| 1. |
- Hedström, Peter, et al.
(author)
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Elastic strain evolution and ε-martensite formation in individual austenite grains during in situ loading of a metastable stainless steel
- 2008
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In: Materials letters (General ed.). - : Elsevier BV. - 0167-577X .- 1873-4979. ; 62:2, s. 338-340
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Journal article (peer-reviewed)abstract
- The (hcp) ε-martensite formation and the elastic strain evolution of individual (fcc) austenite grains in metastable austenitic stainless steel AISI 301 has been investigated during in situ tensile loading up to 5% applied strain. The experiment was conducted using high-energy X-rays and the 3DXRD technique, enabling studies of individual grains embedded in the bulk of the steel. Out of the 47 probed austenite grains, one could be coupled with the formation of ε-martensite, using the reported orientation relationship between the two phases. The formation of ε-martensite occurred in the austenite grain with the highest Schmid factor for the active {111}b12¯1N slip system.
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| 2. |
- Hedström, Peter, et al.
(author)
-
Evolution of residual strains in metastable austenitic stainless steels and the accompanying strain induced martensitic transformation
- 2006
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In: Residual Stresses VII. - Uetikon-Zuerich : Trans Tech Publications Inc.. - 0878494146 ; 524-525, s. 818-826
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Conference paper (peer-reviewed)abstract
- The deformation behavior of metastable austenitic stainless steel AISI 301, suffering different initial cold rolling reduction, has been investigated during uniaxial tensile loading. In situ highenergy x-ray diffraction was employed to characterize the residual strain evolution and the strain induced martensitic transformation. Moreover, the 3DXRD technique was employed to characterize the deformation behavior of individual austenite grains during elastic and early plastic deformation. The cold rolling reduction was found to induce compressive residual strains in the austenite along rolling direction and balancing tensile residual strains in the -martensite. The opposite residual strain state was found in the transverse direction. The residual strain states of five individual austenite grains in the bulk of a sample suffering 2% cold rolling reduction was found to be divergent. The difference among the grains, considering both the residual strains and the evolution of these, could not be solely explained by elastic and plastic anisotropy. The strain states of the five austenite grains are also a consequence of the local neighborhood. Introduction The metastable austenitic stainless steels partially transform from the soft and ductile austenite to the hard and brittle martensite during deformation. This deformation induced martensitic transformation provides a compos...
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| 3. |
- Hedström, Peter, et al.
(author)
-
Stepwise transformation behavior of the strain-induced martensitic transformation in a metastable stainless steel
- 2007
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In: Scripta Materialia. - : Elsevier BV. - 1359-6462 .- 1872-8456. ; 56:3, s. 213-216
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Journal article (peer-reviewed)abstract
- In situ high-energy X-ray diffraction during tensile loading has been used to investigate the evolution of lattice strains and the accompanying strain-induced martensitic transformation in cold-rolled sheets of a metastable stainless steel. At high applied strains the transformation to α-martensite occurs in stepwise bursts. These stepwise transformation events are correlated with stepwise increased lattice strains and peak broadening in the austenite phase. The stepwise transformation arises from growth of α-martensite embryos by autocatalytic transformation.
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| 4. |
- Peng, Ru, 1960-, et al.
(author)
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Residual stress analysis in both As-deposited and annealed CrN coatings
- 2005
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In: Residual Stresses VII. - Uetikon-Zürich : Trans Tech Publications Inc.. - 0878499695 ; 490-491, s. 643-648
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Conference paper (peer-reviewed)abstract
- In this paper, we report on residual stress analysis in physical vapour deposited (PVD) CrN coatings. Two 9 μm thick coatings were grown on tool steel substrates with bias voltages of-50 V and -300 V, respectively. High-energy (E=80 keV) synchrotron radiation measurements have been performed to investigate residual stresses in both as-deposited and annealed CrN coatings. To understand the origins of non-linear distribution of lattice strain versus sin2Ψ for certain (hkl) planes in both coatings, a stress orientation distribution function (SODF) analysis has been carried out, which yields grain-orientation-dependent residual stresses. The results are compared to previous analyses using Reuss and Vook-Witt models on the as-deposited coatings.
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| 5. |
- Terner, Mark, et al.
(author)
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Residual stress evolution during decomposition of Ti(1-x)Al (x)N coatings using high-energy x-rays
- 2006
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In: RESIDUAL STRESSES VII. - : Transtec Publications; 1999. ; 524-525, s. 619-624, s. 619-624
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Conference paper (peer-reviewed)abstract
- Residual stresses and microstructural changes during phase separation in Ti33Al67N coatings were examined using microfocused high energy x-rays from a synchrotron source. The transmission geometry allowed simultaneous acquisition of x-ray diffraction data over 360 degrees and revealed that the decomposition at elevated temperatures occurred anisotropically, initiating preferentially along the film plane. The as-deposited compressive residual stress in the film plane first relaxed with annealing, before dramatically increasing concurrently with the initial stage of phase separation where metastable, nm-scale c-AlN platelets precipitated along the film direction. These findings were further supported from SAXS analyses.
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