Research on Mechanical Properties of Thin Sheets Blanks Made of Creep-Resisting Nickel Superalloys

2013 ◽  
Vol 212 ◽  
pp. 259-262
Author(s):  
Monika Hyrcza-Michalska
Keyword(s):  
Mechanical Properties ◽  
Inconel 718 ◽  
Nickel Alloys ◽  
Thin Sheet ◽  
High Strength ◽  
Inconel 625 ◽  
Thin Sheets ◽  
Inconel 718 Alloy ◽  
Mechanical Working ◽  
Inconel Alloys

Mechanical working manufacturing methods of nickel alloys used conventionally strips and blanks need to solve many problems concerning high strength material forming which is characteristic limited plasticity. The production pressed elements of vehicle constructions and aircraft engine elements requires the high quality drawpieces since these are essential for safety. They are also the main structural components. Conventional methods of mechanical working such as pressing can be used in quantity production of the above mentioned elements and their production can also be cost-effective. Forming nickel alloys generates a lot of technological wastes resulting from back-springing effects determining the most appropriate pressure in the process of pressing. Failure holes in the process of bulging as well as cracking of drawpieces in the process of deep drawing. The heterogeneous mechanical properties distribution on thin sheet blanks made of Inconel alloy, which is different than material quality certificate shows, produces also a lot of manufacturing problems. These problems are usually solved by production engineers in the following way: dividing the production of ready drawpieces into a bigger number of simple blank profiling operations, shallow pressing, using a rubber punch for pressing or hydroforming. Complex drawpieces shapes are quite often made of several parts which are next welded. In the case of presented tube a tubular diffuser made of Inconel 718 alloy blank and cone made of Inconel 625. However the process of forming high strength materials like nickel alloys requires the application bigger forming forces than in the same kind of conventional formable steel processes. Tools get jammed quite often in the process and high force presses of 10 MN or more need to be used so is very expensive. The aspect of cold mechanical forming discussed materials has been a particular interest. The researches based on precise evaluation mechanical properties and technological plasticity of the selected materials in basic mechanical and technological tests as well as in FEM numerical simulation (finite elements method). The material models applied to simulation contain the pointed out experimentally the mechanical characteristics of Inconel alloys. The thin sheets blanks made of 0,9 mm thick Inconel 718 alloy and 0,45 mm thick Inconel 625 alloy blanks have been examined. The possibilities of using numerical simulations for solving the problems of selecting or modifying the pressing technology and hydroforming that type materials as well as forecasting the results of forming processes have been also presented. The evaluation of drawability of thin sheets blanks made of Inconel 718 and 625 alloys has also been discussed in the paper.

Evaluation of the Performance of Inconel 718 Fasteners Subjected to Cathodic Protection Systems in Offshore and Subsea Applications

2011 ◽  
Author(s):  
Fabio Pires ◽  
Richard Clements ◽  
Fabio Santos ◽  
Judimar Clevelario ◽  
Terry Sheldrake
Keyword(s):  
Mechanical Properties ◽  
Cathodic Protection ◽  
Inconel 718 ◽  
Nickel Alloys ◽  
High Strength ◽  
Maximum Hardness ◽  
Inconel 718 Alloy ◽  
Protection Systems ◽  
Impressed Current ◽  
Current Systems

Fasteners manufactured with Inconel 718 alloy are being widely used in offshore and subsea applications due to the material’s high strength, when compared to other nickel alloys, and its inherent corrosion resistance. However, concerns have been raised over its utilization in applications where cathodic protection or impressed current systems are in place. These concerns relate to the susceptibility to hydrogen embrittlement that Inconel 718 alloy may present depending on its processing, microstructure, hardness and actuating stresses. Over the last few years, much has been discussed on the suitability of the alloy for subsea applications. The development of special thermal cycles for the ageing of the alloy has been necessary to provide a consistent material with a maximum hardness of 35 HRc, and a microstructure free of detrimental phases without jeopardizing the overall mechanical properties of the alloy. Wellstream has developed a test programme focused on the assessment of Inconel 718 behavior when subjected to cathodic protection systems. Through this programme, it was possible to demonstrate the suitability of Inconel 718 alloy in subsea applications when the resulting microstructure and hardness are properly controlled, and bolt loading is within normal working limits.

scholarly journals Studying the effect of heat treatment modes on corrosion resistance of welded joints

2021 ◽  
pp. 23
Author(s):  
Nataliya Kalinina ◽  
Vasiliy Kalinin ◽  
Ivannа Serzhenko
Keyword(s):  
Mechanical Properties ◽  
Heat Resistance ◽  
Inconel 718 ◽  
Gas Turbines ◽  
Nickel Alloys ◽  
Oil And Gas ◽  
Inconel 718 Alloy ◽  
Heat Resistant ◽  
Complex Chemical Composition ◽  
Metallurgical Furnaces

Welded joints with corrosion-resistant steels and heat-resistant alloys, which require different modes of heat treatment to achieve the level of mechanical properties specified in the design documentation, are used for the manufacture of parts and components of the turbo-pumping unit (TPU) and liquid rocket engine. Heat-resistant alloys are a large group of alloys on iron, nickel and cobalt bases with the addition of chromium and other alloying elements (C, V, Mo, Nb, W, Ti, Al, B, etc.), whose main feature is to maintain high strength at high and cryogenic temperatures. Heat-resistant alloys are used in the manufacture of many parts of gas turbines in rocketry and jet aircraft, stationary gas turbines, the pumping of oil and gas, hydrogenation of fuel in metallurgical furnaces and many other installations. For the doping of nickel chromium γ-solid solution, several elements are used, which differently influence the increase of heat resistance and processability. Along with the main reinforcing elements (Ti, Al), refractory elements (W, Mo, Nb) are introduced into the alloy, which increase the thermal stability of the solid solution. Heat resistant alloys are based on cobalt. Cobalt has a positive effect on the heat-resistant properties of alloys. The introduction of chromium in cobalt increases its heat resistance and hardness. In addition to chromium, alloys containing cobalt include additives of other alloying elements that improve their various properties at high temperatures. A characteristic feature of these alloys is that they have relatively low heat resistance characteristics at moderate temperatures, which, however, change a little with the temperature up to 900 ° C and therefore become quite high compared to the characteristics of other heat-resistant alloys. A significant drawback of these alloys is their high cost due to the costly cobalt. Nickel-based heat-resistant alloys typically have a complex chemical composition. It includes 12–13 components, carefully balanced to obtain the required properties. The content of impurities such as silicon (Si), phosphorus (P), sulfur (S), oxygen (O) and nitrogen (N) is also controlled. The content of elements such as selenium (Se), tellurium (Te), lead (Pb) and bismuth (Bi) should be negligible, which is provided by the selection of charge materials with low content of these elements, because it is not possible to get rid of them during melting. These alloys typically contain 10–12 % chromium (Cr), up to 8% aluminum (Al) and titanium (Ti), 5–10 % cobalt (Co), as well as small amounts of boron (B), zirconium (Zr) and carbon (C). Molybdenum (Mo), tungsten (W), niobium (Nb), tantalum (Ta) and hafnium (Hf) are sometimes added. Heat-resistant alloys are used for the production of many parts of gas turbines in rocketry and jet aircrafts, stationary gas turbines, for pumping oil and gas products, for hydrogenation of fuel in metallurgical furnaces and in many other installations. Nickel-based heat-resistant alloys are also cryogenic, i.e., they are capable of operating and retaining mechanical properties at very low temperatures (–100 °C to –269 °C). Such alloys are chromium-nickel alloys having an austenitic structure. Not only do they have good mechanical properties that do not change over a large temperature range (–200 °C to 900 °C), they can also work in corrosive environments. Nickel-based heat-resistant alloys typically have a complex chemical composition. It includes 12–13 components, carefully balanced to obtain the required properties. Welded and combined workpieces are made of separate components that are interconnected by various welding methods. Welded and combined blanks greatly simplify the creation of complex configuration designs. Improper workpiece design or incorrect welding technology can cause defects (grooves, porosity, internal stresses) that are difficult to correct by machining. Given that finding replacements with multiple materials, working them out in production, and investigating interconnectivity during thermal forces in a product can take considerable time and money, it would be best to replace one alloy. Unifying the material used would allow the structure to work as a whole, which would increase the manufacturability of the products. After examining the different replacement options, inconel 718 was selected for the study. Studies of welded specimens of inconel 718 alloy-stainless steel for resistance to the ICC have shown that it is not appropriate to use  welded  inconel  718 for the impeller, it is advisable to use material that would ensure uninterrupted operation in a corrosive environment at cryogenic temperatures. Based on the working conditions of the parts, it is most expedient to make it from heat-resistant chromium-nickel alloys, namely, from float inconel 718 which meets the necessary strength characteristics. The recommended soldering mode is heating up to 950 ± 10 oC, holding for 30 minutes from the moment of loading into the oven, cooling to 3000C with the oven, further in the air, since it has less influence on the corrosion resistance of steels in stainless steel joints. Quality control of inconel 718 alloy by GOST methods similar to that used for the control of X67MBHT type alloys showed the results similar to those obtained by the ASTM and AMS control methods.

scholarly journals The Precipitation Processes and Mechanical Properties of Aged Inconel 718 Alloy After Annealing

2017 ◽  
Vol 62 (3) ◽  
pp. 1695-1702 ◽  
Author(s):  
P. Maj ◽  
B. Adamczyk-Cieslak ◽  
M. Slesik ◽  
J. Mizera ◽  
T. Pieja ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Inconel 718 ◽  
Aging Process ◽  
High Strength ◽  
Inconel 718 Alloy ◽  
Transmission Microscopy ◽  
Nickel Iron ◽  
Temperature Range ◽  
Hardness Tests ◽  
Strength And Ductility

AbstractInconel 718 is a precipitation hardenable nickel-iron based superalloy. It has exceptionally high strength and ductility compared to other metallic materials. This is due to intense precipitation of the γ’ and γ” strengthening phases in the temperature range 650-850°C. The main purpose of the authors was to analyze the aging process in Inconel 718 obtained in accordance with AMS 5596, and its effect on the mechanical properties. Tensile and hardness tests were used to evaluate the mechanical properties, in the initial aging process and after reheating, as a function of temperature and time respectively in the ranges 650°-900°C and 5-480 min. In addition, to link the mechanical properties with the microstructure transmission microscopy observations were carried out in selected specimens. As a result, factors influencing the microstructure changes at various stages of strengthening were observed. The authors found that the γ’’ phase nucleates mostly homogenously in the temperature range 650-750°C, causing the greatest increase in strength. On the other hand, the γ’ and δ phases are formed heterogeneously at 850°C or after longer annealing in 800°C, which may weaken the material.

Precipitation of γ″ in Inconel 718 alloy from microstructure to mechanical properties.

Materialia ◽  
2021 ◽  
pp. 101187
Author(s):  
Alexandre Balan ◽  
Michel Perez ◽  
Thibaut Chaise ◽  
Sophie Cazottes ◽  
Didier Bardel ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Inconel 718 ◽  
Inconel 718 Alloy

scholarly journals Anisotropy Study of Inconel 718 alloy at Sub-Zero temperatures

2020 ◽  
Vol 184 ◽  
pp. 01004
Author(s):  
L Jayahari ◽  
K Nagachary ◽  
Chandra Ch Sharath ◽  
SM Hussaini
Keyword(s):  
Mechanical Properties ◽  
Strain Hardening ◽  
Inconel 718 ◽  
Anisotropy Parameter ◽  
Tensile Tests ◽  
Strain Hardening Exponent ◽  
Inconel 718 Alloy ◽  
Normal Anisotropy ◽  
Axial Tensile ◽  
Forming Characteristics

There is an increase in demand for new alloys in aerospace, power generation and nuclear industries. Nickel Based super alloys are known for having distinctive properties which are best suitable for these industries. In this study Nickel based super alloy Inconel 718, is used. Over the many years of intense research and development, these alloys have seen considerable evolution in their properties and efficiency. Behaviour of materials and its forming characteristics can be precisely analysed by determining anisotropic behaviour and mechanical properties. In the present study, tried to analyse the mechanical properties of Inconel 718 like yield strength (Ys), ultimate tensile strength (UTS), strain hardening exponent (n) and strain hardening coefficient (k). Uni-axial tensile tests were conducted on specimens with various parameters such as orientations, temperature and Strain rate. Anisotropy of Inconel 718 alloy was measured based on measurable parameters. The normal anisotropy parameter (f) and planer anisotropy (Δr) were measured and observed that the anisotropy parametres are incresed with the decrease in temperature.

scholarly journals Analysis of the Part Distortions for Inconel 718 SLM: A Case Study on the NIST Test Artifact

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5087
Author(s):  
Silvia Martínez ◽  
Naiara Ortega ◽  
Diego Celentano ◽  
Antonio J. Sánchez Egea ◽  
Eneko Ukar ◽  
...  
Keyword(s):  
Inconel 718 ◽  
Thermal Gradient ◽  
Thermal Stresses ◽  
Weight Ratio ◽  
Coordinate Measuring Machine ◽  
High Strength ◽  
Inconel 718 Alloy ◽  
Geometrical Distortion ◽  
Measurement Protocol ◽  
Measuring Machine

The present paper evaluates the misalignment and geometry distortion of the standard National Institute of Standards and Technology (NIST) test artifact in Inconel 718 alloy, when several layers with and without supports are employed to manufacture it by the Selective Laser Melting (SLM) process. To this end, a coordinate-measuring machine (CMM) is used to measure the geometrical distortion in each manufacturing configuration, following the same measurement protocol. The results show that the laser path strategy favors a thermal gradient which, consequently, induces geometrical distortions in the part. To prove this hypothesis, a numerical simulation is performed to determine the thermal gradient and the pattern of the residual stresses. It was found that the geometrical distortion certainly depends on the position of the feature position and laser strategy, where thermal cycles and residual thermal stresses had an impact in the end-part geometry, especially if a high strength-to-weight ratio commonly used in aeronautics is present.

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