Aging and Phase Stability of Alloy 22 Welds FY05 SUMMARY REPORT

Torres, S G ; El-Dasher, B ; McGregor, M ; Etien, R ; Edgecumbe, T S ; Gdowski, G ; Yang, N ; Headley, T ; Chames, J ; Yio, J L ; Garcdea, A

Lawrence Livermore National Laboratory

关键词: Corrosion;    Aging;    Alloys;    Phase Stability;    Processing;   

DOI  :  10.2172/889961
RP-ID  :  UCRL-TR-217339
RP-ID  :  W-7405-ENG-48
RP-ID  :  889961

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来源: UNT Digital Library

【 摘 要 】

Evaluation of the fabrication processes involved in the manufacture of waste containers is important as these processes can have an effect on the metallurgical structure of an alloy. Since material properties such as strength, toughness, aging kinetics and corrosion resistance are all dependent on the microstructure, it is important that prototypes be built and evaluated for processing effects on the performance of the material. Of particular importance are welds, which have an as-cast microstructure with chemical segregation and precipitation of complex phases resulting from the welding process. The work presented in this report focuses on the effects of processes such as solution annealing, stress mitigation, and welding on the kinetics of precipitation and corrosion properties. For a waste package lifetime of thousands of years, it is impossible to test directly in the laboratory the behavior of Alloy 22 under expected repository conditions. The changes that may occur in these materials must be accelerated. For phase-stability studies this is achieved by accelerating the phase transformations by increasing test temperatures above those anticipated in the proposed repository. For these reasons, Alloy 22 characterization specimens are currently being aged at Lawrence Livermore National Laboratory (LLNL) Aging Facilities for times from 1 hour to 20 years at temperatures ranging from 200-750 C. These data as well as the data from specimens aged at 260 C, 343 C, and 427 C for 100,000 hours at Haynes International will be used for performance confirmation.