Showing papers on "Inconel published in 1987"

Thermal conductivity of Inconel 718 and 304 stainless steel

Abstract: The results of thermal conductivity measurements on Inconel 718 and 304 stainless steel by the comparative and flash diffusivity techniques are reported for the temperature range 0–700°C For 304 stainless steel, excellent agreement with published data is found for the specific heat, thermal diffusivity, and thermal conductivity In the case of Inconel 718, the measurements show that the conductivity depends critically on the sample thermal history and the metallurgical condition of the alloy Measurements on a solution-treated sample indicated a conductivity function close to that reported previously, while precipitated samples showed a higher conductivity, similar to the conductivityvs-temperature function used for reduction of comparative thermal conductivity data with Inconel 718 references These results indicate that Inconel 718 is not a suitable reference for high-accuracy comparative thermal conductivity measurements unless its thermal history and associated conductivity function are known

High temperature alloys : their exploitable potential

Abstract: List of Contents.- Preface.- Opening Session.- Chairman: M. Van de Voorde, C.E.C., Joint Research Centre, Petten Establishment, Petten, NL..- Welcome and Opening of the Conference:.- Opening Thoughts - the Future of High Temperature Materials.- E.D. Hondros, Director of the Joint Research Centre, Petten Establishment, Petten, NL..- Keynote paper:.- The Capability of Current Materials in Relation to Future gas Turbine Needs.- G. Meetham, Rolls Royce Ltd., Derby, UK..- Session 1: Theoretical and Practical Limits of HT Alloys. Sub-session 1.1.: Chairman: S. Amelinckx, SCK-CEN, Mol, B..- Mechanical Properties of Nickel Base Alloys in Relation with their Microstructure (Abstract).- Modelling Creep and Fracture in Engineering Alloys.- High Temperature Creep Mechanisms in Single Crystals of Some High Performance Nickel-Base Superalloys.- Dislocation Microstructure in PM Astroloy and Ma6000 after HTLCF.- Ferritic Fe-Ni-Al Alloys for High Temperature Applications.- Metallographic Indication of Methane in Steel Cavities.- Rapporteur's synthesis.- Sub-session 1.2.: Chairman: G. Sainfort, CEA, Grenoble, F..- The Corrosion Behaviour of Alloys in High Temperature Gaseous Environments.- The Limits to the Protective Effect of Oxide Scales on High Temperature Materials Which are Subjected to Strain.- Relaxation of the Mechanical Stresses Developed Through Oxide Scales During Oxidation of Metals.- The Effects of Cerium and Cerium Oxide on the High Temperature Oxidation of Iron-Chromium Alloys at Iooo DegreesC in 100 Torr O2.- The Carburisation Behaviour of Steels for Petrochemical Plant.- An Evaluation of Fe-Cr-Al Alloys in Simulated Coal Gasifier Environments from 850-1050 DegreesC.- Environmental Resistance oF Incoloy alloy Ma956.- Identification of Oxide and Sulphide Corrosion Products Using Raman Microscopy.- The Sulphidation Behaviour of Vanadium, Niobium and Molybdenum.- The Influence of Alloy Composition Upon The Corrosion Behaviour of 25Cr-35Ni-Fe Alloys Exposed to Mixed Gaseous Oxidising/Sulphidising/Carburising Atmospheres.- High Temperature Sulphidation of Aluminised Alloys: Protective Properties of Alumina Layers.- The Laser Raman Microprobe - A New Technique for the Identification of Corrosion Scale Constituents.- Rapporteur's Synthesis.- Session 2: Potential for Development in Alloys and Processing. Sub-session 2.1.: Chairman: J. Levy, Ecole des Mines, Paris, F..- Steel and Nickel Base Alloys.- Production and Properties of Large Nimonic Alloy 901 Discs for Land-Based gas Turbines.- Development of 12Cr-1Mo-1W-V-Nb Steel for Elevated Temperature Applications.- Service Experiences of 12Cr-1Mo-W-V-Nb Steel and 9Cr-2Mo Steel in a Power Boiler.- An Austenitic Heat Resisting Steel Tube Developed for Advanced Fossil-fired Steam Plants.- Hot Working of Duplex Stainless Steels and Nickel-Iron Superalloys.- Development of a Duplex Structure 12Cr-1.5Mo-1W Steel for Elevated Temperature Applications.- The Influence of Powder Processing Variables on the Structure and Properties of Hiped Low Carbon Astroloy.- Sensitivity of Mechanical Properties of Nickel Base Alloys to Cooling rates.- Effects of Cobalt on the Microstructures and Mechanical Properties of the Fe-Ni-Co Base Superalloy Refractoloy 26.- Properties and Applications of Hot Formed O.D.S. Alloys.- Influence of Regeneration Treatments on Creep Rupture Lifes of Turbine Blades.- Rapporteur's Synthesis.- Sub-session 2.2.: Chairman: J.F. Conde, Admiralty Marine Technology, Poole, UK..- Coatings - their Potential and Limits (Abstract).- Diffusion Phenomena Between Coating and Base Material in Ni-Base Superalloy.- The High Temperature Oxidation Behaviour of the Single Crystal Ni-Base alloy M002 Mod. with and without Protective Coatings.- Rapporteur's Synthesis.- Session 3: Engineering Considerations. Sub-session 3.1.: Chairman: J. Schijve, Technical University, Delft, NL..- Thermo-Mechanical Loading Constraints (Abstract).- Fatigue and Microstructure.- Low Cycle Fatigue Behaviour of Inconel Alloy 617.- Influence of Heat Treatment on Fatigue of Inconel 718 Alloy at 650 DegreesC.- Rapporteur's Synthesis.- Sub-session 3.2.: Chairman: J.R. Donati, Electricite de France, Moret, F..- Factors Governing Design Rules for HT Components.- Analysis of Exhaustion and Damage on Creep-Exposed Components.- Corrosion and Creep of Nickel-Base Alloys in Steam Reforming GAS.- The Creep Ductility and Fracture of Carburised Alloy 800H at HIGH Temperatures.- Qualification of Stationary Creep of the Carbide Precipitating Alloy 800H.- Rapporteur's Synthesis.- Session 4: Future Outlook. Chairman: H. Nickel, K.F.A., Jiilich, FRG..- The Potential and Problems of Engineering Ceramics (Abstract).- Contribution to the Quantification of the Development Potential of High Temperature Alloys.- Rapporteur's Synthesis.- Final Discussion.- Rapporteur's Synthesis.- List of Participants.

Mixed mode small crack growth

Abstract: — The fatigue crack growth behavior of small part-through cracks in 1045 steel and Inconel 718 subjected to biaxial loading has been investigated. Experiments were performed on thin-wall tubular specimens loaded in tension, torsion and combined tension torsion. Crack sizes analyzed ranged from 20 μm to 1 mm and growth rates ranged from 10-7 to 10-4 mm/cycle for 1045 steel and from 10-5 to 10-2 mm/cycle for Inconel. Nucleation and the early growth of cracks occurs on planes of maximum shear strain amplitude for both of these materials even in tensile loading. An equivalent strain based intensity factor was employed to correlate the crack growth rate under mixed mode loading conditions In loading conditions other than torsion, a transition from mode II to mode I was observed for 1045 steel. Principal strains were used to analyze mode I cracks. Cracks in Inconel 718 grow in mode II for the majority of the fatigue life. The maximum shear strain amplitude and the tensile strain normal to the maximum shear strain amplitude plane were used to calculate the strain based intensity factor for mixed mode loading.

Creep crack initiation and growth in inconel 718 alloy at 650°c

Abstract: Creep cracking tests were performed on a nickel base superalloy, Inconel 718, using CT type specimens at 650°C in an air environment. Both time to initiate creep crack propagation (T1) and creep crack growth rate (ȧ) were measured as a function of the stress-intensity factor, K. It is shown that crack initiation behaviour and early crack growth (stage I) are strongly dependent on test procedures. Furthermore there is no unique correlation between ȧ and K, except in the regime corresponding to relatively high crack growth rates (stage II). This conclusion was reached by conducting tests both under increasing and under decreasing K. The reasons for this behaviour are briefly discussed in relation to environmental effects. A simple model (based upon a theoretical stress-strain field for creeping cracked solids and the ductility exhaustion concept) is used in an attempt to explain the results. The limitations for the application of this model are discussed. It is shown that this approach can explain a number of experimental results provided that it is accepted that creep ductility is time-dependent because of environmental effects. Finally, the results of these crack propagation tests are used in conjunction with the theoretical results derived from the Riedel and Rice analysis to model both crack initiation and crack growth behaviour of Inconel 718 under sustained load.

LASER CLADDING OF Ni-Cr-Al-Hf ON INCONEL 718 FOR IMPROVED HIGH TEMPERATURE OXIDATION RESISTANCE.

Abstract: In-situ Ni-Cr-Al-Hf alloy was developed by laser surface cladding with a mixed-powder feed for improved high-temperature oxidation resistance. Oxidation-resistant materials for operation at elevated temperatures must satisfy two requirements: diffusion through the oxide scale must occur at the lowest possible rate, and the oxide scale must resist spallation. Formation of an Al/sub 2/O/sub 3/ protective scale fulfills the former requirement but its adherence is poor. A reactive metal such as Hf is added to improve adhesion. A 10-kW CO/sub 2/ laser was used for laser cladding. Optical, SEM and STEM microanalysis techniques were employed to characterize the different phases produced during the cladding process. Microstructural studies showed a high degree of grain refinement, increased solid solubility of Hf in the matrix and the formation of Hf-rich precipitates. A thermogravimetric analysis was carried out to determine the oxidation properties of these clad alloys with an extended solid solution of Hf. Considerable improvement over the base metal was observed. This paper discusses microstructural development in this laser-clad alloy and its effect on oxidation.

Vapor-deposited emittance-catalysis coatings for superalloys in heat-shield applications

Abstract: Statically oxidized Inconel 617 and MA 956 superalloys were prepared with vapor deposited aluminosilicate layers and exposed to temperatures which simulated reentry conditions. The aluminosilicate layers were 1-2 microns thick. The trials consisted of exposures to 1500-2300 F heat while surface temperatures were monitored with pyrometers. Analyses were then performed of the catalytic activity, oxidation phenomena, and radiative properties after thermal cycling the specimens for 8 hr. Both alloys were found to be catalytic to the recombination processes of dissociated species in the reentry environment. The coatings reduced the catalytic activity by 40 percent for both alloys but did not change the emittance. An enhanced Cr depletion zone was detected in the Inconel samples, implying that the coating did not prevent diffusion loss of Cr. The coated MA 956, on the other hand, gained weight over the course of the trials.

Characterization of INCONEL alloy MA 6000 powder

Abstract: Mechanically alloyed powders of INCONEL* alloy MA 6000 have been characterized in order to understand the mechanical alloying process. Various analytical techniques including transmission electron microscopy, X-ray diffraction, electron microprobe analysis, and Auger electron spectroscopy were used to reveal the microstructural changes, chemical homogeneity, degree of mechanical working, and surface chemistry of powders during the powder processing. The current investigation has brought about a better understanding of the basic mechanism of the mechanical alloying process as well as a guideline for quality control of mechanically alloyed powder.

Vapour-phase siliconizing of some nickel-base alloys and transition metals using Si2Cl6 as a source of silicon

Abstract: Some nickel-base alloys and transition metals were siliconized using hexachlorodisilane (Si2Cl6, b.p. 144° C) in the temperature range 500 to 1000° C, and subsequently their corrosion stabilities were examined. Using hexachlorodisilane as a silicon source, the siliconizing temperature could be lowered by 150° C for Monel, 200° C for Inconel (No. 600), 50° C for titanium and 150° C for molybdenum in comparison with that using silicon tetrachloride. The corrosion stability of Inconel plate against 1N H2SO4 and 1N HNO3 were improved considerably by the siliconizing of the surface. On the other hand, that of Monel against 1N H2SO4 was improved outstandingly by the siliconizing of the surface, but not improved against 1N HNO3.

High-temperature corrosion of LPPS-coated inconel alloy MA 6000

Abstract: A low-pressure plasma spray (LPPS) coating of a commercial NiCoCrAlY(Ta) alloy on Inconel alloy MA 6000 was examined metallographically after 500 h of cyclic oxidation and burner rig testing for coating performance and interfacial reactions. Uncoated Inconel alloy MA 6000 was also examined for oxidation and hot corrosion resistance. Bare Inconel alloy MA 6000 has excellent oxidation resistance to 2010 °F (1100 °C) but is subject to internal sulfidation in burner rig testing at 1700 °F (925 °C) and 2000 °F (1095 °C). An LPPS coating of a NiCoCrAlY(Ta) alloy protected the Inconel alloy MA 6000 substrate from oxidation and sulfidation for 312 h at both temperatures but developed appreciable interfacial voiding after 500 h at 2000 °F (1095 °C). Spalling of the coating was observed only on burner rig test specimens run at 2000 °F (1095 °C).

Influence of Microstructure on the Environmentally Assisted Cracking of Inconel 718

Abstract: The effect of grain boundary precipitation on the environmental behavior of Inconel 718 was determined. The performance of conventionally heat treated (CHT) material was compared with that of direct-aged (DA) material. Straining electrode tests with cathodic polarization at room temperature and fatigue tests in aqueous environments ranging from 30 to 288 C were performed. Microstructurally, direct aging was found to reduce the size and amount of grain boundary precipitates significantly. A decrease in the amount of grain boundary precipitation results in a reduction of grain boundary cavitation and an increase in ductility during straining electrode tensile tests. Grain boundary cavitation does not affect tensile properties in air. However, cathodic polarization during tensile testing significantly embrittles the CHT condition relative to the DA condition. Direct aging does not affect fatigue crack growth rates in aqueous environments at temperatures ranging from 30 to 288 C.

Effect of niobium on marine crevice corrosion resistance of Inconel alloy 625

Abstract: The crevice corrosion resistance of Inconel alloy 625 has been investigated as a function of its niobium content. A technique used primarily for mathematical modelling of crevice corrosion in chloride media has been used to compare the probable resistances to this type of corrosion. It has been shown that the level of niobium can be reduced from that in the commercially available alloy – thereby offering a more cost effective alternative – while maintaining favourable crevice corrosion resistance and mechanical properties. In addition, it was found that a solution annealing treatment of the alloy variations produced further beneficial properties in the alloy.

Effect of carbide precipitation on the corrosion behavior of Inconel alloy 690

Abstract: Intergranular carbide precipitation reactions have been shown to affect the stress corrosion cracking (SCC) resistance of nickel-chromium-iron alloys in environments relative to nuclear steam generators. Carbon solubility curves, time-temperature-sensitization plots and other carbide precipitation data are presented for alloy 690 as an aid in developing heat treatments for improved SCC resistance.

Post-compaction heat-treatment response of dynamically-compacted Inconel 718 powder

Abstract: Dynamically-compacted Inconel 718 powder has been heat treated in order to examine the evolution of microstructural recovery and hardness, recrystallization and grain coarsening, and interparticle-adhesion and fracture response. Following dynamic compaction the compacted powders are imperfectly bonded and the material is fairly brittle; the shock wave has caused significant hardening; local microstructures and properties are variable from particle surface to interior. Following annealing at 900 to 1000° C, virtually complete recrystallization occurs giving rise to a material which is softened and has a fine-scale microstructure. Little improvement in fracture response occurs, however, because the oxidized prior-particle surfaces do not weld together. Shock-wave consolidation offers the possibility of producing monolithic, microstructurally-fine materials, providing suitable post-consolidation thermo-mechanical processes are developed to overcome the limited bonding problem.

The effect of the lower stress level on the cyclic creep behavior of an ods superalloy

Abstract: Cyclic creep and stress rupture results are reported and discussed as a function of the lower applied load for INCONEL MA6000, which is a mechanically alloyed oxide dispersion strengthened (ODS) and γ’ precipitation strengthened nickel-base superalloy. In prior work, very large decreases in the effective minimum cyclic creep rate, based on time at maximum load, were found to occur for cyclic creep testing using a lower load near zero. The present results show that this decrease in creep rate depends on the value of the lower load. As the lower load increases, the cyclic creep rate increases proportionally, but remains less than the corresponding static creep rate. The values of the cyclic creep rates are shown to be related to the magnitude of the anelastic strain recovery occurring during the lower load portion of the cyclic creep test. The results are also used to improve on the anelastic relaxation model for cyclic creep of materials with strong pinning points.

Sputter-coating of Ti-6Al-4V with inconel 617 for erosion resistance

Abstract: Inconel 617 and reactively sputtered Inconel 617 nitride coatings 26 – 28 μm thick were magnetron sputtered onto glass and titanium substrates at 1900 A min −1 and 1400 A min −1 respectively, and then characterized. Sputtered Inconel 617 coatings are smooth, adherent and ductile, with a b.c.c. structure. Equiaxed grains ranging in size from 300 to 1000 A in diameter were found. Nitrided Inconel 617 is brittle, adherent, and has a two-phase structure consisting of fine crystallites, tentatively identified as f.c.c. Ni 4 N, embedded in a semicrystalline matrix, and was found to be 38% harder than the non-nitrided coating. Sputtered Inconel 617 could not be compared with the Thornton zone model, but the nitrided coating corresponded well to a Zone T structure. Coatings deposited on Ti-6Al-4V were eroded at 90° with 15 μm SiC at a velocity of 67 m s − in order to examine the mechanisms of erosion. Both coatings exhibited ductile mechanical behavior at single impact sites. The cutting mechanism was prevalent. Embedded and fragmented erodent was also found.

Ni-base coated arc welding material of low si

Abstract: PURPOSE:To prevent the generation of microcracks in a weld metal by decreasing the content of Si in an Ni-base coated arc welding material. CONSTITUTION:The content of Si in the Ni-base coated arc welding material is decreased so that the content of Si in the weld metal consisting of said welding material is <=0.20wt%. As a result, the formation of the Ni-Si low melting eutectic metal in the weld metal is suppressed and the generation of the microcracks is prevented. This welding material is suitable for welding of products made of 'Inconel(R)', stainless steel, iron and steel materials, etc.

Creep Feed Grinding of Inconel 718 with Continuous Dressing : Series C : Vibration, Control Engineering, Engineering for Industry

Abstract: Nickel-iron base superalloy (Inconel 718) is used extensively for various high-strength, high-temperature components of aircraft engines. However, it is extremely difficult to machine. In this study, creep feed grinding with continuous dressing is applied to grind Inconel 718. Through the experiments it is confirmed that this new machining method is very efficient for difficult-to-machine materials such as Inconel 718, i.e., the productivity and the machining accuracy are markedly improved.

Nickel alloy having superior hot workability and creep rupture characteristic at high temperature

Abstract: PURPOSE:To obtain the titled Ni alloy by adding a prescribed amount of Y or Mg to the composition of an Ni alloy called 'Inconel 718(R)'. CONSTITUTION:0.005-0.15% Y and/or 0.01-0.03% Mg is added to an Ni alloy consisting of, by weight, 50-55% Ni, 17-21% Cr, 4-6% Nb and Ta, 2-4% Mo, 0.1-1.5% Al, 0.1-2% Ti and the balance Fe. The resulting alloy has considerably improved hot workability and creep rupture characteristics at high temp. as compared with 'Inconel 718(R)'. The rupture time of the alloy is about twice as that of the 'Inconel 718(R)' and the alloy has a remarkably prolonged rupture life.