Utjecaj Nb i Ti na mikrostrukturu i mehanička svojstva lijevanog čelika 30 % Ni / 18 % Cr nakon žarenja

The study discusses the microstructure and mechanical properties of eight tested 0.3 % C -30 % Ni - 18 % Cr cast steels stabilized with niobium and titanium after annealing in the cycle of 900 °C / 300 h. The niobium content in the cast steels varied from 0.0 to 2.0 % and that of titanium from 0.0 to 1.2 % by weight. Microstructure was examined using both light microscope and a scanning electron microscope with Link IS-IS attachement as well as an X-ray diffractometer. Depending on the chemical composition of cast steel, the following phases were identified: carbides of MC and M23C6 type and a phase rich in silicon, nickel, niobium and / or titanium, which was supposed to be a phase G. Relationships between the microstructure and mechanical properties of cast steel at 20 and 900 °C were examined as well.Studija raspravlja o mikrostrukturi i svojstvima osam testiranih lijevanih čelika - 0,3% C, 30 % Ni, 18 % Cr stabiliziranih niobijem i titanijem nakon žarenja u ciklusu od 900 °C / 300 h. Težinski udio niobija u lijevanim čelicima je varirao od 0,0 do 2,0 % a titanija od 0,0 do 1,2 %. Mikrostruktura se ispitivala i svjetlosnim mikroskopom i skener-elektronskim mikroskopom s priključkom na link IS-IS kao i na rentgenski difraktometar. Ovisno o kemijskom sastavu lijevanog čelika, identificirane su slijedeće faze: karbidi tipa MC i M23C6 i faze bogate silicijem, niklom, niobijem i / ili titanijem, a koju se smatra da je faza G. Također se ispitivao i odnos između mikrostrukture i mehaničkih svojstava lijevanog čelika na temperaturi od 20 i 900 °C

Influence of stubble intercrop growing on spring barley production profitability

Przedstawiono analizę i ocenę ekonomiczną technologii produkcji jęczmienia jarego z zastosowaniem międzyplonu ścierniskowego w postaci facelii błękitnej. Badania przeprowadzono w latach 2006-2009, w gospodarstwie rolnym w województwie zachodniopomorskim. Zakres realizowanych badań obejmował analizę i ocenę technologii produkcji jęczmienia jarego i facelii błękitnej, analizę struktury kosztów produkcji, kalkulację kosztów produkcji, obliczenie nakładów pracy oraz określenie poziomu opłacalności stosowania międzyplonu ścierniskowego. Z przeprowadzonych badań wynika, że stosowanie międzyplonu ścierniskowego zwiększa dochodowość uprawy jęczmienia jarego nawet o 93%.The paper presents analysis and economic assessment of spring barley production technology with application of stubble intercrop in the form of tancy phacelia. The research was carried out in 2006 - 2009 on farms of Zachodniopomorskie Voivodship. The scope of research included the analysis and assessment of spring barley and tancy phacelia production technology, analysis of production cost structure, calculation of production costs, calculation of labour amount and determination of profitability level of stubble intercrop application. Completed research proves that stubble intercrop application increases profitability of spring barley growing of even 93%

Mechanical properties of phase constituents in selected grades of cast steel

The nanoindentation measurements performed on three cast steels of 0.3C-30Ni-18Cr type with various content of niobium and titanium were carried out. Mechanical properties of the main phase constituents of the alloys, such as austenite, MC and M23C6 type carbides, were determined and analysed. The values of hardness (H) and Young modulus (E) for the austenite matrix were similar within the tested alloys. Essential differences (H=12÷24 GPa; E = 250÷400 GPa) were found between the carbide p hases p resent in tested alloys. The nanoindentation measurement on small particles is affected by different effects. One of these effects was excluded using numerical simulation of impressing the phase constituent into the matrix during indentation. The values of H and E obtained from simulation were: 30/450 GPa for NbC; 50/580 GPa for TiC; and 19/320 GPa for Cr23C6 respectively

Casting of Hearth Plates from High-chromium Steel

The paper presents the results of studies on the development of manufacturing technologies to cast hearth plates operating in chamber furnaces for heat treatment. Castings made from the heat-resistant G-X40CrNiSi27-4 steel were poured in hand-made green sand molds. The following operations were performed: computer simulation to predict the distribution of internal defects in castings produced by the above mentioned technology with risers bare and coated with exothermic and insulating sleeves, analysis of each variant of the technology, and manufacture of experimental castings. As a result of the conducted studies and analysis it was found that the use of risers with exothermic sleeves does not affect to a significant degree the quality of the produced castings of hearth plates, but it significantly improves the metal yield

Casting of Hearth Plates from High-chromium Steel

The paper presents the results of studies on the development of manufacturing technologies to cast hearth plates operating in chamber furnaces for heat treatment. Castings made from the heat-resistant G-X40CrNiSi27-4 steel were poured in hand-made green sand molds. The following operations were performed: computer simulation to predict the distribution of internal defects in castings produced by the above mentioned technology with risers bare and coated with exothermic and insulating sleeves, analysis of each variant of the technology, and manufacture of experimental castings. As a result of the conducted studies and analysis it was found that the use of risers with exothermic sleeves does not affect to a significant degree the quality of the produced castings of hearth plates, but it significantly improves the metal yield

Materials for Reformer Furnace Tubes. History of evolution

The paper discusses progress that has been made over the past sixty years in increasing the service life of centrifugally cast, creepresistant tubes operating in reformer furnaces. Attention was mainly focused on the principles of selection of the chemical composition of castings to improve their creep behaviour. The reasons accounting for withdrawal of tubes from service were indicated. Examples of chemical composition and mechanical properties obtained in creep-resistant Ni-Cr cast steel used by the leading European tube manufacturers were stated. Trends in current research aiming at further improvement of the tube performance characteristics were mentioned

Badania laboratoryjne nowego systemu regulacji dawki cieczy aplikowanej przez opryskiwacz polowy

The article presents an initial assessment of the new regulatory system of a spray dose adjustment system for field sprayers. In contrast to traditional sprayers, the proposed solution incorporates triple interlocked with diversified liquid expense nozzles controlled based on the dose adjustment process utilizing the forward and angular velocities of the machine. The adjustment system was tested using data gathered from monitoring the movement of a sprayer performing chemical plant preservation. The results prove that the system enables a substantial improvement in the surface distribution of the spray dose. Compared to the aforementioned traditional sprayer, where only 57.2% of measuring points have shown the spray dose being within 80-120% of nominal range, using the proposed solution the proper dose constituted 93.6% of all results.W artykule przedstawiono wstępną ocenę nowego systemu regulacji dawki cieczy aplikowanej przez opryskiwacz polowy. W porównaniu z tradycyjnym opryskiwaczem, w prezentowanym rozwiązaniu zamiast pojedynczych rozpylaczy zastosowano zblokowane rozpylacze trójelementowe o zróżnicowanym wydatku cieczy, sterowane w oparciu o proces regulacji dawki wykorzystujący wyniki dotyczące prędkości postępowej i kątowej maszyny. System regulacji przetestowano wykorzystując dane zebrane podczas monitorowania ruchu opryskiwacza realizującego chemiczną ochronę roślin. Uzyskane wyniki dowodzą, że system umożliwia znaczną poprawę rozkładu powierzchniowego dawki cieczy. W porównaniu z pracą monitorowanego na polu opryskiwacza, gdzie jedynie 57,2% punktów pomiarowych wykazywało dawkę cieczy należącą do zakresu 80-120% dawki nominalnej, przy użyciu proponowanego rozwiązania właściwa dawka cieczy stanowiła 93,6% wszystkich wyników

Cast Steels for Creep-resistant Parts Used in Heat Treatment Plants

Creep-resistant parts of heat treatment furnaces are in most cases made from high-alloyed chromium-nickel and nickel-chromium ironalloys, both cast and wrought. This paper presents the types of casting alloys used for this particular purpose, since the majority of furnace components are made by the casting process. Standards were cited which give symbols of alloy grades used in technical specifications by the domestic industry. It has been indicated that castings made currently are based on a wider spectrum of the creep-resistant alloy grades than the number of alloys covered by the standards. Alloy grades recommended by the technical literature for individual parts of the furnace equipment were given. The recommendations reflect both the type of the technological process used and the technical tasks performed by individual parts of the furnace equipment. Comments were also made on the role of individual alloying elements in shaping the performance properties of castings