I think there are some reasons, but I can't find that.
In my thought, the HIPed superalloy is homogeneous, has no porosity there and many advantages.
So, there are many cases of the applications for turbine discs.
However, it seems that there is no application for turbine blades even though the HIP is used for rejuvenation of turbine blades due to the reduction of porosity.
In my reference book, it is explained that the wrought alloy is used for the intermediate-temperatrature and the cast alloy is for high-temperature.
Unfortunately, the book didn't answer why.
If there is any case. please introduce to me.
No. It is possible to fabricate superalloy with PM.
Consider the advantages of cast single crystal turbine blades vs. the likely very fine grained, polycrystalline HIP'd material
Thanks for your answers, Gunjal and Young.
Then, how about making the polycrystal HIPed material singlecrystal?
I mean, the PM material would be better than the cast one.
Is it unreasonable? Or, is it a kind of economical or technical problem?
It is a technical problem - in order to make a large single crystal you need to melt and directionally solidify. There is no practical way in the solid state as far as I know.
As far as I know, there are many internal cooling hole in the high pressure turbine blade,Which can further increase the service temperature. And this hollow structure can be made by investment casting easily, it seems impossible through PM route. Another is the microstructure difference, usually, the wrought alloy's grain is equiaxed, in the high temperature, the existence of the grain boundary greatly reduce the creep property.
For detailed information, you can refer to this book.
Reed R C. The superalloys: fundamentals and applications[M]. Cambridge university press, 2006.
Depends upon the application we have to maintain the micro structure and homogeneity . other wise no problem.
Higher the TET (turbine entry temperature) better the efficiency... That is the base line, We have complex internal cooling channels for turbine blades and such blades can be produced only through Investment casting process. HIPPing may not be able to produce these geometries.
Also Single crystal blades produced have better creep properties (which is the most imp property deciding the life at High temperature and high stresses a typical turbine blade faces)
Again Hipping may Not yield such properties.
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