Observations of ``1000{degree}F embrittlement`` in Ni-base superalloys
- General Electric Corporate Research and Development, Schenectady, NY (United States)
In this study, the effect of cold work and ``low temperature`` thermal exposure on tensile behavior was evaluated. Superalloys Rene 88DT and IN718 were compressed at room temperature to induce cold work in excess of what could be achieved in tension. Tensile tests were performed on the compressed material after subsequent heat treatments. A dramatic increase in strength and significant loss in ductility was observed for material that was compressed 30%, exposed to 538 C and tensile tested at room temperature (compared to as-compressed material). The effect was less dramatic at lower levels of cold work, and subsequent high temperature heat treatments were shown to restore ductility and decrease strength. The mechanism for this 1,000 F embrittlement of highly deformed superalloys is still not known. Environmental embrittlement can be ruled out, since the vacuum results are the same as the air results. It is unlikely that this is the result of precipitation of a phase (carbides or other) on dislocations, since no differences were observed in the exposed and unexposed thin foil and extraction replica samples in TEM. Work is currently underway to investigate a possible role of solute atoms. The data presented here are not inconsistent with strain aging phenomena.
- OSTI ID:
- 233902
- Journal Information:
- Scripta Materialia, Vol. 34, Issue 9; Other Information: PBD: 1 May 1996
- Country of Publication:
- United States
- Language:
- English
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