Effects of Two Heat Treatment Processes on Mechanical Properties and Corrosion Resistance of N07718 Nickel-Based Alloy

Abstract

To investigate the effects of different heat treatment processes on the mechanical properties and corrosion resistance of nickel-based alloys，comparative tests of mechanical properties such as tension and low-temperature impact of N07718 materials with two kinds of different solid solution aging holding times were conducted using a universal tensile testing machine and a pendulum impact testing machine.At the same time，high-temperature and high-pressure H2 S/CO2 corrosion electrochemical testing equipment was used to conduct high-temperature and high-pressure electrochemical testing on the materials after two kinds of heat treatment processes.The results showed that the solid solution holding time greatly influenced the toughness and plasticity of the N07718 material but had a minor effect on its corrosion resistance.The reasons for the differences in toughness and plasticity between the two N07718 materials were analyzed through thermal field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS).An increase in solid solution aging holding time led to the precipitation of a large number of rod-shaped δ phases at the grain boundaries of the N07718 alloy material，some of which connected into chains，resulting in a decrease in material toughness and plasticity.For the N07718 nickel-based alloy，a heat treatment process involving solid solution holding treatment at 1 029.4 ℃for 1.5 h followed by water cooling，plus holding and aging treatment at 779.4 ℃for 6.5 h and air cooling，was recommended for optimal comprehensive performance.

Keywords

• n07718|δ precipitate phase|toughness and plasticity|corrosion resistance|heat treatment process