Ti合金粉末HIP材の超塑性鍛造

概要

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Titanium alloy GT33 was designed by NRIM to have good superplasticity at working temperature and superior mechanical properties at service temperature.<BR>We examined the processing characteristics, the mechanical properties and the superplastic behavior of P/M GT33 alloy. GT33 alloy powder was made by plasma rotary electrode process and equipment was improved to produce fine and rapidly solidified powder. Mean particle diameter was decreased from 180μm to 85μm and cell size was decreased from 6μm to 1μm. The flow stress of HIPed preforms became to half of original one and superplastic elongation was doubled. HIPed GT33 preforms were successfully forged superplastically to φ400mm fullscale model disc with twisted blades (blisc). The forged and double solution heat treated GT33 alloy showed a high strength to density ratio at 300°C up to 28.6×10<SUP>6</SUP>mm with 11.3% elongation.<BR>Furthermore, dual property disk which shows high strength at boss portion and high creep resistance at rim was made by partial hydride-dehvdride Process.