Tensile Deformation Behaviors Of GH4199Nickel-base Superalloy Under Dynamic Load

The evolution of superalloys is closely related with the improvement of aircraft turbine engine, and superalloys are the key materials which cannot be replaced in the manufacture of aircraft turbine engine, space rocket engine and industry gas turbine. With military modernization deepening, military hardware such as aircraft and naval vessel are uninterruptedly improved to the aim of high speed, bearing heavy load, integration, high accuracy and long-life on active service, so except bearing high temperature and cyclic loading, these engines equipped require superalloys’ high-speed dynamic load-bearing capability improving. Traditional design depended on static loading cannot meet the design of the advanced engine frame and properties’ demanding for.Considering material failure is a dynamic process, there had been a researcher come up with reversal design idea on the dynamic mechanical properties before, In other words, through analysing superalloys’ failure during work and studying failure mechanism, take precautions against. The study is fed back to the design of material’s composition and structure to lengthen the time on active service. Though research for the dynamic mechanical properties and failure always is proceeding by numerous researchers, the mechanism strain rate effects on the deformation behavior is not unanimous and clear for different alloys. It is very important and necessary to clear the mechanism strain rate effects on superalloys deformation behavior for the design of engine depended on actual working condition.In this paper, the research material is GH4199alloy. Research dynamic deformation behavior of the solution treated superalloys with different proportion of grain boundaries and the age treated superalloys with different size precipitated phase, analyze and explore the rule and mechanism strain rate effects on grain boundary strengthening and y’ second phase particles strengthening to provide the necessary theoretical support for the design of engine frame and material depended on dynamic mechanical properties.The results show that, with the strain rate growing, yield strength of the solution treated superalloys increases, and it increases more rapidly in dynamic load than that in static load; Tensile strength and fracture elongation had a fluctuation change, decreasing first and increasing afterwards, and get their minimum values in ε10-1s-1and102s-1respectively. When the strain rate is low, dislocation tangle is more and more serious and deformation resistance improves with strain rate growing. When strain rate grows in ε101s-1～103s-1, the number of slip system is increases, and there occur cross slipping, multi-slipping and deforming twinning when the strain rate is103s-1, which improves alloy’s deformation capacity. With the strain rate growing, the σ0which reflects the deformation resistance within grain in Hall-Petch relation increases, which is agreed with the variation of yield stress with strain rate; the K which reflects the influence of grain boundaries on deformation in Hall-Petch relation gets get his minimum values in ε10-3s-1and103s-1.For the age treated superalloys, yield strength increases with the strain rate growing, and it increases more rapidly when strain rate grows in102s-1-5×102s-1. Tensile strength and fracture elongation had a fluctuation change, decreasing slowly first and increasing rapidly afterwards, and get their minimum values in ε10-2s-1and102s-1respectively. When the strain rate is low,10-3s-1, dislocation bypasses the fine y’ second phase particles; dislocation escalades the y’ second phase particles which are bigger and stronger. When strain rate is101s-1, dislocation can incise the finest y’ second phase particles, and with the strain rate growing, the size of y’ second phase particles incised by dislocation gets bigger. With the age time extending, weakening of grain boundaries becomes serious, and intergranular cracks are obvious. With strain rate growing, intergranular cracks undergo the same age treated get bigger, and strain rate sensitivity is critical. When TCP phase rely on grain boundaries, weakening of deformation is serious, and strain rate sensitivity is critical; When TCP phase lie during grain, weakening of deformation is relatively slight.