Effect of Pre-cold-working on Diffusional Reversion of Deformation Induced Martensite in Metastable Austenitic Stainless Steel

Setsuo Takaki

Research output: Contribution to journalArticle

93 Citations (Scopus)

Abstract

Metastable austenitic stainless steels undergo deformation induced transformation to bcc martensitic structure during cold-working. The martensite induced reverts to austenite at a relatively low temperature and this leads to the formation of ultra fine austenite grains of less than 1 μm in diameter. In this paper, the effect of pre-cold-working on the morphology of reversed austenite was investigated by means of transmission electron microscopy and tensile test. The alloy used is an Fe-18.08%Cr-8.65%Ni alloy. Since this alloy has metastable austenitic structure at room temperature, it almost transforms to lath-martensite by 50% cold-rolling. Further cold-rolling above 50% deforms transformed martensite itself, and results in the formation of dislocation-cell structure instead of lath-martensitic structure. The diffusional reversion of deformation induced martensite takes place at around 900 K and pre-cold-working to lath-martensite not only promotes the reversion but also gives a large effect on the microstructure of reversed austenite: Reversed austenite is characterized, in a specimen with 50% pre-cold-working, by the stratum structure of austenite laths and blocks, which looks like a lath-martensitic structure, while in a specimen with heavy pre-cold-working, by the structure of fine equiaxed grains. On the discussion of grain boundary strengthening in the former case, 0.2% proof stress depends not on the lath size but on the block size of reversed austenite.

Original languageEnglish
Pages (from-to)522-527
Number of pages6
Journalisij international
Volume34
Issue number6
DOIs
Publication statusPublished - Jan 1 1994

Fingerprint

Cold working
Austenitic stainless steel
Martensite
Austenite
Cold rolling
Grain boundaries
Transmission electron microscopy
Temperature
Microstructure

All Science Journal Classification (ASJC) codes

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

Cite this

Effect of Pre-cold-working on Diffusional Reversion of Deformation Induced Martensite in Metastable Austenitic Stainless Steel. / Takaki, Setsuo.

In: isij international, Vol. 34, No. 6, 01.01.1994, p. 522-527.

Research output: Contribution to journalArticle

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abstract = "Metastable austenitic stainless steels undergo deformation induced transformation to bcc martensitic structure during cold-working. The martensite induced reverts to austenite at a relatively low temperature and this leads to the formation of ultra fine austenite grains of less than 1 μm in diameter. In this paper, the effect of pre-cold-working on the morphology of reversed austenite was investigated by means of transmission electron microscopy and tensile test. The alloy used is an Fe-18.08{\%}Cr-8.65{\%}Ni alloy. Since this alloy has metastable austenitic structure at room temperature, it almost transforms to lath-martensite by 50{\%} cold-rolling. Further cold-rolling above 50{\%} deforms transformed martensite itself, and results in the formation of dislocation-cell structure instead of lath-martensitic structure. The diffusional reversion of deformation induced martensite takes place at around 900 K and pre-cold-working to lath-martensite not only promotes the reversion but also gives a large effect on the microstructure of reversed austenite: Reversed austenite is characterized, in a specimen with 50{\%} pre-cold-working, by the stratum structure of austenite laths and blocks, which looks like a lath-martensitic structure, while in a specimen with heavy pre-cold-working, by the structure of fine equiaxed grains. On the discussion of grain boundary strengthening in the former case, 0.2{\%} proof stress depends not on the lath size but on the block size of reversed austenite.",
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