Abstract
With the rapid development of modern aviation industry, dual-property turbine disc with fine comprehensive performance plays an important role in raising the thrust-to-weight ratio of the aero-engine. For manufacturing dual-property turbine disc, the powder metallurgy superalloy (PM) with excellent creep resistance was chosen as rim material, and the wrought superalloy with fine equiaxed grains was chosen as bore material. Electron beam welding was carried out on the PM/wrought dual superalloys. Hot compression tests were conducted on the PM/Wrought dual superalloys at temperatures of 1020–1140 °C and strain rates of 0.001–1.0 s−1. Deformation behavior and microstructure evolution have been investigated to study the deformation and recrystallization mechanism during hot deformation process. The results showed that PM/Wrought dual superalloy presents the similar flow behavior to single alloys and flow stress decreases significantly with the increase of deformation temperature or the decrease of strain rate. The apparent activation energy of deformation at the strain of 0.2 was determined as being 780.07 kJ·mol−1. The constitutive equation was constructed for modeling the hot deformation of PM/Wrought dual superalloy. Meanwhile, the processing map approach was further adopted to optimize the manufacturing process for the dual-property turbine disc. Additionally, a new instability criterion was proposed: the “cliff” and “valley” in the power dissipation map are determined as sufficient conditions for flow instability. The optimum processing parameter for manufacturing the PM/Wrought dual-property turbine disc can be obtained to enhance the mechanical properties, based on the analysis of processing map technology and microstructural mechanism.
Highlights
Turbine discs are usually the most critical engine components attracting the main research attention in the field of advanced manufacturing
The powder metallurgy superalloy (PM) with excellent creep resistance was chosen as rim material, and the wrought superalloy with fine equiaxed grains was chosen as bore material
The compression specimen with diameter 8 mm and height 12 mm was machined from the welding seam of the PM/Wrought dual superalloy, which contains the base metal of PM superalloy, welding seam, and the base metal of wrought superalloy
Summary
Turbine discs are usually the most critical engine components attracting the main research attention in the field of advanced manufacturing. Metals 2019, 9, 1127 disc with fine comprehensive performance plays an important role in raising the thrust-to-weight ratio of the aero-engine. It is an effective and reliable method to fabricate the dual-property turbine disc by welding. Electron beam welding is a useful emerging technology for joining and repairing aero-engine components because it has many advantages, such as small ratio between width and depth, narrow heat affected zone, and little weld thermal deformation [2,3]. The heat-affected zone may develop grain boundary liquation micro-fissuring [4] Both of these outcomes are harmful to the mechanical properties of the electron beam weldments. Qing et al [6] explored the hot deformation behavior of the TC11/Ti−22Al−25Nb dual-alloy and obtained the optimum processing condition for the electron beam (EB) weldments during the hot working process
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