Microstructure Evolution And Mechanical Properties Of N06625 Alloy During Cold Rolling And Annealing

Nickel-based alloys have good corrosion resistance and high temperature stability.However,due to the lack of strengthening mechanism in solid solution strengthened nickel-based alloys,although they have good plasticity,their strength is relatively moderate.To solve the above problems,N06625nickel-based alloy with solid solution strengthening was selected as the research object in this paper.Incomplete recrystallization and bipeak microstructure were introduced into the alloy by cold rolling and low temperature annealing,and N06625 nickel-based alloy with excellent mechanical properties and high strength plasticity was prepared.The specific research content and results are as follows: Nickel-based alloys have good corrosion resistance and high temperature stability.However,due to the lack of strengthening mechanism in solid solution strengthened nickel-based alloys,although they have good plasticity,the strength is relatively moderate.To solve the above problems,N06625 nickel-based alloy with solid solution strengthening was selected as the research object in this paper.Incomplete recrystallization and bipeak microstructure were introduced into the alloy by cold rolling and low temperature annealing,and N06625 nickel-based alloy with excellent mechanical properties and high strength plasticity was prepared.The specific research content and results are as follows:(1)Cold rolling experiments of N06625 nickel-base alloy with different deformations were carried out.The results show that the equiaxed grains gradually change into elongated grains and their strength gradually increases with the increase of deformation amount.When the deformation amount of cold rolling reaches 60%,the grain breakage degree is large and the deformation is uneven,which can provide a prerequisite for the introduction of specific microstructure in the subsequent annealing.(2)The cold-rolled samples with 60% deformation were selected for isochronous annealing experiment.The results show that because of the uneven deformation of cold rolled samples,the high strain zone first occurs in crystallization,while the low strain zone still retains the deformed structure.Comparing mechanical properties,it is found that the tensile properties of incomplete recrystallization are better.This is because the deformation structure retained in the matrix and fine equiaxed crystals provide dislocation strengthening and fine crystal strengthening respectively.Equiaxed crystals can diverge dislocations well in the deformation process.The combination of the two helps to obtain good and balanced tensile properties.(3)The cold-rolled samples with 60% deformation were selected for isothermal annealing experiment.Through the research,it can be seen that the formation of bimodal grains is caused by the uneven deformation during cold rolling.Moreover,the bimodal grain structure can indeed make the sample have better strong plastic product,because the FGs(small grain)region contributes more to strain hardening,and the CGs(large grain)part contributes more to the plasticity of the material.The coordination of the two makes the material have better strong plastic matching.