Ultrasonic Characterization of Consolidated Rapidly Solidified Powders: Application to Type 304 Stainless Steel
Rapid solidification processing (RSP) of materials is an active field with a potential for producing advanced materials with significantly improved properties compared to materials produced by conventional means. For metal powders, RSP can promote certain beneficial features of the material which depend on the cooling rate of the powder, e.g. chemical homogeneity, very fine structures such as grain size, extension of solid solutions, and the development of metastable phases 1,2. Consolidation of these powders into useful forms requires an in-depth understanding of the response of the microstructure to extrinsic consolidation parameters such as pressure (stress), temperature, and the time of application for these parameters. At the Idaho National Engineering Laboratory (INEL), a program is underway to consolidate and characterize the consolidation products of rapidly solidified Type 304 stainless steel (SS) powders. Powders produced by two different methods, centrifugal atomization (CA) and vacuum gas atomization (VGA), are being studied. Three approaches for consolidating the RSP Type 304 SS powders are being investigated: hot isostatic pressing (HIPping), hot extrusion, and dynamic consolidation with explosives. The first two methods are associated with fairly high temperatures and, therefore, present the possibility of altering the rapidly solidified microstructures.
KeywordsUltrasonic Measurement Attenuation Measurement Rapid Solidification Processing Stainless Steel Powder Helium Bubble
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