High-temperature alloy fasteners

Inconel 718 is a Ni-Cr-Fe-Nb precipitation-strengthened nickel-based superalloy. The strengthening phases are body-centered square γ'' phase and face-centered cubic γ' phase. The domestic designation is GH4169. Compared with other high-temperature alloys, Inconel 718 has good thermal stability and corrosion resistance, and has excellent fatigue and creep durability at temperatures below 650 ° C. Therefore, it has been widely used in various hot-end parts of aero-engines [1-3]. Inconel 718 twelve-point countersunk head bolt is a representative product of high-temperature and high-strength aerospace fasteners. The head is usually formed by hot heading, and the deformation of the head is relatively large during processing. Due to the complex alloy phase composition and various structures of Inconel 718 material, the process plasticity is poor, and the deformation resistance during hot working is relatively large, so the difficulty of hot forming is increased. Especially for twelve-point countersunk head bolts with countersunk head cones, the complex head shape further aggravates the inhomogeneity of the temperature field during thermal processing, making the stress distribution characteristics more complicated than conventional twelve-point countersunk head bolts. The processing performance deteriorates, and it is difficult to guarantee the size, metallographic and performance requirements of the parts. In this paper, aiming at the material properties and structural characteristics of Inconel 718 twelve-point countersunk head bolts, the processing quality of the head forming is improved by adjusting the mold structure and heating temperature of the hot heading process, and at the same time, the key dimensions of the head are guaranteed by the turning process to improve the bolt Production efficiency and pass rate to ensure the smooth delivery of the parts.

Monel alloy, also known as nickel alloy, is an alloy made of metal nickel as the base and adding copper, iron, manganese and other elements.

Monel is a group of alloys of nickel (from 52 to 67%) and copper, with small amounts of iron, manganese, carbon, and silicon. Monel is not a cupronickel alloy because it has less than 60% copper. Stronger than pure nickel, Monel alloys are resistant to corrosion by many aggressive agents, including rapidly flowing seawater. They can be fabricated readily by hot- and cold-working, machining, and welding.

A superalloy, or high-performance alloy, is an alloy with the ability to operate at a high fraction of its melting point. Several key characteristics of a superalloy are excellent mechanical strength, resistance to thermal creep deformation, good surface stability, and resistance to corrosion or oxidation.

Hastelloy fasteners are resistant to some of the most severe chemicals, this very material often finds use in oil & gas sour gas service, chemical processing, power industries flue gas desulfurization systems, off-shore oil and down hole environments, pulp & paper bleaching and digesters, as well as other industrial facets where corrosion is an issue.