Wyniki 1-2 spośród 2 dla zapytania: authorDesc:"Piotr Okoniewicz"

Ocena efektów odpuszczania laserowego zahartowanego objętościowo żeliwa sferoidalnego DOI:10.15199/28.2015.6.15

  The evaluation of the effect of laser annealing of through hardened nodular iron Presented research results concern designing aspects of surface layer of cast iron parts. The aim of presented research was to estimate the possibilities of laser heating for annealing processes without appearing of the remelted zone or the zone hardened from the solid state near the surface. Laser treatment was performed with CO2 Trumpf TLF 2600 molecular laser with continuous wavelength. During the laser treatment surface temperature was recorded. The results of performed treatment were estimated on the base of microstructure analysis and microhardness measurements. The carried out research enabled to state, that the power densities which caused annealing processes (without reherdened zones presence) is 7.5 and 9·102 W·cm-2 (with thin hardened layer) for 3.74 s interaction time. The decrease of matrix microhardness in the surface layer was approx. 200 HV0.1. In case of application lower power density — about 5.5·102 W·cm-2 no microhardness changes was recorded. The results of presented research enable to state, that creation of annealed zone (as only one modified zone in surface layer) in case of hardened cast iron parts is possible by laser heating. However, it requires more precision in laser treatment parameters selection, than in case of treatments involving surface layer hardening. Key words: nodular iron, laser annealing, hardness. Prezentowane wyniki badań dotyczą konstytuowania warstwy wierzchniej elementów żeliwnych. Celem badań była ocena możliwości wykorzystania nagrzewania wiązką laserową do aktywowania procesów odpuszczania zahartowanego elementu bez pojawienia się przy powierzchni stref przetopionych lub ponownie zahartowanych ze stanu stałego. Obróbkę wykonano za pomocą lasera molekularnego CO2 Trumpf TLF 2600 o pracy ciągłej. Podczas obróbki rejestrowano temperaturę powierzchni nagrzewanego elementu. Efekty obróbki ocen[...]

Analiza efektów zużywania się wybranych obręczy kół tramwajowych w aglomeracji poznańskiej DOI:10.15199/28.2015.6.8

  The evaluation of wear effects of selected trams' wheels in the Poznan agglomeration The aim of presented research was evaluation of the main types of tram wheel wear of chosen rail vehicle and material changes which appear as a consequence of wheel and rail wear. Following tests was performed: macroscopic research, profile tests, Vickers hardness measurements, microscopic research with light microscope (Zeiss Epiquant with CCD), scanning electron microscope (Tescan Vega 5135) with X-ray microanalizer (PGT Avalon). The chemical composition was also checked with fluorescent spectrometer (LECO GDS 500A). The basic form of wear was shelling, which was detected by macroscopic research. The most damage surface was rolling surface. It has to be underline that the shelling was in early stage of growth. Created shells did not appear in the whole circumference of wheel and their size were relatively not huge. It is probably due to short distances characteristic for trams (in the comparison with trains). Moreover, in same regions of rolling surface, so called white layer was detected. It allows to state that sliding surfaces of wheel were (in a very small areas) heated in to higher temperature than it happens in case of shelling. Nonetheless, it was very local process, so it is rather not important in general wear of tested wheels. Tram wheels were highly deformed, particularly on the top of the edge of the wheel, and in the vicinity of outside angle of rolling profile. High deformation caused 70% hardness increase in comparison to the core material. In microstructure MnS was detected. Its presence in the surface layer of the top of the edge of the wheel caused delamination. It could help to crack initiation and, as a result, more intensive wear of tram wheels. Key words: tram wheel, wear, surface layer. Celem badań było określenie dominujących typów uszkodzeń obręczy wybranego pojazdu szynowego, a także zmian materiałowych będących wynikiem zuży[...]

 Strona 1