摘要
Nickel-based superalloys have become the key materials of micro-parts depending on excellent mechanical properties at high temperatures.The plastic deformation behavior is difficult to predict due to the occurrence of size effect on the mesoscopic scale.In this paper,the effect of specimen diameter to grain size ratio(D/d)on the flow stress and inhomogeneous plastic deformation behavior in compression of nickel-based superalloy cylindrical specimens was investigated on the mesoscopic scale.The results showed that when D/d is less than 9.7,the flow stress increases with the grain size.Aiming at this phenomenon,a flow stress size effect model considering compressive strain partitioning was established.The calculated flow stress values agree well with the experimental values,thus revealing the effect of D/d on the flow stress in compression of nickel-base superalloy on the mesoscopic scale.The inhomogeneous plastic deformation during compression deformation increases with the grain size.The end surface profiles evolve from a regular circular shape to an irregular shape with the grain size.The surface folding phenomenon occurs only in partially compressed specimen with a few grains across the diameter.Crystal plasticity finite-element(CPFE)simulation of compression deformation on the mesoscopic scale real-time displayed the evolution of microstructure.The study of this paper has important guiding significance for understanding the influence of D/d on the compression deformation behavior of nickel-based superalloy on the mesoscopic scale.
Nickel-based superalloys have become the key materials of micro-parts depending on excellent mechanical properties at high temperatures. The plastic deformation behavior is difficult to predict due to the occurrence of size effect on the mesoscopic scale. In this paper, the effect of specimen diameter to grain size ratio(D/d) on the flow stress and inhomogeneous plastic deformation behavior in compression of nickel-based superalloy cylindrical specimens was investigated on the mesoscopic scale. The results showed that when D/d is less than 9.7, the flow stress increases with the grain size. Aiming at this phenomenon, a flow stress size effect model considering compressive strain partitioning was established.The calculated flow stress values agree well with the experimental values, thus revealing the effect of D/d on the flow stress in compression of nickel-base superalloy on the mesoscopic scale. The inhomogeneous plastic deformation during compression deformation increases with the grain size. The end surface profiles evolve from a regular circular shape to an irregular shape with the grain size. The surface folding phenomenon occurs only in partially compressed specimen with a few grains across the diameter.Crystal plasticity finite-element(CPFE) simulation of compression deformation on the mesoscopic scale real-time displayed the evolution of microstructure. The study of this paper has important guiding significance for understanding the influence of D/d on the compression deformation behavior of nickel-based superalloy on the mesoscopic scale.
基金
the financial support of the project from the National Natural Science Foundation of China(Grant No.51575129)
Key Research and Development Program of Shandong Province(Grant No.2016GGX102026)
the Training Program of the Major Research Plan of the National Natural Science Foundation of China(Grant No.91860129).
