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Title: The effects of heat treatment and environment on corrosion fatigue. Volume 1, Alloy X-750: Final report

Technical Report ·
OSTI ID:10167136
; ;  [1]
  1. Massachusetts Inst. of Tech., Cambridge, MA (United States)

Alloy X-750 is a nickel-base alloy used extensively in Light Water Reactor (LWR) nuclear power systems due to its excellent corrosion resistance and high temperature strength. In spite of alloy X-750`s exceptional high temperature properties, it has been found to be susceptible to environmentally assisted fatigue and stress corrosion cracking in relatively low temperature aqueous environments such as those that exist in LWR systems. In order to develop a better understanding of the role that microstructure plays in the fatigue behavior of alloy X-750, three thermal treatments were studied. The treatments used were as hot worked + : (1) 24 h at 885{degree}C + 20 h at 704{degree}C (AH), (2) lh at 982{degree}C + 20 h at 704{degree}C (BH), and (3) 1 h at 1093{degree}C + 20 h at 704{degree}C (HTH). Fatigue crack growth tests were conducted at frequencies of 0.1 and 10 Hz in the following aqueous environments: (1) high purity, air saturated water (8 ppM O{sub 2}) at 93{degree}C and 288{degree}C, (2) high purity, deoxygenated water (5 ppb O{sub 2}) at 93{degree}C, and (3) simulated BWR water chemistry with hydrogen additions at 288{degree}C. Crack growth rate data was collected at constant values of stress intensity factor range ({Delta}K). The results show that crack growth rates and morphology are a function of {Delta}K, frequency, thermal treatment and environment. Frequency effects were most significant for the AH material. Crack growth rates generally decrease, for a given value of {Delta}K, in the BH and HTH materials with the HTH material showing the lowest growth rate.

Research Organization:
Electric Power Research Inst., Palo Alto, CA (United States); Massachusetts Inst. of Tech., Cambridge, MA (United States)
Sponsoring Organization:
Electric Power Research Inst., Palo Alto, CA (United States)
OSTI ID:
10167136
Report Number(s):
EPRI-TR-102436-Vol.1; ON: UN93015867; TRN: 93:020915
Resource Relation:
Other Information: PBD: May 1993
Country of Publication:
United States
Language:
English