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Title: Effects of minor alloying additions on the strength and swelling behavior of an austenitic stainless steel. [4 MeV nickel ions]

Technical Report ·
DOI:https://doi.org/10.2172/6670466· OSTI ID:6670466

A set of 32 alloys consisting of various additions of the elements Mo, W, Al, Ti, Nb, C and Si to an Fe-7.5 Cr-20 Ni alloy were made in order to investigate the effects of these solute additions on alloy swelling and strength. Both single and multiple additions were examined. The influence of various solute elements on the swelling behavior in the range 500 to 730/sup 0/C was investigated using 4 MeV Ni ion bombardment to a dose 170 dpa. It was found that on an atomic percent basis, the elements may be arranged in order of decreasing effectiveness in reducing peak temperature swelling as follows: Ti, C, Nb, Si, and Mo. Small amounts of aluminum enhance swelling. Additions of Si, Ti, or Nb truncate the high temperature swelling regime of the ternary alloy. Mo, W, and C do not have a strong effect on the temperature dependence of swelling. The results may be interpreted in terms of the effect of point defect trapping on void growth rates, and it is suggested that the changes in peak temperature are the result of small changes in the free vacancy formation energy. A method for treating certain multiple additions is proposed. The effect of these alloying additions on short time high temperature strength properties was estimated using hot hardness measurements over the temperature range 22 to 850/sup 0/C. On an atom percent basis Nb and Ti were most effective in conferring solid solution strengthening and Si the least effective. In the regime 22 to approximately 650/sup 0/C, the hardness data was found to fit an equation of the form: H = H/sub 0/ + b/T; where H is the hardness, T is the temperature, and H/sub 0/ and b are constants for a given alloy. An empirical method was devised to estimate the hot hardness of alloys containing more than one solute addition.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
DOE Contract Number:
W-7405-ENG-26
OSTI ID:
6670466
Report Number(s):
ORNL/TM-6359; TRN: 78-018807
Resource Relation:
Other Information: Thesis. Submitted to Iowa State Univ
Country of Publication:
United States
Language:
English