In Situ X-Ray Diffraction during Casting: Study of Hot Tearing in Al-Zn Alloys

Abstract:

During solidification of metallic alloys, coalescence corresponds to the formation of solid bridges between grains when both solid and liquid phases are percolated. As such, it represents a key transition with respect to the mechanical behaviour of solidifying alloys and to the prediction of solidification cracking. Coalescence starts at the coherency point when the grains begin to touch each other, but are unable to sustain any tensile loads. It ends up at the rigidity temperature when the solid phase is sufficiently coalesced to transmit macroscopic tensile strains and stresses. This temperature, also called mechanical or tensile coherency temperature, is a major input parameter in numerical modelling of solidification processes as it defines the point at which thermally induced deformations start to generate internal stresses in a casting. The rigidity temperature has been determined in Al Zn alloys using in situ X-ray diffraction (XRD) during casting in a dog bone shaped mould. This set-up allows the sample to build up internal stress naturally as its contraction is prevented. The cooling on both extremities of the mould induces a hot spot at the middle of the sample which is irradiated by X-rays. Diffraction patterns were recorded every 0.5 s using a detector covering a 426 x 426 mm² area. The change of diffraction angles allowed us to observe agglomeration/decohesion of growing grain clusters and to determine a solid volume fraction at rigidity around 98 % depending on solidification time for grain refined Al 6.2 wt% Zn alloys.

• Periodical: Advanced Materials Research (Volumes 1120-1121)
• Pages: 1134-1141
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1120-1121.1134
• Online since: July 2015
• Authors: Jean Marie Drezet*, Bastien Mireux, Guven Kurtuldu
• Keywords: Aluminium Alloy, In Situ X-Ray Diffraction (XRD), Rigidity Temperature, Solidification

References

[1] Danzig, J.A.; Rappaz, M. Solidification, Defects; EPFL Press: Lausanne, Switzerland, (2009).

[2] Rappaz, M.; Jacot, A.; Boettinger, W.J., Met. Mat. Trans. A 2003, 34, 467–479.

[3] Rappaz, M.; Drezet, J. -M.; Gremaud, Met. Mat. Trans. A 1999, 30, 449–455.

[4] Stangeland, A.; Mo, A.; M'Hamdi, M.; Viano, D. and Davidson, Met. Mat. Trans. A 2006, 37, 705–714.

[5] Terzi, S.; Salvo, L.; Suery, M.; Limodin, N.; Adrien, J.; Maire, E.; Pannier, Y.; Bornert, M.; Bernard, D. and Felberbaum, M.; Scripta Mater. 2009, 61, 449–452.

DOI: 10.1016/j.scriptamat.2009.04.041

[6] Suéry, M.; Terzi, S.; Mireux, B.; Salvo, L.; Adrien, J.; Maire, E. Fast, JOM 2012, 64, 83–88.

DOI: 10.1007/s11837-011-0219-7

[7] Phillion, A.B.; Hamilton, R.W.; Fuloria, D.; Leung, A.C.L.; Rockett P., Connolley, T.; Lee, P.D., Acta Mater. 2011, 59, 1436–1444.

DOI: 10.1016/j.actamat.2010.11.005

[8] Gourlay, C.M.; Dahle, A.K.; Nagira, T.; Nakatsuka, N.; Nogita, K.; Uesugi, K.; Yasuda, H., Acta Mater. 2011, 59, 4933–4943.

DOI: 10.1016/j.actamat.2011.04.038

[9] Giraud, E.; Suéry, M.; Coret, M., Met. Mat. Trans. A 2010, 41, 2257–2268.

[10] Limodin N., L. Salvo, E. Boller, M. Suéry, M. Felberbaum, S. Gailliègue, K. Madi, Acta Materialia 57 (2009) 2300–2310.

DOI: 10.1016/j.actamat.2009.01.035

[11] Terzi S., J.A. Taylor, Y.H. Cho, L. Salvo, M. Suéry, E. Boller, A.K. Dahle, Acta Materialia 58 (2010) 5370–5380.

DOI: 10.1016/j.actamat.2010.06.012

[12] Drezet, J. -M.; Evans, A.; Pirling, T.; Pitié, B., Int. J. Cast Met. 2012, 25, 110–116.

[13] Drezet, J. -M., Pirling, T., J. Mater. Process. Technol. 214 (2014), 1372-1378.

[14] Chobaut N., Repper J., Pirling T., Carron D. and Drezet J-M.: Residual stress analysis in AA7449 as-quenched thick plates using neutrons and FE modelling, 13th International Conference on Aluminum Alloys (ICAA13), Edited by: Hasso Weiland, Anthony D. Rollett, William A. Cassada, TMS (The Minerals, Metals & Materials Society), 2012, 285-291.

DOI: 10.1002/9781118495292.ch44

[15] Chobaut N.; Michel, G., Saelzle P., Carron D., Drezet J. -M., Quench induced stresses in AA2618 forgings for impellers: a multi-physics and multi-scale problem, submitted to Journal of Metals, TMS, August (2015).

DOI: 10.1007/s11837-015-1363-2

[16] Drezet J. -M., Mireux B., Szaraz Z., Pirling T.: In situ Neutron Diffraction during Casting: Determination of Rigidity Point in Grain Refined Al-Cu Alloys. Materials 2014, 7, 1165-1172, http: /www. mdpi. com/1996-1944/7/2/1165.

DOI: 10.3390/ma7021165

[17] Diamond Light Source, Oxfordshire, UK, JEEP web site http: /www. diamond. ac. uk/Beamlines/Engineering-and-Environment/I12. html.

[18] Lalpoor, M., Eskin D.G., Katgermann, L., Met. Mater. Trans. A 2009, 40, 3304-3313.

[19] Alloy phase diagrams, ASM handbook, vol. 3, ASM, (1992).

[20] Drezet, J. -M, Mireux B, Magdysyuk O. and Drakopoulos M., submitted to Met. Mater. Trans. A.

[21] Le Bail, A., Duroy, H. and Fourquet, J. L. (1988). Mater. Res. Bull. 23, 447±452.

[22] Vernède S., Jarry P., Rappaz, M., Acta Mater. 2006, 54, 4023–4034.

[23] Sistaninia, M.; Phillion, A.B.; Drezet, J. -M.; Rappaz, M.,. Acta Mater. 2012, 60, 3902–3911.

DOI: 10.1016/j.actamat.2012.03.036

[24] Li S., Sadayappan K. and Apelian D., Int. J. of Cast Metals Research, vol. 24 (2), 2011, pp.88-95.