Effects of Temperature and Pressure of Hot Isostatic Pressing on the Grain Structure of Powder Metallurgy Superalloy

Abstract

The microstructure with homogeneously distributed grains and less prior particle boundary (PPB) precipitates is always desired for powder metallurgy superalloys after hot isostatic pressing (HIPping). In this work, we studied the effects of HIPping parameters, temperature and pressure on the grain structure in PM superalloy FGH96, by means of scanning electron microscope (SEM), electron backscatter diffraction (EBSD), transmission electron microscope (TEM) and Time-of-flight secondary ion spectrometry (ToF-SIMS). It was found that temperature and pressure played different roles in controlling PPB precipitation and grain structure during HIPping, the tendency of grain coarsening under high temperature could be inhibited by increasing HIPping pressure which facilitates the recrystallization. In general, relatively high temperature and pressure of HIPping were preferred to obtain an as-HIPped superalloy FGH96 with diminished PPB precipitation and homogeneously refined grains.

Evolution of the Microstructure and Mechanical Properties of a Ti35Nb2Sn Alloy Post-Processed by Hot Isostatic Pressing for Biomedical Applications

“…The large amount of beta stabilisers (niobium) in the alloy's composition contributed to lower Young´s modulus, with values of 70 GPa, which improved the current 100 or 110 GPa that today's titanium alloys employed in prosthesis present (Ti CP and Ti6Al4V ELI), and may minimise bone atrophy due to the stress shielding effect, which increases implant durability. L. Tan et al (2018) studied the precipitation phenomenon, the prior particle boundary (PPB), that occurs during HIPing and justify the lower deformation values on titanium samples. Plastic deformation metallurgic process, such as hot forging, cold drawing, and ECAP, modifies the grain dimension and morphology, minimizing the impact from PPB The α+β regions with fewer refractory elements displayed high chemical heterogeneity.…”

“…L. Tan et al (2018) studied the precipitation phenomenon, the prior particle boundary (PPB), that occurs during HIPing and justify the lower deformation values on titanium samples. Plastic deformation metallurgic process, such as hot forging, cold drawing, and ECAP, modifies the grain dimension and morphology, minimizing the impact from PPB precipitation on PM parts, and increasing the strength of the titanium alloys [18].…”

Critical Raw Materials Saving by Protective Coatings under Extreme Conditions: A Review of Last Trends in Alloys and Coatings for Aerospace Engine Applications

“…Ni-base superalloys may contain up to As an alternative to the casting process of the melted alloy, powder metallurgy is also employed for the fabrication of single crystal turbine blades. In this technique, superalloy powders obtained from the initial melting stage are then further processed and consolidated by hot isostatic pressing (HIP) [38,39]. This method is reported to allow alloying more elements with uniform composition, grain size, and phase composition, and with reduced segregation and porosity.…”

Determining the influence exerted by the static conditions of final squeezing on the compaction process of iron-based powder materials

“…The disadvantages of this method are low performance, as well as low resistance of graphite press equipment, which limits its use in manufacturing. The shortcomings of hot pressing are partially overcome by the technology of SPS (spark plasma sintering) involving the electric-charge or spark-plasma sintering [4]. However, the SPS method is mainly used for processing ceramic materials, which, in the conditions of free baking, have a high residual porosity even with a long time of isothermal aging [5].…”