A B C Fig. 16 —Microstructures in the HAZ of the bead cross section produced by PTAWS. Current = 130 A without separation. A — Coarse grains; B — fine grains in Zone I; C — Zone II contains both coarse grains and fine grains. A B C Fig. 17 — Microstructures in the HAZ of the bead cross section produced by SPTAWS. Total current = 130 A with 40 A separation of the electron flow. A — Coarse grains; B — fine grains in Zone I; C — Zone II contains both coarse grains and fine grains. crostructure of the bead cross sections was investigated. For conventional PTAWS, increasing the current from 110 to 150 A expanded the HAZ. For SPTAWS, the HAZ decreased as the separated electron flow increased. According to microstructure analysis, it was found that the SPTAWS produced beads with finer and more uniform grains than the conventional PTAWS, especially in the fine-grain zone, because of the effect from the separated electron flow. This work is supported financially by the National Science and Technology Major Project of China (Grant No. 2014ZX04001171) and National Natural Science Foundation of China (Grant No.51375021) and the Project was supported by Beijing Postdoctoral Research Foundation (Grant No. 2015zz-15) and by the Chaoyang District Postdoctoral Research Foundation (Grant No.2014zz-02). 1. Menschutkin, B. N. 1936. Vasilij Vladimirovic Petrov and his physico-chemical work. The History of Science Society 25(2): 391–398. 2. Sanders, N., Etemadi, K., Hsu, K. C., and Pfender, E. 1982. Studies of the anode region of a high-intensity argon arc. Journa1 of Applied Physics 53(6): 4136–4145. 3. Welding Handbook. 9th Ed. Vol. 2, Welding Processes. 2004. Ed. A. O'Brien. Miami, Fla.: American Welding Society. 4. ASM Handbook. 10th Ed. Vol. 5, Surface Engineering. 1994. Ed. Catherine M. Cotell, James A. Sprague, and Fred A. Smidt, Jr. Materials Park, Ohio: ASM International. 5. Saltzman, G. A., and Sahoo, P. 1991. Applications of plasma arc weld surfacing in turbine engines. Proceedings of the Fourth National Thermal Spray Conference, Pittsburgh, Pa., pp. 541–548. 6. Hallen, H, Mathesms, H., Ait- Mekideche, A., Hettiger, F., Morkramer, U., and Lugscheider, E. 1992. New applications for high power PTA surfacing in the steel industry. Proceedings of the Conference of the International Thermal Spray, Orlando, Fla., pp. 899–902. 7. Edrisy, A., Perry, T, Cheng, Y. T., et al. 2001. Wear of thermal spray deposited lowcarbon steel coatings on aluminum alloys. 13th International Conference on Wear of Materials, WELDING RESEARCH Vancouver, Canada, 251: 1023–1033. 8. Schramm, L., Schwenk, A., and Hauser, E. 2012. Plasma transfer wire arc thermal spray system. Pub. No. US 2012/0018407 Al. 9. Shaw, C. B. 1980. Effect of orifice geometry in plasma arc welding of Ti-6Al-4 V. Welding Journal 59(4): 121–125. 10. The Physics of Welding. 2nd Ed. 1986. Ed. J. F. Lancaster. Pergamon Press. 11. Recommended Practices for Plasma Arc Welding. C5.l-73. 1973. Ed. Jay Bland. Miami, Fla.: American Welding Society. 12. Irving, B. 1997. Why aren't airplanes welded? Welding Journal 76(1): 31–41. 13. Nunes, A. C., Bayless, E. 0 ., and Jones, C. S. III, et al. 1984. Variable polarity plasma arc welding on the space shuttle external tank. Welding Journal 63(9): 27–35. 14. Irving, B. 1992. Plasma arc welding takes on the advanced solid rocket motor. Welding Journal 71(12): 49–50. 15. Liu, Y. F., Xia, Z. Y., Han, J. M., et al. 2006. Microstructure and wear behavior of (Cr, Fe)7C3 reinforced composite coating produced by plasma transferred arc weldsurfacing process. Surf Coat. Technol. 201(3–4): 863–867. 16. Su, C., Chou, C., Wu, B., and Lih, W. 1997. Plasma transferred arc repair welding of the nickel-base superalloy IN-738LC. JUNE 2016 / WELDING JOURNAL 227-s Acknowledgments References
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