VSMPO-AVISMA Corporation, Verkhnyaya Salda, Russia:

M. O. Leder, Science and Technology Director
A. V. Gorina, Second Category Research Engineer
M. A. Kornilova, First Category Research Engineer
E. N. Kondrashov, Consultant, e-mail: ken060776@rambler.ru

This article considers the method of definition of some thermal-physics properties of titanium alloys and boundary data parameters during vacuum arc remelting. This method is based on the modelling of the process of solidification and comparison of calculation results with experimentally measured liquid bath profiles in ingot. According to this, this method may be divided on experimental and calculation parts. Experimental part allows the definition of the liquid bath boundaries in solidified ingots in various moments of time without use of any markers. Generally, experimental part includes the ingot smelting, cutting out the diametric longitudinal template, its rolling, thermal treatment, mechanical processing, etching and measurement of the coordinates of liquid bath profiles, identified with liquidus isotherms. Calculation compound is based on solving the inverse thermal conductivity problem for solidified ingot. According to this, the rated coordinates of liquidus isotherm are calculated by mathematical model of vacuum arc remelting process. Unknown parameters in the mathematical model of solidification process are defined by the minimization of displacements of rated liquidus isotherm coordinates from the experimentally measured ones. The method defined the thermal-physics parameters of liquid phase, specific heat, thermal conductivity and specific melting heat. Coefficients of boundary data for vacuum arc remelting were also defined: maximal reheating under liquidus temperature and the parameter, defining the relative impact of radiation in common heat sink from ingot.

1. Mills K. C., Lee P. D. Thermophysical Property Requirements for Modelling of High Temperature Processes. 1st International Symposium on Microgravity Research and Applications in Physical Sciences and Biotechnology. European Space Agency. 2000. pp. 555–563.
2. Egry I., Holland-Moritz D., Novakovic R., Ricci E., Wunderlich R., Sobczak N. Thermophysical Properties of Liquid AlTi-Based Alloys. International Journal of Thermophysics. 2010. Vol. 31, No. 4/5. pp. 949–965.
3. Sanders P. G., Thompson M. O., Renk T. J., Aziz M. J. Liquid Titanium Solute Diffusion Measured by Pulsed Ion-Beam Melting. Metallurgical and Materials Transactions: A. 2001. Vol. 32. pp. 2969–2974.
4. Cai J., Yang Y., Liao L., Lyu G. Material Spectral Emissivity Measurement Based on Two Reference Blackbodies. International Journal of Thermophysics. September, 2015. pp. 1–9.
5. Monde M., Kosaka M., Mitsutake Y. Simple measurement of thermal diffusivity and thermal conductivity using inverse solution for one-dimensional heat conduction. International Journal of Heat and Mass Transfer. 2010. Vol. 53, No. 23/24. pp. 5343–5349.
6. Mills K. C. Recommended Values of Thermophysical Properties for Selected Commercial Alloys. Cambridge : Woodhead Publishing Limited, 2002. 246 p.
7. Boivineau M., Cagran C., Doytier D., Eyraud V., Nadal M.-H., Wilthan B., Pottlacher G. Thermophysical Properties of Solid and Liquid Ti – 6Al – 4V (TA6V) Alloy. International Journal of Thermophysics. 2006. Vol. 27, No. 2. pp. 507–529.
8. Veiga C., Davim J. P., Loureiro A. J. R. Properties and applications of titanium alloys. Reviews of Advanced Materials Science. 2012. Vol. 32. pp. 133–148.
9. Ou J., Cockcroft S. L., Maijer D. M., Yao L., Reilly C., Akhtar A. An examination of the factors influencing the melting of solid titanium in liquid titanium. International Journal of Heat and Mass Transfer. 2015. Vol. 86. pp. 221–233.
10. Singh B. P., Kumar J., Jha I. S., Adhikari D. Concentration Dependence of Thermodynamic Properties of NaPb Liquid Alloy. World Journal of Condensed Matter Physics. 2011. Vol. 1, No. 3. pp. 97–100.
11. Kondrashov E. N., Musatov M. I., Maksimov A. Yu., Goncharov A. E., Konovalov L. V. Calculation of the Molten Pool Depth in Vacuum Arc Remelting of Alloy VT3-1. Journal of Engineering Thermophysics. 2007. Vol. 16, No. 1. pp. 19–25.
12. Kondrashov E. N., Tarenkova N. Yu., Maksimov A. Yu., Fedorov N. S., Konovalov L. V. Korrektirovka znacheniy teplofizicheskikh svoystv titanovykh splavov iz analiza profiley zhidkoy vanny (Correction of indicators of thermalphysics properties of titanium alloys from liquid bath profile analysis). Tsvetnye Metally = Non-ferrous metals. 2008. No. 12. pp. 68–71.
13. Drezet J.-M., Rappaz M., Grün G.-U., Gremaud M. Determination of Thermophysical Properties and Boundary Conditions of Direct Chill-Cast Aluminum Alloys Using Inverse Methods. Metallurgical and Materials Transactions: A. 2000. Vol. 31. pp. 1627–1634.
14. James V. Beck, Ben Blackwell, Charles R. St. Clair, Jr. Nekorrektnye obratnye zadachi teploprovodnosti (Inverse Heat Conduction: Ill-Posed Problems). Moscow : Mir, 1989. 312 p.
15. Yaparova N. M. Chislennoe modelirovanie resheniy obratnoy granichnoy zadachi teploprovodnosti (Numerical modelling of the solutions of inverse boundary problem of heat conductivity). Vestnik Yuzhno-Ural'skogo gosudarstvennogo universiteta. Seriya “Matematicheskoe modelirovanie i programmirovanie» = Mathematical Modelling, Programming & Computer Software” of the South Ural State University Bulletin. 2013. Vol. 6, No. 3. pp. 112–124.
16. Kondrashov P. N., Kondrashov E. N. Konvektivnaya teploperedacha pri vakuumnom dugovom pereplave splava Ti – 6 Al – 4 V v atmosfere geliya (Heat convection during vacuum arc remelting of alloy Ti – 6 Al – 4 V in helium atmosphere). Elektrometallurgiya = Electrometallurgy. 2014. No. 8. pp. 31–35.