Synchrotron Diffraction Studies on the Transformation Strain in a High Strength Quenched and Tempered Structural Steel

Abstract:

In-situ phase transformation behaviour of a high strength (830 MPa yield stress) quenched and tempered S690QL1 (Fe-0.16C-0.2Si-0.87Mn-0.33Cr-0.21Mo (wt. %)) structural steel, during continuous cooling under different mechanical loading conditions to promote the bainitic transformation, was studied. Time-temperature-load resolved 2D synchrotron diffraction patterns were recorded and used to calculate the transformation strains. The temperature dependent elastic constants of ferrite in the steel were also determined using \textit{in-situ} tensile tests at different temperatures in a synchrotron X-ray diffractometer. The transformation strains were calculated under different loading conditions.The elastic constants were calculated from the lattice parameters at 25 °C, 200 °C, 300 °C, 400 °C, 500 °C and 600 °C. The elastic constants varied from 202 GPa at 25 °C to 143 GPa at 600 °C. The variation in lattice plane strains during phase transformation under small external loads were calculated. Bulk measurement techniques such as dilatation experiments give the averaged transformation strains. However, in-situ synchrotron measurements performed in this work describe the transformation strains of the individual transforming phases and the strains arising due to possible variant selection.

• Periodical: Materials Science Forum (Volume 777)
• Pages: 231-236
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.777.231
• Online since: February 2014
• Authors: R.K. Dutta*, R.M. Huizenga, M. Amirthalingam, H. Gao, A. King, M.J.M. Hermans, I.M. Richardson
• Keywords: Bainitic Transformation, Steel, Thermomechanical Loading, Transformation Strain

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