Cryogenic fatigue data developed for Inconel 718

Data were obtained on the cryogenic fatigue properties of Inconel 718 bar using axial loading and rotating beam fatigue tests. Results also disclosed the fatigue properties of Inconel 718 sheet materials

Low-temperature embrittlement of Ti-6Al-4V and Inconel-718 by high pressure hydrogen

Notched specimens of titanium alloy and Inconel-718 exhibit little reduction of notch strength at certain low temperatures under 2000 lb/sq in. hydrogen, unnotched specimens are not embrittled at these temperatures. The degree of Inconel-718 embrittlement is lower than earlier observations under 1000 lb/sq in. hydrogen

Future research directions in the machining of Inconel 718

Inconel 718 is the most popular nickel-based superalloy, extensively used in aerospace, automotive and energy industries owing to its extraordinary thermomechanical properties. It is also notoriously a difficult-to-cut material, due to its short tool life and low productivity in machining operations. Despite significant progress in cutting tool technologies, the machining of Inconel 718 is still considered a grand challenge.This paper provides a comprehensive review of recent advances in machining Inconel 718. The progress in cutting tools’ materials, coatings, geometries and surface texturing for machining Inconel 718 is reviewed. The investigation is focused on the most adopted tool materials for machining of Inconel 718, namely Cubic Boron Nitrides (CBNs), ceramics and coated carbides. The thermal conductivity of cutting tool materials has been identified as a major parameter of interest. Process control, based on sensor data for monitoring the machining of Inconel 718 alloy and detecting surface anomalies and tool wear are reviewed and discussed. This has been identified as the major step towards realising real-time control for machining safety critical Inconel 718 components. Recent advances in various processes, e.g. turning, milling and drilling for machining Inconel 718 are investigated and discussed. Recent studies related to machining additively manufactured Inconel 718 are also discussed and compared with the wrought alloy. Finally, the state of current research is established, and future research directions proposed.<br/

Effects of tin on microstructure and mechanical behavior of Inconel 718

Columbium, for which the United States is 100 percent import reliant, is of strategic importance to the U.S. aerospace industry. A major amount of the Cb is used in Inconel 718. Should Cb sources be disrupted, it may be desired to use a grade of Cb melting stock having greater Sn content then the preferred vacuum rade. Additions of Sn to Inconel 718 were varied from none added to 1 wt %. The Sn additions below 800 ppm had no detrimental effects on 650 C stress rupture behavior; however, 1-wt % Sn severely degraded both life and ductility. Additions of Sn in excess of 200 ppm were slightly detrimental to the 425 C tensile yield strength and ductility. The Sn additions had no effect on the microstructure of Inconel 718 even after stress rupture testing for over 6000 hr at 650 C

Effect of heat treatment and surface oxidation on low-cycle fatigue life of Inconel

Test program involving specimens with different heat treatment, surface condition, and chemical composition yields low cycle fatigue data on Inconel 718

Investigation of crack growth threshold of Inconel 718 exposed to high pressure oxygen Final report 24 Apr. - 25 May 1970

Crack growth threshold investigation of Inconel 718 exposed to high pressure oxyge

Ultrasonic Assisted Machining of Nickel-Based Superalloy Inconel 718

Inconel 718 has been widely used in industries because of its excellent mechanical properties. However, the machining process, particularly the turning/grinding, of Inconel 718 is still costly due to high cutting force and heavy tool damage. Fortunately, a promising material removal technique, that is, ultrasonic-assisted turning/grinding (called UAT/UAG for simplicity), could potentially play a great role in the high efficiency precision machining of Inconel 718 due to its excellent features such as smaller turning/grinding force, better surface quality, longer tool working life and lower heat generation. However, few attempts have been done on UAT/UAG of Inconel 718. Therefore, in this work, in order to confirm the feasibility of machining Inconel 718 by UAT/UAG, experimental apparatus/equipment has at first been constructed by installing an ultrasonic cutting-unit/spindle on a NC lathe/surface grinder for UAT/UAG operations, and then experimental investigations have been performed to elucidate the fundamental machining characteristics involving Inconel 718 workpiece including the effects of the ultrasonic vibration and the cutting/grinding speed on the work-surface finish, the machining force and temperature, the chip formation, the tool/wheel wears and so on. The obtained results show that grinding forces and surface roughness were decreased in UAT/UAG

Mechanism and kinetics of aging in Inconel 718

Age hardening in Inconel 718 is investigated using Brinell hardness measurements. Formation of a precipitate causes an increase in hardness

Establishment of an optimum heat treatment for use in 718 alloy bellows and gimbal structures Semiannual report, 1 Aug. 1965 - 28 Feb. 1966

Hot cracking tendencies evaluation of fusion welds of Inconel 718 alloy after different heat treatment

High Speed Finish Turning of Inconel 718 Using PCBN Tools under Dry Conditions

Inconel 718 is a superalloy, considered one of the least machinable materials. Tools must withstand a high level of temperatures and pressures in a very localized area, the abrasiveness of the hard carbides contained in the Inconel 718 microstructure and the adhesion tendency during its machining. Mechanical properties along with the low thermal conductivity become an important issue for the tool wear. The finishing operations for Inconel 718 are usually performed after solution heat treatment and age hardening of the material to give the superalloy a higher level of hardness. Carbide tools, cutting fluid (at normal or high pressures) and low cutting speed are the main recommendations for finish turning of Inconel 718. However, dry machining is preferable to the use of cutting fluids, because of its lower environmental impact and cost. Previous research has concluded that the elimination of cutting fluid in these processes is feasible when using hard carbide tools. Recent development of new PCBN (Polycrystalline Cubic Boron Nitride) grades for cutting tools with higher tenacity has allowed the application of these tool grades in the finishing operations of Inconel 718. This work studies the performance of commercial PCBN tools from four different tool manufacturers as well as an additional grade with equivalent performance during finish turning of Inconel 718 under dry conditions. Wear tests were carried out with different cutting conditions, determining the evolution of machining forces, surface roughness and tool wear. It is concluded that it is not industrially viable the high-speed finishing of Inconel 718 in a dry environment.This work was supported by the Spanish Ministry of Economy and Competitiveness and FEDER program under grant DPI2014-56137-C2-2-R