Effects of strain rate on strain-induced martensite nucleation and growth in 301LN metastable austenitic steel

Lalit Pun, Guilherme Corrêa Soares, Matti Isakov, Mikko Hokka

Tutkimustuotos: ArtikkeliScientificvertaisarvioitu

6 Lataukset (Pure)

Abstrakti

The effects of strain rate on strain-induced α′-martensite nucleation and growth were analyzed in this work. Tension tests were performed at room temperature at strain rates of 2×10−4 s−1 and 0.5 s−1 using small polished specimens that fit inside a scanning electron microscope. The specimens were deformed incrementally, and microstructural evolution was tracked carefully at a specific location on the specimen surface. This approach allows the analysis not only of the spatial but also of the temporal evolution of the α′-martensite. Optical microscopy images and electron backscatter diffraction (EBSD) measurements were taken for each plastic deformation increment. The size and number of α′-martensite particles were evaluated from the EBSD images, whereas local microlevel strains were obtained using Digital Image Correlation (DIC). According to the results, the number of nucleation sites for α′-martensite does not seem to be affected much by the strain rate. However, there is a notable strain rate effect on how the transformation proceeds in the neighborhood of freshly formed α′-martensite particles. At a low strain rate, repeated nucleation and coalescence leads to the notable growth of α′-martensite particles, whereas at a high strain rate, once nucleated α′-martensite particles remain as small isolated islands that do not markedly grow with further plastic strain. This phenomenon can be attributed to local microstructure-level heating caused by plastic deformation and exothermic phase transformation. This reduces the local growth rate of the α′-martensite particles in the vicinity of the above-mentioned islands, thus leading to a lower bulk transformation rate at higher strain rates.

AlkuperäiskieliEnglanti
Artikkeli142218
Sivumäärä10
JulkaisuMaterials Science and Engineering A
Vuosikerta831
Varhainen verkossa julkaisun päivämäärä20 lokak. 2021
DOI - pysyväislinkit
TilaJulkaistu - 13 tammik. 2022
OKM-julkaisutyyppiA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Julkaisufoorumi-taso

  • Jufo-taso 2

!!ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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