41
42
Figure 5-6 Relationship between ΔTi and welding current
43 용접변수에 따른 산화물 변화
용접 변수에 다라 TiO2의 용해된 정도를 확인하고자 Figure 5-5와 같이 용접전류에 따른 용접부에서 Ti의 함량을 조사하였다. A21와 C16의 경우 용접속도가 50cm/min으로 용접을 하였을 경우 A21 와 C16 에서 Ti 함량이 높아졌으며 용접속도가 60cm/min 으로 증가함에 따라 Ti 함량이 감소하였다. 반면 B18 의 경우 용접속도가 증가함에도 불구하고 용접부 내 Ti 함량이 거의 변하지 않았다. 선행연구에 따르면 Ti 함량이 증가함에 따라 산화물의 크기 및 분율은 증가함을 알 수 있으며[37-39] 이를 확인하기 위해 용접전류에 따른 산화물의 크기를 Figure 5-6 에 정리하였다. 결과 A21 과 C16 의 경우 용접속도가
50cm/min 일 때 보다 60cm/min 일 때 산화물의 크기가 현저하게 감소함을 확인하였다.
반면 B18 의 경우 용접속도에 따라 산화물의 크기가 크게 변하지 않는 것을 확인할 수 있었다.
44
Figure 5-7 Relationship between Ti contents in weld metal and welding current
Figure 5-8 Relationship between Oxide particle size and welding current
45
Figure 5-9 Effect of TiO2 composition and welding speed on penetration
46
6 결론
본 연구는 입열량에 영향을 미치는 용접조건 및 플럭스 조성에 따른 용입의 변화를 조사하였으며 결과는 다음과 같다.
1. Si, Al, Ti 는 Δ값이 양수로 나타났으며 인로인해 용융풀 내 산소함량이
증가하였으며 결과 마랑고니 효과로 인해 용입이 증가하였다.
2. ΔMn 은 음수로 나타났으며 음의 방향으로 증가함에 따라 ΔO 의 값이 증가하는 경향을 보였다. 하지만 플럭스 내 SiO2 의 함량이 증가함에 따라 용융된 슬래그 내 Mn의 활동도가 감소하였으며 ΔMn 은 음의 방향으로 증가하였다.
3. 용접변수 즉 용접전류나 용접속도를 조절하여 용입을 증가시키면 용입은 증가하였지만 플럭스에 TiO2 가 있을 경우 입열량이 감소함에 따라 용융되지 못한 TiO2 가 생길 수 있으며 용융된 용접부로 이동하는 Ti 의 함량이 감소함에 따라 TiO2가 적게 생길 수 있다.
47
참고문헌
1. Kou, S., WELDING METALLURGY. 2009: Wiley-Interscience.
2. Houldcroft, P.T., Submerged arc welding. 1990: Abington publishing.
3. S. Shen, I.N.A.O., S. Yannacopoulos, Effect of heat input on weld bead geometry of submerged arc welded ASTM A709 Grade 50 steel joints. Journal of Materials Processing Technology, 2012. 212(1): p. 286-294.
4. R.S. Chandel , H.P.S., F.L. Cheong, Effect of increasing deposition rate on the bead
geometry of submerged arc welds. Journal of Materials Processing Technolog, 1997. 72: p.
124-128.
5. B.G. Renwick, B.M.P., Operating characteristics of submerged arc process. weld.J., 1976. 55:
p. 69-79.
6. S.R. Gupta, N.A., Influence of flux basicity on weld bead geometry and HAZ in submerged arc welding. J. Mater. Process. Technol., 1993. 39: p. 33-42.
7. Chandel, R.S., Mathematical Modeling of Melting Rates for Submerged Arc Welding. Weld.
Res. Suppl., 1987.
8. Beomjoo Kim, S.U., Changhee Lee, Jongbong Lee, Youngho An, Effects of Inclusions and Microstructures on Impact Energy of High Heat-Input Submerged-Arc-Weld Metals.
Journal of Engineering Materials and Technology, 2005. 127(2): p. 204-213.
9. D.M. Viano, N.U.A.G.O.S., Influence of heat input and travel speed on microstructure and mechanical properties of double tandem submerged arc high strength low alloy steel weldments. Science and Technology of Welding and Joining, 2013. 5(1): p. 26-34.
10. P. A. BURCK, J.E.I.A.D.L.O., Effects of Welding Flux Additions on 4340 steel Weld Metal Composition. Welding Journal, 1990: p. 115-124.
11. CB Dallam, S.L., DL Olson, Flux composition dependence of microstructure and toughness of submerged arc HSLA weldments. WELDING JOURNAL, 1985: p. 140-152.
12. N.D. Pandey, A.B., Effect of submerged arc welding parameters and fluxes on element transfer behaviour and weld-metal chemistry Journal of Materials Processing Technology, 1994. 40: p. 195-211.
48
13. Jin Zhang, T.C., Cong Wang, Element Transfer Behaviors of Fused CaF2-SiO2 Fluxes Subject to High Heat Input Submerged Arc Welding. Metallurgical and Materials Transactions B, 2019. 51(1): p. 16-21.
14. KANJILAL, T.K.P., S. K. MAJUMDAR, Prediction of Element Transfer in Submerged Arc Welding. WELDING JOURNAL, 2007. 86: p. 135-146.
15. C. R. HEIPLE, J.R.R., Mechanism for Minor Element Effect on GTA Fusion Zone Geometry.
WELDING RESEARCH, 1982: p. 97-102.
16. LIMMANEEVICHITR, S.K., Visualization of Marangoni Convection in Simulated Weld Pools.
WELDING RESEARCH SUPPLEMENT, 2000: p. 126-135.
17. M.G. Velarde, R.K.Z., The Effect of Interfacial Phenomena on Materials Processing. 2002.
18. Richard French, H.M.-R., Will Yeadon, A Feasibility Study Comparing Two Commercial TIG Welding Machines for Deep Penetration MATEC Web of Conferences, 2019. 269: p. 1-5.
19. Shanping Lu, H.F., Kiyoshi Nogi, Sensitivity of Marangoni convection and weld shape variations to welding parameters in O2–Ar shielded GTA welding. Scripta Materialia 2004.
51: p. 271-277.
20. Keene, B.J., Review of data for the surface tension of pure metals. International Materials Reviews, 2013. 38: p. 157-192.
21. Shanping Lu, H.F., Kiyoshi Nogi, Marangoni convection and weld shape variations in Ar–O2 and Ar–CO2 shielded GTA welding. Materials Science and Engineering A 2004. 380: p.
290-297.
22. Y.L. Xu , Z.B.D., Y.H. Wei, C.L. Yang, Marangoni convection and weld shape variation in A- TIG welding process. Theoretical and Applied Fracture Mechanics, 2007. 48: p. 178-186.
23. C.X. Zhao, C.K., Y. Pan, I.M. Richardson, Z. Saldi, S. Kenjeres, C.R. Kleijn c, The effect of oxygen on transitional Marangoni flow in laser spot welding. Acta Materialia, 2010. 58: p.
6345-6357.
24. Snow, H.M.M., Investigation of the effect of a surface active flux on the microstructure and properties of gas tungsten arc welds made on a superaustenitic stainless steel, in
Materials Science and Engineering. 2002, Lehigh University.
25. E. S. SURIAN, J.L.T., T. BONISZEWSKI, Effect of Oxygen Content on Charpy V-Notch Toughness in 3%Ni Steel SMA Weld Metal. WELDING RESEARCH SUPPLEMENT, 1992: p.
263-268.
49
26. Ana Ma. Paniagua-Mercado, V.M.L.o.-H., Maribel L. Saucedo Mu˜noz, Influence of the chemical composition of flux on the microstructure and tensile properties of submerged- arc welds. Journal of Materials Processing Technology, 2005. 169(3): p. 346-351.
27. J. JANG, J.E.I., Inclusion effects on submerged arc weld microstructure. JOURNAL OF MATERIALS SCIENCE 1987. 22: p. 689-700.
28. R SAHOO, T.D., M.J. McNALLAN, Surface Tension of Binary Metal Surface Active Solute Systems under Conditions Relevant to Welding Metallurgy. METALLURGICAL
TRANSACTIONS B, 1988. 19B: p. 483-491.
29. BELTON, G.R., Langmuir Adsorption, the Gibbs Isotherm, and Interfacial Kinetics Metal Systems Adsorption in Liquid. METALLURGICAL TRANSACTIONS B, 1976. 78.
30. Kook-soo Bang, C.P., Hong-chul Jung, Effects of flux composition on the element transfer and mechanical properties of weld metal in submerged arc welding. Metals and Materials International, 2009. 15(3): p. 471-477.
31. Pei Wei Han, H.J.W., Shao-Jun Chu, The Calculation for Saturated Solubility of Oxygen in Mn–Si Melts Equilibrated with MnO–SiO2 Slags. High Temperature Materials and Processes, 2017. 36(1): p. 15-22.
32. K. C. Mills, B.J.K., R. F. Brooks, A. Shirali, Marangoni effects in welding. Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 1998. 356(1739): p. 911-925.
33. K. C. Mills, B.J.K., Factors affecting variable weld penetration. International Materials Reviews, 1990. Vol. 35: p. 185.
34. Shanping Lu, H.F., Hiroyuki Sugiyama, Manabu Tanaka and Kiyoshi Nogi, Weld Penetration and Marangoni Convection with Oxide Fluxes in GTA welding. Materials Transactions, 2002.
43: p. 2926-2931.
35. Z.D. Zhang, L.-M.L., Y. Shen, L. Wang, Welding of magnesium alloys with activating flux.
Science and Technology of Welding and Joining, 2005. 10: p. 737-743.
36. Sambherao, A.B., Use of Activated Flux For Increasing Penetration In Austenitic Stainless Steel While Performing GTAW. International Journal of Emerging Technology and Advanced Engineering, 2013. 3: p. 520-524.
37. Sang-Yoon Lee, Y.J.O., Kyung-Woo Y, Effects of Titanium and Oxygen Content on Microstructure in Low Carbon Steels. Materials Transactions, 2002. 43: p. 518-522.
38. Ana Ma. Paniagua-Mercado, V.M.L.-H., Hector J. Dorantes-Rosales, Paulino Estrada Diaz, Elvia Diaz Valdez, Effect of TiO2-containing fluxes on the mechanical properties and
50
microstructure in submerged-arc weld steels. Materials Characterization, 2008. 60: p. 36- 39.
39. D.W. OH, D.L.O., R. H. FROST The Influence of Boron and Titanium on Low-Carbon Steel Weld Metal. WELDING RESEARCH SUPPLEMENT, 1990: p. 151-158.