Grinding force directly affects the grinding equipment performance, the grinding tool wear, and the machined surface quality, and it is an important grinding performance indicator. In this paper, a tangential force prediction model is established for robot abrasive belt grinding (RABG) of nickel-based superalloy. According to the shape characteristics of grits and the interaction mechanism between grits and workpiece, the tangential components of cutting force and frictional force on the grits are determined. On this basis, the tangential force prediction model is established by the grit protrusion height distribution and the elastic contact theory. In addition, according to the wear characteristics of the structured abrasive belt, the expression of grit distribution density (i.e. the number of grits per unit area) is obtained and applied to the tangential force model. The force model is evaluated by the verification experiment, and the results show that it has good prediction ability. At the same time, this paper discusses the influence of grinding parameters on tangential force, and reveals the material removal characteristics of RABG of nickel-based superalloy based on the analysis of the tangential force and the morphology characteristics of grinding surfaces and chips.
2
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
The preparation of nickel-based superalloy tubes by rotary tube piercing (RTP) process is still difficult due to the Mannesmann effect (central cracking phenomenon) has not been clarified. The combinations of numerical analysis and experiment verifications method were adopted in the study. The critical parameters for central cracking were determined by experiments. It was found that the evolution process of central cracking for nickel-based superalloy includes voids nucleation, growth and aggregation. Based on the obtained critical parameters, the evolutions of stress, strain, strain rate, temperature and damage were discussed by numerical simulation. By comparing the experiment results and simulation results, the Normalized Cockcroft and Latham (NCL) model was determined as the most suitable model. Considering the influences of temperature and strain rate on the damage threshold, the NCL model of Inconel 718 alloy was established by high-temperature tensile test. Based on the above results, it is found that the maximum shear stress promotes the plastic deformation, which provides necessary conditions for the generation of defects, and the maximum principal stress induces the generation of voids and expansion of micro-cracks, which directly leads to the central cracking. The essence of central cracking is ductile fracture under tensile stress.
Opracowano warunki wytwarzania warstw diamentopodobnych na stopie niklu IN 718 z zastosowaniem aparatury PACVD. Prowadzono procesy w temperaturze 550°C i 600°C przez 6 godzin. Jako gazów reakcyjnych użyto metanu i wodoru. Proporcja metanu do wodoru wynosiła 1 do 200. Wykonano analizy składu fazowego powłok, badania twardości oraz przyczepności. Otrzymane powłoki diamentopodobne mają dobrą przyczepność do podłoża oraz dużą twardość (ok. 1500 HV).
EN
The aim of the study was development of the conditions for manufacturing diamond-like carbon (DLC) coatings on the IN 718 nickel based alloy using the PACVD method. The CVD processes were carried out at the temperature of 550 and 600°C during 6 hours. Methane and hydrogen in the proportion of 1:200 were used as the reaction gases. The phase composition, hardness and adhesion of the coatings were examined. The hardness of the DLC coatings was found to be about 1500 HV and they showed good adhesion to the substrate.
This paper provides an analysis of experimental research and results of investment casting process. Temperature field in a ceramic mold is one of the problems during numerical simulation. Reducing the costs of production in precision casting involves the reduction of scraps, which is one of the fundamental problems of the foundry industry. Reducing these costs is associated with optimization of precision casting technology of aircraft engines critical parts, including control of the solidification front in thin-walled castings of nickel super alloys cast in a vacuum. It is achieved by changing the geometrical characteristics of the ceramic mold. The results of the tests were used to optimize the industrial production of aircraft components in Precision Foundry of WSK Rzeszów. Temperature distribution gained in the conducted tests allowed verification and optimization of computer simulations.
Celem pracy było opracowanie warunków procesu nisko i wysokoaktywnego aluminiowania nadstopu niklu René77 z zastosowaniem metody chemicznego osadzania z fazy gazowej. Wytworzono dyfuzyjne warstwy żaroodporne na osnowie aluminidków niklu. Określono wpływ czasu procesu prowadzonego w temperaturze 1050°C na głębokość wytworzonych warstw. Celem zwiększenia grubości warstwy ochronnej zastosowano dodatkowe wyżarzanie po procesie wysokoaktywnym. Wykonano badania odporności na utlenianie wytworzonych warstw oraz analizę składu fazowego warstwy. Stwierdzono, że wytworzone warstwy aluminidkowe zwiększają odporność na utlenianie podłoża – stopu René 77.
EN
The aim of the study was development of aluminizing process of the René 77 superalloy by the CVD method. Heat resistant diffusion layers based on nickel aluminides were produced. The influence of time of CVD process carried out at 1050°C on the thickness of the coatings was determined. Additional annealing was also applied after high activity process to increase the thickness of the protective coating. Phase composition of the aluminide coatings was examined. On the basis of the oxidation tests results it was found that applied coatings improved oxidation resistance of René 77 superalloy.
Prowadzono badania oceny wpływu żaroodpornej warstwy aluminidkowej uzyskanej w niskoaktywnym procesie aluminiowania CVD na żarowytrzymałość nadstopu niklu Rene77. Opracowano warunki procesu aluminiowania i wytworzono warstwę aluminidkową o głębokości ok. 20 um i 35 um. Wykonano badania odporności warstwy na utlenianie izotermiczne w temperaturze 982°C (1800 F), czas wygrzewania - 1000 h. Prowadzono próby przyspieszonego pełzania w temperaturze 982°C (1800 F) przy naprężeniu 151,7 MPa (przed i po aluminiowaniu). Wykonano analizy składu chemicznego i fazowego warstwy na powierzchni po procesie aluminiowania. Stwierdzono, że wytworzona warstwa zwiększa odporność na utlenienie podłoża - Rene77 przy zachowaniu jego właściwości mechanicznych.
EN
The influence of aluminide coating developed on Rene77 superalloy in low activity CVD process on oxidation resistance and mechanical properties of the alloy was examined. After selection of process parameters aluminide coatings with the depth of 20 and 35 um were formed. The oxidation tests were carried out at 982°C (1800 F) for 1000 h. Stress rupture tests at 982°C (1800 F) were accomplished at the stress level of 151.7 MPa for the alloy before and after aluminizing. Chemical and phase composition on the surface of the aluminide coating was examined. It was found that applied coating improved oxidation resistance of Rene77 superalloy without deterioration of mechanical properties.
The influence of the CVD aluminizing of the Rene 77 superalloy carried out before and after solution treatment on the microstructure of the aluminide coating and alloy properties was studied. Depth of the diffusion type aluminide layer obtained in aluminizing process (1050°C/8 h) was about 35 um. In both cases ageing at 760°C for 4 hours was conducted in the last stage of treatment. Chemical composition and microstructure of aluminide coatings were characterized. Cyclic oxidation tests at 1100°C were performed in total time of 500 h and the creep rupture tests were carried out at 982°C for two stress levels: 124.0 and 151.7 MPa. It was found that the alloy aluminized after solution treatment exhibits better resistance to high temperature oxidation and higher creep properties comparing to the alloy aluminized before heat treatment.
PL
Prowadzono badania wpływu aluminiowania metodą CVD stopu Rene 77, wykonanego przed i po procesie przesycania, na mikrostrukturę warstwy aluminidkowej i właściwości stopu. Przyjęto schemat procesu aluminiowania i wytworzono warstwę aluminidkową o głębokości 35 um. Starzenie przeprowadzono po zakończeniu obróbki cieplno-chemicznej dla obydwu wariantów. Scharakteryzowano skład chemiczny oraz mikrostrukturę warstw aluminidkowych. Dla obu wykonanych wariantów obróbki cieplno-chemicznej przeprowadzono próbę utleniania cyklicznego w temperaturze 1100°C w łącznym czasie 500 h oraz próbę przyspieszonego pełzania w temperaturze 982°C dla dwóch poziomów naprężenia: 124,0 MPa i 151,7 MPa. Stwierdzono, że przeprowadzenie procesu aluminiowania po procesie przesycania pozwala na uzyskanie większej odporności na utlenianie stopu oraz lepszych właściwości w warunkach pełzania w porównaniu ze stopem aluminiowanym przed przesycaniem.
8
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
The purpose of this study was to investigate typical casting defects occurring in investment cast turbofan engine parts made of IN713 C superalloy. SEM and EDS examinations were used to reveal that dross and non-metallic inclusions of a shell mould and crucible material are the most frequently occurring defects. A hypothesis is put forward with regard to the mechanisms of dross formation. EBSD studies were also carried out to reveal grain structure of the elements in question.
W pracy omówiono wpływ aluminiowych warstw żaroodpornych stosowanych jako pokrycia ochronne łopatek lotniczych silników turbinowych na trwałość żarowytrzymałych stopów niklu w warunkach oddziaływania obciążeń mechanicznych i cieplnych. Analizowano warunki powstawania i wzrostu pęknięć w aluminiowych warstwach ochronnych z uwzględnieniem cech ich mikrostruktury w warunkach zmęczenia wysokocyklowego, niskocyklowego, a także zmęczenia cieplnego.
EN
The paper deals with the influence of aluminium heat-resisting coatings used as protective coatings vor vanes in aircraft turbine engines upon the lifetime of heat-resisting nickel based alloys when thermal and mechanical loadings are being applied. The conditions of initiation and growth of cracks in aluminium protective coating have been analysed with particular attention being paid to their microstructural features in high-cycle, low-cycle and thermal fatigue conditions.
W pracy przedstawiono analizę wpływu struktury stopów na osnowie fazy międzymetalicznej Ni3Al na ich odporność na korozję wżerową w wodnym roztworze NaCl. Próby korozyjne przeprowadzono metodą cyklicznej polaryzacji anodowej w wersji potencjodynamicznej oraz potencjostatycznej. Badano stopy na osnowie fazy międzymetalicznej Ni3Al z dodatkami stopowymi boru i cyrkonu (stop nr 1) lub boru, chromu, molibdenu i cyrkonu (stop nr 2).
EN
The influence of Ni3Al-based intermetallic alloys structure on their pitting corrosion resistance in sodium chloride aqueous solution was discussed in this paper. Corrosion tests were done by cyclic anodic polarisation method both in potentiodynamic and potentiostatic version. Ni3Al intermetallic phase-based alloys with additions of boron and zirconium (alloy no. 1) or boron, zirconium, chromium and molybdenum (alloy no. 2) were investigated.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.