Tensile Properties Of Haynes230 Nickel Base Alloy At High Temperature

Haynes230 nickel-based alloy is easy to be molded because of its good high temperature strength,excellent oxidation resistance,corrosion resistance,nitrogen resistance and thermal stability.It is widely used in the manufacture of aircraft turbine engine combustion chambers and flame tubes.The components are also widely used in the manufacture of high-temperature equipment components such as surface gas turbine combustor components and industrial furnace thermocouple protection tubes and hot cyclone linings.Applications in the chemical industry include catalyst grids and high temperature heat exchangers for the nitric acid industry.In this paper,the high temperature tensile properties of Haynes230 nickel-based alloys were investigated.First,tensile tests were carried out at five temperatures of normal temperature,650°C,700°C,760°C,and 800°C.The results show that the yield strength of the material decreases significantly with increasing temperature,from 444 MPa at RT to 252 MPa at 800°C.However,in general,in the temperature range of 650°C?760°C,the temperature has little effect on the yield stress,and is maintained at ?300MPa.The work hardening rate—flow stress before yielding after yielding at different temperatures is linear.As the temperature increases,the fraction of the straight section gradually decreases throughout the work hardening,which is related to the decrease of the proliferation rate of the linear dislocation at high temperatures.Secondly,the temperature dependence of the DSA effect of Haynes230 nickel-based alloy was analyzed.The temperature dependence of the number of sawtooth and the maximum stress drop indicates that the material has a significant DSA effect at 650°C.When the temperature is raised from 650°C to 760°C,the DSA effect gradually decreases;as the temperature rises to 800°C,again Promote the occurrence of the DSA effect.The critical strain calculation results of DSA effect at different temperatures also confirmed that the DSA effect is more likely to occur at 650°C than 760°C and 800°C.The difference in the diffusion rate of solute atoms in the material at different temperatures causes the DSA effect to be not linear with temperature.Finally,electron backscatter diffraction(EBSD)was used to analyze the fractures of the matrix and tensile experiments.The results show that the main microscopic deformation mode at room temperature is in addition to dislocation slip and {111}<11-2> twinning.The increase of the volume fraction of the twin boundary increases the work hardening rate;at high temperatures,the twin deformation is suppressed,the strengthening effect of the twin boundary and the coordination effect of the twin deformation are weakened,resulting in a decrease in the macroscopic mechanical properties of the material.At 760°C and 800°C,the tensile deformation mode is mainly changed to intergranular deformation.Dynamic recrystallization and grain growth form a two-state structure,and the material properties deteriorate rapidly.The results of this paper can provide a reference for improving the production process of this material.