.3Al8.3Mn9.4 alloy was produced by a vertical continuous casting method in the form a cylinder rod of 8 mm in diameter. After the casting, hot and cold rolling was performed. By hot rolling a strip with a thickness of 1.75 mm was obtained, while by cold rolling a strip with a thickness of 1.02 mm was produced. After the rolling process, heat treatment was performed. Heat treatment was carried out by solution annealing at 900 °C held for 30 minutes and water quenched immediately after heating. The microstructure characterization of the investigated alloy was carried out by optical microscopy (OM), scanning electron microscopy (SEM) equipped with a device for energy dispersive spectroscopy (EDS). Phase transformation temperatures and fusion enthalpies were determined by differential scanning calorimetry (DSC) method. The homogenous martensite microstructure was confirmed by OM and SEM micrographs after casting. During rolling the two-phase microstructure occurred. Results of DSC analysis showed martensite start (M s ), martensite finish (M f ), austenite start (A s ) and austenite finish (A f ) temperatures.

In this work the corrosion behaviour of Ni-Ti (Nitinol) shape memory alloy was studied using different electrochemical techniques including open circuit potential (EOC), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Samples made from nitinol alloy with diameter of 4 mm were used for microstructural and corrosion investigations. Testing solution was 0.9 % NaCl solution at pH=7.4, and temperature 37 °C. Microstructural analysis was performed by the optical and electron scanning microscopy (SEM) equipped with energy dispersive spectrometry (EDS). High values of the oxide film resistance (Rox) and the low value of corrosion current density (icorr) indicated high corrosion resistance of Ni-Ti alloy, but relatively low value of breakdown potential (Eb) indicates the possibility of development localised corrosion attack on the alloy surface. Size of pits was from 10 to 100 m and surface inclusions were initiation sites for the pitting corrosion.