The article presents the results of research on the wear of the cutting tool in the process of high feed milling and plunge milling of the Inconel 718 alloy. A specially designed milling head was used in the study, allowing both of the previously mentioned milling methods to be implemented with a single tool. Ceramic inserts CNGN120712 in versions CS300 and CW100 were used for the research. During the experiment, the values of cutting depth ap [mm], cutting width ae [mm] and feed per edge fz [mm/edge] were changed. The study was conducted under conditions of accelerated wear. The results show the tool life in individual tests using the parameter of the material volume predicted to be removed in the tool life cycle Gmax [cm3], obtained by third degree polynomial approximation.
In the current paper, the effect of tool wear for a constant period of time (360 s) during conventional and ultrasonic assisted machining of Inconel 718 is investigated in terms of cutting forces, temperature, and deviation measurements. For fixed process parameters turning experiments have been performed with and without the application of tangential vibration. Ultrasonic assisted turning (UAT) experiments have been compared with conventional turning (CT). The experimental results reveal that cutting forces and temperature increase linearly in the case of UAT whereas remaining constant in CT for a constant period of time. Besides the tool wear rate in the case of UAT is more than that in the CT.
Hot deformation of metals is a widely used process to produce end products with the desired geometry and required mechanical properties. To properly design the hot forming process, it is necessary to examine how the tested material behaves during hot deformation. Model studies carried out to characterize the behaviour of materials in the hot deformation process can be roughly divided into physical and mathematical simulation techniques. The methodology proposed in this study highlights the possibility of creating rheological models for selected materials using methods of artificial intelligence, such as neuro-fuzzy systems. The main goal of the study is to examine the selected method of artificial intelligence to know how far it is possible to use this method in the development of a predictive model describing the flow of metals in the process of hot deformation. The test material was Inconel 718 alloy, which belongs to the family of austenitic nickel-based superalloys characterized by exceptionally high mechanical properties, physicochemical properties and creep resistance. This alloy is hardly deformable and requires proper understanding of the constitutive behaviour of the material under process conditions to directly enable the optimization of deformability and, indirectly, the development of effective shaping technologies that can guarantee obtaining products with the required microstructure and desired final mechanical properties. To be able to predict the behaviour of the material under non-experimentally tested conditions, a rheological model was developed using the selected method of artificial intelligence, i.e. the Adaptive Neuro-Fuzzy Inference System (ANFIS). The source data used in these studies comes from a material experiment involving compression of the tested alloy on a Gleeble 3800 thermo-mechanical simulator at temperatures of 900, 1000, 1050, 1100, 1150oC with the strain rates of 0.01 - 100 s-1 to a constant true strain value of 0.9. To assess the ability of the developed model to describe the behaviour of the examined alloy during hot deformation, the values of yield stress determined by the developed model (ANFIS) were compared with the results obtained experimentally. The obtained results may also support the numerical modelling of stress-strain curves.
4
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
This research article reports the correlation between microstructure, mechanical properties, and residual stresses of dissimilar weld joints (DWJs) between P92 martensitic steel and 304L austenitic stainless steel (ASS). The groove geometry plays a vital role in DWJs. Thus the effect of groove geometry on mechanical and microstructural properties was also investigated. The V-shape and narrow shape groove profile were implemented for P92/304L SS DWJs. The microstructural characteristic, tensile strength, micro-hardness, Charpy impact toughness and residual stresses were evaluated for both the groove geometry in as-weld (AW) and post-weld heat treatment (PWHT) (760 °C, 2 h) state. Microstructural observations performed using an optical microscope (OM), and scanning electron microscope (SEM) showed that high temperature during the weld thermal cycle leads to the formation of the coarse grain heat-affected zone (CGHAZ), fine grain HAZ (FGHAZ), and inter-critical HAZ (ICHAZ) across the P92 HAZ. The ERNiFeCr-2 (Inconel 718) welding consumable wire (filler rod) of diameter 2.4 mm was used for this investigation. The ERNiFeCr-2 weld fusion zone showed a fully austenitic microstructure with the formation of the secondary phases due to the solidification segregation. The EDS and SEM area mapping results indicated that the secondary phases in the inter-dendritic region contain a higher amount of the Mo and Nb than the matrix region. The ultimate tensile strength (UTS) of the as-weld and PWHT tensile specimen of the P92/304L SS DWJs was 630 and 621 MPa, respectively, for V-groove geometry specimens and 620 and 629 MPa, respectively, for narrow groove geometry specimens. The tensile fracture was experienced at the interface between weld metal and 304L base metal, and the UTS value of DWJs was very close to the UTS of the 304L SS. The abrupt variation in the micro-hardness value of the CGHAZ (456HV0.5), FGHAZ (375HV0.5), and ICHAZ (221HV0.5) was noticed in the as-weld state due to their distinguish microstructure characteristics. After PWHT, the micro-hardness value of the CGHAZ (255HV0.5), FGHAZ (236HV0.5), and ICHAZ (207HV0.5) was below the maximum allowable value of 265HV0.5 for P92 material because of the tempering of the martensite. The Charpy impact test indicated that the ERNiFeCr-2 weld fusion zone has a low toughness value of 33 J (AW) and 25 J (PWHT) for V-groove design and 35 J (AW) and 28 J (PWHT) for narrow groove design than that of the P92 and 304L parent metal. The impact toughness of the ERNiFeCr-2 filler weld was below the minimum requirement of 47 J (EN ISO 3580:2017). The tensile residual stresses were generated in the weld fusion zone due to the volumetric contraction during the solidification. The residual stresses developed in the case of the narrow groove design were less than that for the V-groove design due to the less quantity of weld metal available for volumetric contraction in the case of the narrow groove geometry. From comparing mechanical and microstructural properties obtained for V-groove and narrow groove geometry DWJs, it was found that narrow groove design reduces the overall heat affected zone span, and it requires less welding time and less heat input.
5
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
The nickel-based superalloy Inconel 718 is widely used in aerospace and other fields due to its excellent performance. However, the alloy elements are presented in the form of compounds with high hardness, such as TiC, NbC, MoC, TiN and so on, which lead to complex cutting deformation in machining Inconel 718. In this study, the cutting experiments and the fast tool-drop test were carried out to obtain the chip root. Combining the split Hopkins pressure bar (SHPB) test, a scanning electron microscope (SEM) was used to observe the metallographic micrographs of the specimens and analyzed the plastic dynamic behavior of the material in the cutting area. The soft and hardening mechanism in the dynamic deformation process was described. The stress distribution model of material in the cutting area was proposed and the influence of stress distribution on cutting deformation, side fow and tool wear during the cutting process were also given.
The Inconel 718 alloys, which are primarily temperature resistant, are widely used in aviation, aerospace and nuclear industries. The study on dry cutting processes for this alloy becomes difficult due to its high hardness and low thermal conductivity, wherein, most of the heat transfers due to friction are accumulated over the tool surface. Further, several challenges like increased cutting force, developing high temperature and rapid tool wear are observed during its machining process. To overcome these, the coated tool inserts are used for machining the superalloys. In the present work, the cemented carbide tool is coated with chemical vapor deposition multi-layering Al 2O 3/TiCN under the dry cutting environment. The machining processes are carried out with varying cutting speeds: 65, 81, 95, and 106 m/min, feed rate 0.1 mm/rev, and depth of cut 0.2 mm. The variation in the cutting speeds can attain high temperatures, which may activate built-up-edge development which leads to extensive tool wear. In this context, the detailed chip morphology and its detailed analysis are carried out initially to understand the machining performance. Simultaneously, the surface roughness of the machined surface is studied for a clear understanding of the machining process. The potential tool wear mechanism in terms of abrasion, adhesion, tool chip off, delaminating of coating, flank wear, and crater wear is extensively identified during the processes. From the results, it is observed that the machining process at 81 m/min corresponds to a better machining process in terms of lesser cutting force, lower cutting temperature, better surface finish, and reduced tool wear than the other machining processes.
The properties of Iconel 718 determine its application for parts operating in extremely tough conditions. The difficulties when machining nickel-based superalloys allowed in recent years for researching other machining methods. One of the proposed methods is Wire Electrical Discharge Machining (WEDM). It becomes possible to minimize or eliminate such problems associated with electrical discharge machining as microcracks, forming of a white layer, or high surface roughness. One way to avoid these issues is to apply finishing machining. The literature indicates that the peak current is the main parameter responsible for shaping the machined surface in finishing WEDM. Furthermore, few works focus on the electrode’s infeed, in particular there are not many papers regarding the influence of the infeed on the machined surface parameters. Therefore, the paper aims to investigate on the influence of the peak current and infeed during finishing WEDM on the surface properties of Inconel 718. The paper presents measurements of selected surface topography parameters and Abbot Firestone curves (AFC). The presented plots allowed to determine the ranges of the process parameters for which the lowest surface roughness values were achieved. Cross-sections were performed to measure the thickness of a white layer. Nanohardness HV0,01 measured by Berkovich tip was recorded to determine the size of a heat affected zone (HAZ). The correlation between the peak current Ic and the infeed z regarding the machined surface quality was presented.
Selective laser melting (SLM) falls into the category of additive manufacturing technologies that are being increasingly used in the aerospace industry. This study presents the results of the examination of the microstructure and mechanical properties of selective laser melted Inconel 718. The tests were carried out for samples of different geometry (thickness, shape). The investigation showed the effect of the specimen’s size and the printing direction on the microstructure and mechanical properties. In the microstructural investigation, light and scanning electron microscopes were used. The microstructure investigation included measurements of the grain size and the carbides’ content. In order to estimate porosity computer tomography was used. Tensile tests were carried out at room temperature. The results showed differences in mechanical and microstructural properties of different size specimens.
The paper deals with analysis of samples made of Inconel 718 nickel superalloy, produced using direct metal laser sintering (DMLS), known as “sintering”, and precision casting technologies. The theoretical part is focused on the characteristics of producing samples of the nickel superalloy by modern additive methods (those for processing metallic materials) and by the conventional technology of precision casting. The practical part involves the investigation of the mechanical properties and texture of the surfaces of the tested samples. A significant part of this study is devoted to analysis of fracture surfaces and EDX experimental testing of TEM lamella by using of electron microscopy methods. The conclusions of this paper include a discussion, evaluation and explanation of both technologies applied on tested samples. Finally, the main benefits of using modern additive technologies in the design and production of heat-resistant components of turbochargers are discussed.
Inconel 718 is one of the modern materials widely used in the aviation and space industry, due to their excellent mechanical and chemical properties at elevated temperatures. These parts work in difficult conditions and they are required to be characterized by good accuracy and high quality surface finish to ensure greater durability and fatigue strength. Conventional machining of these materials is difficult and ineffective due to low thermal conductivity of the alloy. Electrical discharge machining (EDM) is often used to machine materials regardless of their mechanical and physical properties. In this process material is removed from the workpiece through series of electric discharges occurring in the sparking gap between a tool electrode and the workpiece. The physics of removing material from the workpiece is completely different from other traditional machining methods, and its effects determine the functional properties of the surface layer. The purpose of the experimental research was to investigate the influence of machining parameters on surface texture of Inconel 718 after electrical discharge machining assisted with ultrasonic vibration of the tool electrode (EDM+US). The study was carried out with a design experimental methodology. Input parameters were discharged current I and pulse duration ton. Roughness parameters Sa, St, Sz were designated for each machined surface.
PL
Inconel 718 jest jednym ze współczesnych materiałów szeroko stosowanych w przemyśle lotniczym i kosmicznym, ze względu na jego doskonałe właściwości mechaniczne i chemiczne w podwyższonych temperaturach. Elementy te pracują w trudnych warunkach i muszą charakteryzować się dobrą dokładnością i wysoką jakością wykończenia powierzchni, aby zapewnić większą trwałość i wytrzymałość zmęczeniową. Ze względu na niskie przewodnictwo cieplne konwencjonalna obróbka stopów Inconel jest bardzo trudna i mało skuteczna. Obróbka elektroerozyjna (EDM) jest często wykorzystywana do obróbki materiałów trudnoobrabialnych, niezależnie od ich właściwości mechanicznych i fizycznych. W procesie tym materiał jest usuwany z obrabianego przedmiotu poprzez wyładowania elektryczne, które zachodzą w szczelinie pomiędzy elektrodą roboczą a przedmiotem obrabianym. Fizyka usuwania materiału z przedmiotu obrabianego jest całkowicie odmienna od innych tradycyjnych metod obróbkowych, a jej efekty determinują własności użytkowe warstwy wierzchniej. Celem badań eksperymentalnych było określenie wpływu parametrów obróbki elektroerozyjnej wspomaganej drganiem ultradźwiękowym elektrody roboczej (EDM+US) na strukturę geometryczną powierzchni Inconelu 718. Badania przeprowadzono według metodyki eksperymentu planowanego. Parametrami wejściowymi były: natężenie prądu I i czas impulsu ton. Dla każdej obrobionej powierzchni próbki wyznaczono przestrzenne parametry chropowatości: Sa, St, Sz.
Requirements currently imposed on machine elements are constantly growing. It requires to develop new, advanced machining processes. One of the commonly used finishing process is grinding. The article presents the results of the exploratory research in the process of surface grinding with abrasive multigrain wheels of samples made of Inconel 718. The influence of input parameters was investigated: cutting speed Vc, transverse feed speed Fp, longitudinal feed speed Fw, on roughness parameters (Sa) and the bearing capacity curve. Based on the conducted research, statistical models of the grinding process were elaborated, which allow to select the most favorable processing parameters depending on the required quality of the surface texture.
PL
Wymagania obecnie nakładane na elementy maszyn stale rosną. Powoduje to konieczność opracowania nowych, zaawansowanych procesów obróbki. Jednym z powszechnie stosowanych procesów wykańczających jest szlifowanie. W artykule przedstawiono wyniki badań rozpoznawczych procesu szlifowania powierzchni próbek wykonanych z Inconelu 718, ściernicami wielogranulacyjnymi. Zbadano wpływ parametrów wejściowych: prędkości skrawania Ve, prędkości posuwu poprzecznego Fp, prędkości posuwu wzdłużnego Fw, na parametr chropowatości (Sa) i krzywą nośności. Na podstawie przeprowadzonych badań opracowano modele statystyczne procesu szlifowania, które pozwalają wybrać najkorzystniejsze parametry obróbki w zależności od wymaganej jakości wykończenia powierzchni.
12
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
This paper applies to the tests of the machining of a part made of supper alloy – nickel alloy – Inconel 718, using a monolithic carbide cutter. The paper includes a different versions of cutting methods with variable cutting parameters and machining strategies. The used sustainable machining process allowed to obtain control over the tool wear.
PL
Artykuł dotyczy badań obróbki ubytkowej części wykonanej ze stopu na osnowie z niklu – Inconel 718, z zastosowaniem monolitycznego frezu z węglików spiekanych. Przedstawiono różne metody obróbki części przy zmiennych parametrach skrawania oraz strategiach. Zastosowano zrównoważony proces obróbki, który pozwolił uzyskać kontrolę nad zużyciem narzędzi skrawających.
13
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
Research concerns the evaluation of the cutting insert condition on the microstructure of the surface layer after longitudinal turning of Inconel 718 alloy using carbide inserts. Value of the VBC wear index after dry machining with variable feed f and depth of cut ap was evaluated. White layer was observed up to 2,5 μm.
PL
Badano wpływ stanu ostrza na mikrostrukturę technologicznej warstwy wierzchniej po toczeniu wzdłużnym stopu Inconel 718 ostrzami węglikowymi. Oceniano wartość wskaźnika zużycia VBC po toczeniu na sucho ze zmiennymi parametrami posuwu f oraz głębokości skrawania ap. Zaobserwowano obecność białej warstwy na głębokości do 2,5 μm.
This work deals with the problem of X-ray stress determination on the samples dedicated to fatigue tests. A number of research studies point out the fact that the processing of hard, difficult to machine materials like nickel superalloys, reveals more than one trend of residual stress versus working parameters of behaviour (Lavella and Berruti, 2010). Many papers have shown that the residual stresses are dependent on a combination of a number of factors. When the above is taken into account simultaneously with the requirements of the internal General Electric specification for the fatigue tests samples preparation (Metallic test specimen preparation, low stress, 2017) the problem of turning and grinding parameters gathers significance. It is well known that the quality of the surface layer, produced during machining, is of vital importance for the fatigue life specially for the components of aircraft produced form nickel superalloys e.g. Inconel 718 (Kortabarri et al., 2011). That is why the surface layer’s properties are described in detail by the standards. The aim of the work is to determine one of the most influential features from the point of view of fatigue life, i.e. the stress state on the surface layer with one non-destructive method - the diffraction analysis.
In this study, the coefficients of friction for three series of welded nickel alloy joints, subjected to different heat treatments (lack of heat treatment, solution heat treatment, precipitation hardening), were determined. Heat treatment of the prepared samples was aimed at eliminating the structural and stress gradient, because the electron beam welding technique is dedicated for constructions with very high quality and strength requirements. Given the nature of the electron beam process, the authors are aware that the obtained weld’s structures are characterized by different properties from parent materials, and also from structures melted under equilibrium conditions. The scientific aim of the presented work is to determine the influence of heat treatment on the microstructure, mechanical properties, and performance of dissimilar joints of nickel alloys Inconel 625 and Inconel 718. In order to determine the coefficient of friction for samples, the scratch test method was used. As a result of the research, it was proved that subjecting the welds to the precipitation hardening has a significant effect on abrasion resistance.
PL
Wyznaczono współczynniki tarcia dla trzech serii próbek poddanych odmiennym procesom obróbki cieplnej (brak obróbki cieplnej, przesycanie, utwardzanie wydzieleniowe). Obróbka cieplna przygotowanych próbek miała na celu zlikwidowanie gradientu strukturalnego i naprężeniowego, ponieważ spawanie wiązką elektronów dedykowane jest dla urządzeń o bardzo wysokich wymaganiach jakościowych i wytrzymałościowych. Biorąc pod uwagę charakter procesu spawania wiązką, autorzy mają świadomość, iż uzyskane struktury będą cechowały się zdecydowanie odmiennymi własnościami od materiału rodzimego, ale również i od struktur przetopionych w warunkach bliskich warunkom równowagowym. Celem naukowym pracy jest określenie wpływu obróbki cieplnej na mikrostrukturę, własności mechaniczne i użytkowe różnoimiennych połączeń stopów niklu Inconel 625 oraz Inconel 718. W celu wyznaczenia współczynników tarcia dla próbek zastosowano metodę zarysowania scratch test. W wyniku przeprowadzonych badań dowiedziono, że poddanie spoin procesowi utwardzania wydzieleniowego ma znaczący wpływ na odporność na ścieranie.
The development of industry is determined by the use of modern materials in the production of parts and equipment. In recent years, there has been a significant increase in the use of nickel-based superalloys in the aerospace, energy and space industries. Due to their properties, these alloys belong to the group of materials hard-to-machine with conventional methods. One of the non-conventional manufacturing technologies that allow the machining of geometrically complex parts from nickel-based superalloys is electrical discharge machining. The article presents the results of experimental investigations of the impact of EDM parameters on the surfaces roughness and the material removal rate. Based on the results of empirical research, mathematical models of the EDM process were developed, which allow for the selection of the most favourable processing parameters for the expected values of the surface roughness Sa and the material removal rate.
Prezentowane badania dotyczą toczenia stopu Inconel 718 ostrzami z CBN w warunkach skrawania konwencjonalnego oraz wspomaganego laserowo. Przedstawiono wpływ prędkości skrawania na wybrane wartości parametrów chropowatości powierzchni. Dokonano optymalizacji parametrów technologicznych ze względu na minimalizację wartości wyjściowych.
EN
Presented research is focused on turning of Inconel 718 with CBN cutting inserts under conventional and laser assisted turning conditions. The influence of cutting speed on the values of selected parameters of surface roughness was shown. The optimization of technological parameters was carried out due to the minimization of the values of output parameters.
W artykule przedstawiono wyniki badań momentu skrawania i chropowatości powierzchni w procesie frezowania czołowego stopu niklu Inconel 718. W eksperymencie wykorzystano narzędzia monolityczne o średnicy d = 12 mm, wykonane z ceramiki SIALON. Badania przeprowadzono przy zmiennych parametrach technologicznych: ap = 0,8-1,2 mm, vc = 400-898 m/min, fz = 0,07-0,16 mm/ostrze. Zauważono, że wzrost posuwu na ostrze fz i głębokości skrawania ap powoduje większe wartości momentu skrawania Mc. W zakresie vc = 400-732 m/min następuje spadek wartości momentu skrawania Mc. Parametry chropowatości powierzchni również zależą od warunków obróbki.
EN
This paper presents the results of an investigation of the cutting torque and surface roughness in the face milling of nickel-based alloy Inconel 718. In the experimental tests monolithic tools with a diameter of d = 12 mm made of SIALON ceramics were used. The tests were conducted at variable technological parameters: ap = 0.8-2 mm; vc = 400-893 m/min; fz = 0.07-0.16 mm/per tooth. It has been found that increasing the feed per tooth fz and the depth of cut ap resulted in a higher cutting torque. In the range of vc = 400-732 m/min the decrease of cutting torque Mc was observed. Surface roughness parameters also depended on machining conditions.
19
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
Wymagania jakościowe dotyczące wytwarzania odpowiedzialnych części w przemyśle lotniczym często eliminowały zastosowanie obróbki elektroerozyjnej w produkcji tych elementów. Stosowane dotychczas kształtowanie metodami skrawania trudno obrabialnych stopów niklu i tytanu wiąże się z wysokimi kosztami. Stąd też takie zalety obróbki elektroerozyjnej jak możliwość obróbki materiałów przewodzących bez względu na ich twardość oraz elastyczność technologii wycinania elektroerozyjnego dowolnych kształtów umożliwiają obróbkę części silników, m.in. w przemyśle lotniczym lub energetycznym. W artykule przedstawiono badania zjawisk wpływu parametrów obróbki WEDM (Wire Electrical Discharge Machining) na wybrane parametry struktury geometrycznej powierzchni (SGP) stopu lotniczego Inconel 718.
EN
For a long time industry requirements for demanding jet engine components manufacturing did not allow to use electrical discharge machining to manufacture these components. However, shaping difficult-to-cut nickel and titanium alloys by cutting methods is associated with high costs. The advantages of electrical discharge machining, such as the possibility to machine conductive materials regardless of their hardness and high production flexibility, allow to machine demanding engine parts in the aerospace or energy industry. The paper presents the study of WEDM (Wire Electrical Discharge Machining) parameters and their influence on the selected parameters of the Inconel 718 surface texture parameters.
20
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
W pracy przedstawiono wpływ spawania metodą GTAW i laserem bez dodatku spoiwa, cienkich blach ze stopu Inconel 718 na żarowytrzymałość ich złączy. Technologiczne próby żarowytrzymałości próbek ze złączami spawanymi prowadzono przy użyciu pełzarki w stałej temperaturze wynoszącej 860±2 °C i przy stałym naprężeniu σ = 150 MPa. Badania wykazały, że złącza spawane tych blach wykonane laserem zarówno w stanie ich dostawy, jak i po obróbce cieplnej posiadają o ok. 60÷80% większą żarowytrzymałość niż złącza wykonane metodą GTAW.
EN
The paper presents the influence of GTAW welding and laser without the addition of binders, thin sheets of Inconel 718 on the creep resistance of the connectors. Process sample creep resistance specimens of fused-fiber couplers were carried out using creep testing machine using a constant temperature of 860±2 °C and a constant stress o = 150 MPa. The tests have shown that welded joints of these sheets made with a laser, both in the state of their delivery and after heat treatment, have about 60-80% hiqher heat resistance than joints made using the GTAW method.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.