4/1/2023 0 Comments Al element![]() ![]() In addition, the δ phase in the microstructure is significantly reduced. After the HIP treatment of the as-cast IN718 superalloy, Chang found that the γ″ phase nucleates at the γ′/ γ interface and merges with the γ′ phase to form the γ′/ γ′′ eutectic phase. found that the size and the volume fraction of γ′ precipitates were significantly improved and the morphology of carbides at the grain boundary changed from linear to granular. After HIP of the as-cast K403 superalloy, Zhang et al. As HIP is carried out under high-temperature and high-pressure conditions, it can effectively reduce the eutectic structure, homogenize the composition, and improve grain size and dendrite segregation. It uses the combined effect of high temperature and high pressure to densify the internal structure of metal castings and forms a circular creep raft structure around the pores, resulting in effective healing of metallurgical defects such as pores and segregation in the alloy. Hot isostatic pressing (HIP) technology is applied to solve the problem of shrinkage metallurgical defects. Although the casting process has been constantly improved and micrometallurgical defects in superalloy castings have been reduced to a certain extent, it cannot completely eliminate the micrometallurgical defects such as shrinkage and the volume fraction of shrinkage content that can generally reach more than 0.3%. ![]() With the continuous development of advanced blades, micrometallurgical defects, such as pores, shrinkage, and slag patches, inevitably appear in the casting process. K417G, a nickel-based precipitation-hardened cast superalloy, has excellent high-temperature mechanical properties and hot-corrosion resistance after being modified on the basis of K417 superalloy and is used for turbine blades and guide blade components of aircraft engines. However, the service condition of the aero-engine gas turbine is extremely severe, and superalloys play a crucial role in the high-temperature condition. Since the 1940s, casting superalloys have been rapidly developed in the aerospace field and are widely used in aero-engine turbine blades. The changes in the γ′ phase and the deformation mechanism after HIP are discussed. ![]() In addition, the elongation after HIP is increased by about 60% compared to the as-cast alloy, with an average of 4.7%. The stress rupture life at 760☌ and 645 MPa of alloys after HIP at 1175☌ and 1185☌ increased by 90 h and 20 h, respectively, compared with the as-cast alloy, but it is not the case for HIP at 1195☌. ![]() As the HIP temperature increased from 1175☌ to 1195☌, the microporosity and eutectic are further reduced slightly. In addition, the area fraction of ( γ + γ′) eutectic decreases, dendritic segregation is improved, and the element distribution is homogenized. The cubic γ′ precipitates grow up, accompanied by the precipitation of the fine γ′ phase in the matrix. After HIP, the average microporosity of alloy after HIP is 0.04%, which is reduced by nearly 90% compared with the as-cast microstructure. The results show that the stress rupture property of the alloy is improved by the appropriate HIP process. The effect of hot isostatic pressing (HIP) on the stress rupture property of K417G nickel-based superalloy is studied experimentally. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |