Age Hardening of Binary Iron-Nickel Martensites.
Abstract
Age hardening of binary Fe-Ni martensites was investigated to determine the nature and kinetics of the hardening reaction. Six Fe-Ni alloys containing 24 to 34 wt% Ni were austenitized, quenched, then cooled to either 16 degrees C to retain austenite or to -196 degrees C to promote the transformation to martensite. Specimens were aged at six temperatures between 270 and 450 degrees C for up to 14,000 hr. Four other ferritic/martensitic alloys containing 5 to 30 wt% Ni, previously cold rolled and aged 8000 hr, were also aged. Specimens were studied by hardness and tensile testing, x-ray diffraction, electron microscopy, and Fe-57 Mossbauer spectroscopy. Age hardening occurred in all of the 24 to 34 wt% Ni martensites and at all of the aging temperatures. The maximum hardening of 270 HV (up to 480 HV) occurred in an Fe-32Ni martensite upon aging 8000 hr at 300 C. Hardening was attributed to Ni-rich, disc-shaped, austenite particles formed on (110) matrix planes during aging. The 30 to 34 wt% Ni alloys cooled to 16 C were largely austenite, very soft (100 HV), and not age harden. Keywords: Age hardening; Precipitation; Fe-Ni alloys.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1985
- Accession Number
- ADA161407
Entities
People
- J. T. Carter
- W. C. Leslie
- Zhang Guosheng
Organizations
- University of Michigan