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On the microstructure and mechanical properties of an Fe-10Ni-7Mn martensitic steel processed by high-pressure torsion

On the microstructure and mechanical properties of an Fe-10Ni-7Mn martensitic steel processed by high-pressure torsion
On the microstructure and mechanical properties of an Fe-10Ni-7Mn martensitic steel processed by high-pressure torsion
High-pressure torsion (HPT) processing was applied to an Fe-10Ni-7Mn (wt.%) martensitic steel at room temperature and the grain size was reduced from an initial value of ~5.5 μm to an ultrafine value of ~185 nm for the ferritic phase and around 30 nm for the austenitic phase after 20 HPT turns. The microstructure and mechanical properties of the as-processed material were evaluated using X-ray diffraction (XRD), electron backscatter diffraction (EBSD), field emission scanning electron microscopy (FESEM), microhardness measurements and tensile testing. In addition, annealing of an as-processed specimen was analyzed by differential scanning calorimetry (DSC). The results show that HPT processing increases the hardness and ultimate tensile strength to ~690 Hv and ~2230 MPa, respectively, but the ductility is decreased from ~16.5% initially to ~6.4% and ~3.1% after 10 and 20 turns, respectively. The hardness distributions and EBSD images show that a reasonably homogeneous microstructure is formed when applying a sufficient level of pressure and torsional strain. The DSC results demonstrate that processing by HPT reduces the start and finish temperatures of the reverse transformation of martensite to austenite and there is continuous re-crystallization after the recovery process.
0921-5093
27-34
Kalahroudi, Faezeh J.
e95ed223-6ad2-473a-9811-4dd1484edf63
Koohdar, Hamidreza
9f91e15b-f2b5-4226-a5fc-4f1d58f18773
Jafarian, Hamidreza
a591aa73-c29d-4451-a588-512e165620ff
Huang, Yi
9f4df815-51c1-4ee8-ad63-a92bf997103e
Langdon, Terence G.
86e69b4f-e16d-4830-bf8a-5a9c11f0de86
Nili-Ahmadabadi, Mahmoud
74c5b0be-a73e-40fe-bc6e-8450bc0eeaf7
Kalahroudi, Faezeh J.
e95ed223-6ad2-473a-9811-4dd1484edf63
Koohdar, Hamidreza
9f91e15b-f2b5-4226-a5fc-4f1d58f18773
Jafarian, Hamidreza
a591aa73-c29d-4451-a588-512e165620ff
Huang, Yi
9f4df815-51c1-4ee8-ad63-a92bf997103e
Langdon, Terence G.
86e69b4f-e16d-4830-bf8a-5a9c11f0de86
Nili-Ahmadabadi, Mahmoud
74c5b0be-a73e-40fe-bc6e-8450bc0eeaf7

Kalahroudi, Faezeh J., Koohdar, Hamidreza, Jafarian, Hamidreza, Huang, Yi, Langdon, Terence G. and Nili-Ahmadabadi, Mahmoud (2019) On the microstructure and mechanical properties of an Fe-10Ni-7Mn martensitic steel processed by high-pressure torsion. Materials Science and Engineering: A, 749, 27-34. (doi:10.1016/j.msea.2019.02.002).

Record type: Article

Abstract

High-pressure torsion (HPT) processing was applied to an Fe-10Ni-7Mn (wt.%) martensitic steel at room temperature and the grain size was reduced from an initial value of ~5.5 μm to an ultrafine value of ~185 nm for the ferritic phase and around 30 nm for the austenitic phase after 20 HPT turns. The microstructure and mechanical properties of the as-processed material were evaluated using X-ray diffraction (XRD), electron backscatter diffraction (EBSD), field emission scanning electron microscopy (FESEM), microhardness measurements and tensile testing. In addition, annealing of an as-processed specimen was analyzed by differential scanning calorimetry (DSC). The results show that HPT processing increases the hardness and ultimate tensile strength to ~690 Hv and ~2230 MPa, respectively, but the ductility is decreased from ~16.5% initially to ~6.4% and ~3.1% after 10 and 20 turns, respectively. The hardness distributions and EBSD images show that a reasonably homogeneous microstructure is formed when applying a sufficient level of pressure and torsional strain. The DSC results demonstrate that processing by HPT reduces the start and finish temperatures of the reverse transformation of martensite to austenite and there is continuous re-crystallization after the recovery process.

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Kalahroudi-MSE 2019_accepted manuscript - Accepted Manuscript
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Accepted/In Press date: 1 February 2019
e-pub ahead of print date: 2 February 2019
Published date: 11 March 2019

Identifiers

Local EPrints ID: 428247
URI: https://eprints.soton.ac.uk/id/eprint/428247
ISSN: 0921-5093
PURE UUID: b0b9749a-f2a8-4609-867e-d22835f2bb2f
ORCID for Yi Huang: ORCID iD orcid.org/0000-0001-9259-8123
ORCID for Terence G. Langdon: ORCID iD orcid.org/0000-0003-3541-9250

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Date deposited: 18 Feb 2019 17:30
Last modified: 14 Mar 2019 01:45

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Contributors

Author: Faezeh J. Kalahroudi
Author: Hamidreza Koohdar
Author: Hamidreza Jafarian
Author: Yi Huang ORCID iD
Author: Mahmoud Nili-Ahmadabadi

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