| 1. |
- Bate, Pete, et al.
(författare)
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Application of laser-ultrasonics to texture measurements in metal processing
- 2017
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Ingår i: Acta Materialia. - : Elsevier BV. - 1359-6454 .- 1873-2453. ; 123, s. 329-336
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Tidskriftsartikel (refereegranskat)abstract
- The paper describes in principle how information about textures can be obtained through the application of laser-ultrasonics (LUS) which can be carried out at elevated temperatures, for example in connection with hot rolling. The benefits from getting a measure of texture in this way are explained together with the proposed methodology which is based on the elastic anisotropic properties of the textured material. Measurements are made using only a single laser pulse and in real-time. Two approaches are presented to modelling the propagation of elastic waves, ray tracing and finite difference modelling. These give consistent results but the latter provides a more complete prediction of the ultrasonic spectrum that can be quantitatively related to measured signals through a cross-correlation procedure. Some experimental results are presented for room temperature measurements on a sheet of interstitial-free steel. Agreement between experimental data and modelling results is good and allows estimation of the 4th order coefficients of the orientation distribution function.
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| 2. |
- Hutchinson, Bevis, et al.
(författare)
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Elasticity and wave velocity in fcc iron (austenite) at elevated temperatures – Experimental verification of ab-initio calculations
- 2018
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Ingår i: Ultrasonics. - : Elsevier. - 0041-624X .- 1874-9968. ; 87, s. 44-47
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Tidskriftsartikel (refereegranskat)abstract
- High temperature crystal elasticity constants for face centred cubic austenite are important for interpreting the ultrasonic properties of iron and steels but cannot be determined by normal single crystal methods. Values of these constants have recently been calculated using an ab-initio approach and the present work was carried out to test their applicability using laser-ultrasonic measurements. Steel samples having a known texture were examined at temperatures between 800 °C and 1100 °C to measure the velocity of longitudinal P-waves which were found to be in good agreement with modelled values.
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| 3. |
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| 4. |
- Hutchinson, Bevis, et al.
(författare)
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Plastic yielding in lath martensites – An alternative viewpoint
- 2018
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Ingår i: Acta Materialia. - : Elsevier BV. - 1359-6454 .- 1873-2453. ; 152, s. 239-247
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Tidskriftsartikel (refereegranskat)abstract
- In recent literature the gradual yielding of quenched martensitic steels has been attributed to either heterogeneous microstructures having different strength levels or to the presence of small scale, Type II, residual stresses. Using in-situ tensile testing in synchrotron diffraction experiments in combination with crystal plasticity finite element modelling (CPFEM) we show that the dominant influence on yielding derives from the residual stresses which are a product of the displacive transformation from austenite during quenching. As plastic straining proceeds, the measured diffraction peaks become narrower and asymmetric, as predicted by the CPFEM calculations. The model predictions are generally in good agreement with published results showing large variations in local strains in different microstructural elements.
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| 5. |
- Mauritzson, Lena, et al.
(författare)
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Texture studies using laser ultrasonics (LUS) in metal processing
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The results and modelling analyses presented here showsthat laser-ultrasonics (LUS) provide a viable method for obtaining texture informationin metal sheets. LUSwhich can be carried out at elevated temperatures, and are suitablefor measurementsin connection withhot processing of steels and other metals. Two approaches are presented to modelling the propagation of elastic waves, ray tracing and finite difference modelling. These give consistent results but the latter provides a more complete prediction of the ultrasonic spectrum that can be quantitatively related to measured signals through a cross-correlation procedure.There is good reason to believe thatthis method enable in-line process controloftextures.
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