Study Of Microstructures And Properties Of GH4169Superalloy

This paper studies the high-temperature creep properties of by superalloy GH4169different processing technology and different heat treatment. Also, its high-temperature tensile properties after different solution treatment temperature has been studied. By using optical microscopy, SEM, EDS current controversial8phase issues have been discussed in-depth.Meanwhile the paper studied how8phase affect the performance of GH4169high temperature creep. For high-temperature creep, two processing methods of GH4169alloy (diameter forging and hot rolling) were taken and two different ways on heat-treated were adapted,Experimental results show that:1) With less8phase temperature the creep performance of hot rolling GH4169alloy is better than those with more8phases processed by radial forging.2) In order to prove that the heat treatment has a significant impact on the amount of high-temperature creep properties and phase8GH4169alloy, picking the specimens processed by hot rolling to make different hot treatments, with standard heat treatment and direct aging treatment. The specimens of GH4169with direct aging treatment nearly had no8phase presence in the grain boundary and grain, high-temperature creep results showed that after hot rolling of GH4169, the specimens through aging process are substantially free from8phase, the creep life is far greater than through standard treatment ones. The hot-temperature creep life of the specimens through direct aging treatment is twice as many as those through standard hot treatment. The8-phase precipitates at the grain boundaries generally, grain boundary precipitation of8will cause pinning effect, strengthening the grain boundaries, preventing the expansion of the grain boundary sliding and creep crack, which in a certain extent, improve the creep resistance of the alloy, but with the precipitation of8phase, it will also consume strengthening phase y "in Nb elements in the superalloy, thereby reducing the y" number of phases, resulting in a decrease the strength. Thus the creep properties with no8-phase from the specimens through direct aging treatment are best. A large number of8-phase at the grain boundary evolves a pinning effect, preventing further slippage of the grain boundary. So the grain boundary empty is not smoothly connected together. Thus, the slip is then generated in the grain interior. It was after the fracture mechanism Trail ST GH4169alloy forging transgranular fracture. Almost no phase precipitation at grain boundary, so once the grain boundaries began to slip without any obstacles, it will result in the least elongation at break time for direct hot rolling alloy. The fracture mechanism is intergranular fracture. The hot rolling alloys with standard treatment have a fewδ-phase, only a small amount of8-phase appear at grain boundaries. Cracks formed at first in the grain boundary phase which ha8phase in it. Because δ phase has less effect in curing, the crack extends fast. Thus, elongation is the least and the fracture type is intergranular fracture.We adopt high temperature experiment to discuss the effect of δ phase on the tensile properties of GH4169superalloy. The specimens are from the forging GH4169, and before the high temperature tensile experiment, those specimens have been treated by solution treatment and standard treatment respectively. The experiment results are as follows:at the950℃, the stress strain curve of GH4169superalloy is a typical elastic-even plastic type. During the even deformation stage, the GH4169treated by standard heat treatment show a single matrix y phase deformation, its strain hardening exponent n is0.124. But the sample treated by solution treatment has two deformation stages, the strain hardening exponent n in the first stage is0.067, and in the second stage the n is0.035, the n in the first stage is bigger than one in the second stage. The tensile ductility of the two types of GH4169superalloy is85and68respectively at the950℃. The tensile failure type for the two samples is ductility fracture, and the fracture mechanism is micropore gather type, and the core of this fracture is Sphase and some Carbonizable Substance.