Tensile deformation behavior in metastable austenitic stainless steel having ultra fine grain structure

Kouki Tomimura, Hiroki Nagamori, Setsuo Takaki, Youichi Tokunaga

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Deformation behavior in metastable austenitic stainless steel having an ultra fine grain structure has been investigated using a 12.5%Cr-9.5%Ni-2%Mo-0.1%N steel by means of a tensile test with particular emphasis on the behavior of deformation induced martensite (α′). The ultra fine grain austenite (γ) structure was achieved by reversion from α′ to γ. The grain size was controlled in the range between 0.2 and 40 μm by selecting annealing temperatures from 950 to 1400 K. Nominal stress-strain curves of the ultra fine grain (≤0.5 μm) specimens, which were obtained by annealing at temperatures from 973 to 1023 K for 180 s, exhibit the upper and lower yield points followed by a constant stress level between them (yield point phenomena). At the plateau stage neck is locally introduced and propagated in the gage position by heterogeneous deformation, accompanied by α′ formation. The occurrence of the yield point phenomenon and the size of the neck depend on two true stresses, i.e. the work hardening stress especially by the formation of α′ (σR) and the concentrated stress by the reduction of area (σL) in the necked area. The heterogeneous deformation in the ultra fine grain specimens can be explained by the plastic instability, that is, σL is higher than σR, which arises from the fact that α′ formation is largely suppressed by the grain refinement. When σR is higher than σL as in the case of coarser grain specimens, local necking is arrested and the deformation is propagated to another position, leading to uniform deformation.

Original languageEnglish
Pages (from-to)376-382
Number of pages7
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume55
Issue number4
DOIs
Publication statusPublished - Jan 1 1991

Fingerprint

tensile deformation
austenitic stainless steels
Crystal microstructure
Austenitic stainless steel
yield point
Annealing
annealing
work hardening
Steel
Grain refinement
Stress-strain curves
tensile tests
austenite
martensite
Strain hardening
Martensite
Austenite
Gages
plateaus
plastics

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

Cite this

Tensile deformation behavior in metastable austenitic stainless steel having ultra fine grain structure. / Tomimura, Kouki; Nagamori, Hiroki; Takaki, Setsuo; Tokunaga, Youichi.

In: Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals, Vol. 55, No. 4, 01.01.1991, p. 376-382.

Research output: Contribution to journalArticle

Tomimura, Kouki ; Nagamori, Hiroki ; Takaki, Setsuo ; Tokunaga, Youichi. / Tensile deformation behavior in metastable austenitic stainless steel having ultra fine grain structure. In: Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals. 1991 ; Vol. 55, No. 4. pp. 376-382.
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