Papers by Author: Artur Sitko

Abstract: This paper presents investigation of cavitation erosion resistance of nitrided austenitic stainless steel X5CrNi18-10. The diffusion layers were produced by using different parameters of reactive atmosphere (N₂:H₂). The microstructure, chemical composition and phase identification of the modified layer were examined using scanning electron microscopy, glow-discharge optical emission spectrometer and X-ray diffractometry, respectively. Cavitation erosion resistance of produced surface layers was investigated in a rotating disc facility. As a property characterizing the cavitation erosion resistance of manufactured surface layers were proposed incubation period and mass loss after 330 min of cavitation test. It was found that cavitation erosion resistance of modified surface layers is lower than reference material (not treated X5CrNi18-10 stainless steel).

Abstract: This paper presents investigations of nitrided cases after the glow-discharge nitriding process. The nitrided cases were obtained by using a different chemical composition of gas mixture at the temperature of 450^OC. The glow-discharge nitriding process was carried out on austenitic stainless steel, grade of steel X5CrNi18-10. The chemical composition and phase identification of the nitrided cases were examined by using the glow-discharge optical emission spectrometry (GD-OES) and X-ray diffractometry (XRD)

Abstract: This paper summarizes the results of experimental studies in which the aluminum alloy AW7075-T651 was friction stir welded (FSW) using various combinations of process parameters (rotational - R and travel speed - T). Mechanical properties of the test welds were assessed by using static tensile test and Vickers hardness measurement. The temperature of the welded plates was monitored during welding by means of thermocouples placed on both sides of the joint line, 15 mm from the weld axis as well as by using thermo camera. The microstructure, chemical composition and phase identification of the welding joints were examined using optical and scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffractometry (XRD). Investigations revealed that the temperatures at the weld center can reach values close to 550 °C and raised with R/T ratio increasing. It was found that tensile strength of welded joints is not correlated with R/T ratio and averages about 60% to 80% of tensile strength of a base material AW7075-T651. XRD analysis demonstrated that there is also deformation texture in the nugget (WN) and the thermo-mechanical affected zone (TMAZ) with strong dependence on process parameters.

Abstract: This paper presents investigation of surface layers. The diffusion layers were produced by using different parameters of reactive atmosphere (N2:H2). The research of the surface layers was performed using scanning electron microscope (SEM). The results of energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD) analysis are presented. Research reveals the influence of chemical constitution of reactive atmosphere on the change of properties of nitrided layers.