The main purpose of this thesis is to review short-wavelength laser-arc hybrid welding parameter on the quality and productivity of the various types of steel. In order to gain better understanding of arctic conditions, these are briefly discussed. To indicate possible applications of the materials, the most important offshore projects were introduced and briefly described.
Generally, hybrid welding provides many advantages. Recently, by developing fiber lasers hybrid welding can offer even more improvements. According to the analytical study of the hybrid welding parameters and comparing short-wavelength lasers (Nd:YAG, fiber and disk) with CO2 laser combined with arc source it can be concluded:
• Fiber laser-arc hybrid welding process offers improved joining capabilities due to short-wavelength and excellent laser beam properties therefore energy and cost savings, higher joining efficiency, deeper penetration, higher welding speed (at the same power level), improved weld quality and mechanical properties are achieved.
• Short-wavelength of fiber laser generates weakly ionised plasma compared to CO2 laser, as a result neither considerable absorption of the laser beam by plasma plume nor destabilisation of the metal transfer occurs.
• Fiber laser-MAG welding process promotes suitability to weld high strength steels up to 1100 MPa due to shallower HAZ zone width and little softening of the HAZ.
• Fiber laser due to its flexibility can be implemented to weld in Arctic conditions ‘‘in field‘‘, for example, in pipe-laying industry.
• Shielding gas used for fiber laser-arc hybrid welding is argon which is much cheaper than helium used for CO2 laser-arc hybrid welding. Moreover, addition of the CO2 or O2 shielding gas to argon further decrease the operating costs significantly and stabilise the arc during welding of steels.
• Leading arc process configuration provides higher penetration however it depends on the air gap widening, process distance and power levels of the sources.
• Leading arc process at higher welding speeds can be destabilise the keyhole since trajectory of the droplets are closer to the keyhole formation.
• Leading arc configuration is more prone to undercut formation whereas in trailing arc configuration sagging is highly probable.
• Trailing arc configuration provides better weld metal mixing and distribution of alloying elements due to inward molten metal flow. However oxygen can change molten metal
flow from inward to outward. In addition, the bridgeability is more improved compared to leading arc configuration.
• Implementation of the air gap in butt joints can be beneficial for improved mechanical properties of the weld and productivity.
• Optimal longitudinal process distance between source in case of short-wavelength lasers (fiber, disk, and Nd:YAG) is from 0 to 2-3 mm which is more closer than in case of CO2 lasers due to laser beam properties and laser-induced plasma plume dependency on the shielding gas composition.
• Increase in longitudinal process distance between source is harmful for penetration depth and weld metal mixing, however favours microstructural development.
• Mechanical properties can be improved further by increasing the arc power, however due to higher filler metal feed rate the keyhole might be destabilised.
• During hybrid welding, lower power level is required induce keyhole mode at low powers, therefore melting efficiency can be significantly improved.
• Additional heat from laser beam irradiation and plasma plume can change the metal transfer from short-circuiting into spray metal transfer mode.
• Coaxial hybrid welding offers even more advantages over paraxial arrangement of the welding sources however it can be limited in welding of thick plates due to degradation of the laser beam quality and limited power.
• By combining laser beam with MAG process provides the best option for filling grooves and bridgeability compared to other laser-arc combinations.
• An increase in arc current promotes higher absorption of the laser beam by arc plasma therefore penetration depth can be decreased.
• Focal point position in hybrid welding is tolerated in wide range compared to LBW whereas it significantly affects the penetration depth and geometry of the weld.
• Modulation of the laser beam provides extended capabilities in hybrid welding however synchronisation between laser beam and arc parameters is difficult to perform.
According to the major findings it can be also concluded that hybrid welding is a proven technology in joining of various thicknesses with improved mechanical properties.
Hybrid welding due to many additional arc parameters is flexible and adaptive joining process with high and even unexplored capabilities. Moreover, recent developments offers different and unique pulsing and other arc regimes with capabilities in building the unique
pulse shapes which provides opportunity to increase the productivity. Hybrid welding usually utilised CW laser mode which can cause certain problems for pulsed arc source, therefore the pulsed laser which is synchronised with an arc can improve process stability and even productivity. However, not much research is done in this particular phenomenon which can bring interesting results.
References
Abe, N., Kunugita, Y., Hayashi, M., Tsuchitani, Y., 1997. Dynamic Observation of High Speed Laser-Arc Combination Welding of Thick Steel Plates. Transactions of JWRI, 26(2), pp. 7-11.
Abt, F., Heß, A., Dausinger, F., 2008. Temporal Behaviour of the Focal Shift of Beam Forming Optics for High Power Single Mode Lasers. In Proc. of 27th International Congress on Applications of Lasers and Electro-Optics (ICALEO), October 20-23rd.
Temecula, California, USA. Laser Institute of America, pp. 561-568. 1302th paper.
Allen, C., Gerritsen, C., Zhang, Y., Mawella, J., 2007. Hybrid laser-MAG welding procedures and weld properties in 4 mm, 6 mm, 8 mm thickness C-Mn steel.
Intermediate Meeting. Vigo: IIW Commission.
Anon, 2001. Steel properties at low and high temperatures. [Online] Available at:
http://www.keytometals.com/page.aspx?ID=CheckArticle&site=kts&NM=48. [Accessed 29 March 2013].
Anon, 2010. Temperature Effects on Metal Strength. [Online] Available at:
http://www.roymech.co.uk/Useful_Tables/Matter/Temperature_effects.html. [Accessed 20 February 2013].
Anon, 2011. Application of Microalloyed HSLA Steel: Part One. [Online] Available at:
http://www.keytometals.com/page.aspx?ID=CheckArticle&site=kts&NM=347. [Accessed 20 March 2013].
Anon, n.d.a. Arctic oil and gas. [Online] Ernst & Young Available at:
http://www.ey.com/Publication/vwLUAssets/Arctic_oil_and_gas/$FILE/Arctic_oil_and_gas.pdf . [Accessed 5 March 2013].
Anon, n.d.b. Development in the Arctic: Economic opportunities, environmental and cultural challenges. [Online] GRID-Arendal Available at:
http://www.grida.no/publications/vg/arctic/page/2671.aspx. [Accessed 15 February 2013].
Anon, n.d.c. Gaussian Beam Optics. [Online] CVI Laser Optics and Melles Griot Available at:
https://www.cvimellesgriot.com/Products/Documents/TechnicalGuide/Gaussian-Beam-Optics.pdf. [Accessed 20 February 2013].
Anon, n.d.d. Oil spill contingency in the Arctic. [Online] Det Norske Veritas Available at:
http://www.dnv.no/Binaries/FINAL_Brochure_tcm155-524339.pdf. [Accessed 3 March 2013].
Antonsson, K., Grote, K.H., eds., 2009. Springer Handbook of Mechanical Engineering.
Springer, pp. 682-686.
Bang, H., Bang, H., Kim, J., Joo, S., 2010. Analysis of residual stress on AH32 butt joint by hybrid CO2 laser-GMA welding. Computational Materials Science, 49(2), pp. 217-221.
Bhadeshia, H., 2006. Steels: Microstructure and Properties. 3rd ed. Butterworth-Heinemann, pp. 222-306.
Blomquist, P., Chretien, C., Oller, E., Marx, B., 2009. Qualification of HLAW of HSLA-80 Under Naval Vessel Rules. In Proc. of 28th International Congress on Applications of Lasers and Electro-Optics (ICALEO), November 2-5th. Orlando, Florida, USA. Laser Institute of America, pp. 794-799. 1807th papaer.
Blondeau, R., 2008. Metallurgy and Mechanics of Welding. Wiley-ISTE.
Callister, D., Rethwisch, D., 2010. Materials Science and Engineering: An Introduction.
8th ed. John Wiley and Sons.
Canning, J., 2006. Fibre lasers and related technologies. Optics and Lasers in Engineering, 44(7), p. 647–676.
Cao, X., Wanjara, P., Huang, J., Munro, C., Nolting, A., 2011. Hybrid fiber laser – Arc welding of thick section high strength low alloy steel. Materials and Design, 32(6), pp.
3399-3413.
Chen, Y.B., Lei, Z.L., Li, Q., Wu, L., 2006. Experimental study on welding characteristics of CO2 laser TIG hybrid welding process. Science and Technology of Welding and Joining, 11(4), pp. 403-411.
Chen, Y.B., Miao, Y.G., Li, L.Q., Wu, L, 2008. Arc characteristics of laser-TIG double-side welding. Science and Technology of Welding and Joining, 13(5), pp. 438-444.
Dahotre, N.B., Harimkar, S., 2008. Laser Fabrication and Machining of Materials.
Springer.
Davis, J.R., 2006. Corrosion of Weldments. ASM International.
Doi, M., 2010. Coaxial hybrid process of hollow cathode TIG and YAG. Welding International, 24(3), pp. 188-196.
Easterling, E., 1983. Introduction to the Physical Metallurgy of Welding. Butterworth-Heinemann Ltd., pp. 126-136.
El Rayes, M., Walz, C., Sepold, G., 2004. The Influence of Various Hybrid Welding Parameters on Bead Geometry. Welding Journal, pp. 143-153.
Eriksson, I., Powell, J., Kaplan, A., 2013. Guidelines in the choice of parameters for hybrid laser arc. Physics Procedia, 41, pp. 119-127.
Fellman, A., 2008. The effects of some variables on CO₂ laser-MAG hybrid welding.
D.Sc. Technology Thesis. Lappeenranta: Lappeenranta University of Technology.
Fellman, A., Salminen, A., 2007. Study of the Phenomena of Fiber Laser-MAG Hybrid Welding. In Proc. of 26th International Congress on Applications of Lasers and Electro-Optics (ICALEO), October 29th to November 1st. Orlando, Florida, USA. Laser Institute of America, pp. 871-880. 1604th paper.
Fellman, A., Westin, E., 2008. Fiber Laser Hybrid Welding of Stainless Steels. In Proc. of 27th International Congress on Applications of Lasers and Electro-Optics (ICALEO), October 20-23rd. Temecula, California, USA. Laser Institute of America, pp. 545-553.1204th paper.
Ferjutz, K., Davis, J.R., 2004. ASM Handbook: Volume 6: Welding, Brazing, and Soldering. ASM International.
Fukami, K., Setoda, K., 2013. Development of high-efficiency MIG-laser hybrid welding technology. Welding International, 27(2), pp. 87-92.
Funderburk, S., 1999. A Look at Heat Input. Welding Innovation, XVI(1).
Gao, M., Zeng, Y., Hu, W., Yan, J., 2008. Weld microstructure and shape of laser–arc hybrid welding. Science and Technology of Welding and Joining, 13(2), pp. 106-113.
Gerritsen, C., Allen, C., Mawella, J., 2005. Development and Evaluation of CO2 Laser-MAG Hybrid Welding for DH36 Shipbuilding Steel. In 11th CF/DRDC International Meeting on Naval Applications of Materials Technology. Halifax, Nova Scotia, Canada.
Gerritsen, C., Weldingh, J., Kristensen, J., 2005. Development of Nd:YAG Laser-MAG Hybrid Welding of T-joints for Shipbuilding. In Proceedings of the 10th Nordic Laser Materials Processing Conference (NOLAMP), August 17-19th. Lulea, Sweden. Lulea University of Technology.
Göbel, G., Brenner, B., Beyer, E., 2007. New application possibilities for fiber laser welding. In Proc. of 26th International Congress on Applications of Lasers and Electro-Optics (ICALEO), October 29th to November 1st. Orlando, Florida, USA. Laser Institute of America, pp. 102-108. 209th paper.
Gook, S., Gumenyuk, A., Lammers, M., Rethmeier, M., 2011. Pipe Girth Welding Using a High-Power Fibre Laser. In Proceedings of the 13th Nordic Laser Materials Processing Conference (NOLAMP), June 27-29th. Trondheim, Norway. Norwegian University of Science and Technology.
Grong, O. 1994. Metallurgical Modelling of Welding. Maney Pub.
Grünenwald, S., Seefeld, T., Vollertsen, F., Kocak, M., 2010. Solutions for joining pipe steels using laser-GMA-hybrid welding processes. Physics Procedia, 5, p. 77-87.
Hayashi, T., Katayama, S., Abe, N., Omori, A., 2003. High-power CO2 laser-MIG hybrid welding for increased gap tolerance. Hybrid weldability of thick steel plates with a square groove. Welding International, 18(9), pp. 692-701.
Hochhauser, F., Ernst, W., Rauch, R., Vallant, R., Enzinger, N., 2012. Influence of the Soft Zone on The Strength of Welded Modern HSLA Steels. Welding in the World, 56(5-6), pp.
77-85.
Hong, S.G., Lee, J.B., 2007. Effects of Hybrid Welding Parameters on the Toughness of Weld Metal in Ship Structural Steel. In Proc. of 26th International Congress on
Applications of Lasers and Electro-Optics (ICALEO), October 29th to November 1st.
Orlando, Florida, USA. Laser Institute of America, pp. 935-939. P520th paper.
Howse, D., Scudamore, R., Booth, G., 2005. Yb fibre laser/MAG hybrid processing for welding of pipelines. Prague: Commission IV (Power Beam Processes) 58th IIW Annual Assembly TWI.
Huang, Y., Zhang, Y.M., 2010. Laser-Enhanced GMAW. Welding Journal, 89(9), pp. 181-188.
Hu, B., den Ouden, G., 2005. Laser induced stabilisation of the welding arc. Science and Technology of Welding and Joining, 10(1), pp. 76-81.
Hu, B., den Ouden, G., 2005. Synergetic effects of hybrid laser/arc welding. Science and Technology of Welding and Joining, 10(4), pp. 427-431.
Hügel, H., 2000. New solid-state lasers and their application potentials. Optics and Lasers in Engineering, 34(4-6), pp. 213–229.
Iadicicco, A., Paladino, D., Moccia, M., Quero, G., Campopiano, S., Bock, W. J., Cusano, A., 2013. Mode coupling and field distribution in sub-mm permanently bent single mode optical fibers. Optics and Laser Technology, 47, pp. 292–304.
Imai, S., 2002. General Properties of TMCP Steels. In International Offshore and Polar Engineering Conference, Kitakyushu, 2002.
Injeyan, H., Goodno, G., 2011. High Power Laser Handbook. McGraw-Hill Professional.
Ion, J., 2005. Laser Processing of Engineering Materials: Principles, Procedure and Industrial Application. Butterworth-Heinemann.
Ilic A., Ivanovic L., Josifovic D., Lazic V., 2012. Design Apects at Mechanical Constructions Made of High Strength Steel Grades. Machine Design, 4 (3). ISSN 1821-1259, pp. 131-138.
Ishide, T., Tsubota, S., Watanabe, M., Ueshiro, K., 2010. Development of TIG-YAG and MIG-YAG hybrid welding. Welding International, 17(10), pp. 775-780.
Jackson, H.M., 2011. Melting Boundaries: Rethinking Arctic Governance. [Online] Task Force on Arctic Governance Available at:
http://staff.washington.edu/nfabbi/taskforce/MeltingBoundaries.pdf. [Accessed 15 March 2013].
Joo, S.M., Kim, Y.P., Ro, C.S., Bang, H.S., Park, J.U., 2004. Basic Experiments by Hybrid Welding to Steels for Shipbuilding. Key Engineering Materials, August. pp. 2383-2388.
Kannatey-Asibu Jr., E., 2009. Principles of Laser Materials Processing. Wiley.
Kaplan, A., 2011. Modelling the Primary Impact of an Yb:Fibre Laser Beam Profile on the Keyhole Front. Physics Procedia, 12, pp. 627-637.
Karlsson, J., Kaplan, A., 2012. Comprehensive Monitoring and Control of Laser Hybrid Arc Welding in Industrial Production. In Proceeding of 31th International Congress on Applications of Lasers and Electro-Optics (ICALEO), September 23-27th. Anaheim, California, USA. Laser Institute of America, pp. 220-227. 605th paper.
Katayama, S., Kawahito, Y., 2009. Elucidation of phenomena in high-power fiber laser welding and development of prevention procedures of welding defects. SPIE Proceedings Vol. 7195 . Fiber Lasers VI: Technology, Systems, and Applications, February 19th.
Katayama, S., Kawahito, Y., Mizutani, M., 2010. Elucidation of laser welding phenomena and factors affecting weld penetration and welding defects. Physics Procedia, 5, pp. 9–
17.
Katayama, S., Naito, Y., Uchiumi, S., Mizutani, M., 2006. Physical Phenomena and Porosity Prevention Mechanism in Laser-Arc Hybrid Welding. Transactions of JWRI, 35(1), pp. 13-18.
Katayama, S., Yohei, A., Mizutani, M., Kawahito, Y., 2011. Development of Deep Penetration Welding Technology with High Brightness Laser under Vacuum. Physics Procedia, 12, pp. 75-80.
Kawahito, Y., Mizutani, M., Katayama, S., 2008. Optical Interaction between Laser Beam and Induced Plume in the Ultra-High Power Density Fiber Laser Welding of Stainless Steel. Transaction of JWRI, 37(2), pp. 19-25.
Kelly, S.M., Brown, S.W., Tressler, J.F., Martukanitz, R.P., Ludwig, M.J., 2009. Using Hybrid Laser-Arc Welding to Reduce Distortion in Ship Panels. Welding Journal, 88(3), pp. 32-36.
Khan, I., 2009. Welding Science and Technology. New Age International Pvt Ltd Publishers.
Kim, Y.S., Eagar, T., 1993. Analysis of Metal Transfer in Gas Metal Arc Welding. Welding Journal, pp. 269-278.
Kim, Y.S., Eagar, T.W., 1993. Metal Transfer in Pulsed Current Gas Metal Arc Welding.
Welding Journal, 72(7), pp. 279-287.
Kim, Y.S., Lim, H., Kim, J., 2008. Position welding using disk laser-GMA hybrid welding.
Journal of Achievements in Materials and Manufacturing Engineering, 28(1), pp.83-86.
Komizo, Y., 2007. Status and Prospects of Shipbuilding Steel and Its Weldability.
Transactions of JWRI, 36(1), pp. 1-6.
Kou, S., 2002. Welding Metallurgy. 2nd ed. Wiley-Interscience, pp. 393–410.
Laitinen, R., Siltanen, J., Porter, D., Kömi, J., 2009. Laser-MAG Hybrid Welding of Direct Quenched High Strength Steel Grade S690QL. In Proceedings of the 12th Nordic Laser Materials Processing Conference (NOLAMP), August 24-26th. Copenhagen, Denmark.
Laitinen, R., Tihinen, S., Siltanen, Kömi, J., 2013. Laser-GMA Hybrid Welding of High Strength Steel Grades With The Yield Stength of 700 MPa. In Proceedings of the 14th Nordic Laser Materials Processing Conference (NOLAMP), August 26-28th. Gothenburg, Sweden. Lulea University of Technology.
Lancaster, J., 1999. Metallurgy of Welding. 6th ed. Woodhead Publishing.
Lappalainen, E., Purtonen, T., Salminen, A., 2011. Effect of Arc Parameters in High Brightness Hybrid Laser Arc Welding of Low Alloyed Steel. In Proc. of 30th International Congress on Applications of Lasers and Electro-Optics (ICALEO), October 23-27th. Orlando, Florida, USA. Laser Institute of America, pp. 599-605. 1504th paper.
Le Guen, E., Fabbro, R., Carin, M., Coste, F., Le Masson, P., 2011. Analysis of hybrid Nd:Yag laser-MAG arc welding processes. Optics and Laser Technology, 43(7), pp. 1155-1166.
Lee, M.Y., 2008. The Effect of Shielding Gas on Deep Penetration High Power Fiber Laser Welding of Thick Plate Steel for Pipe Line Construction. In Proceeding of 27th International Congress on Applications of Lasers and Electro-Optics (ICALEO), October 20-23rd. Temecula, California, USA. Laser Institute of America, pp. 380-386. 706th paper.
Leiviskä, P., Fellman, A., Laitinen, R., Vänskä, M., 2007. Strength properties of laser and laser hybrid welds of low alloyed high strength steels. In Proceedings of the 11th Nordic Laser Materials Processing Conference (NOLAMP), August 20-22th. Lappeenranta, Finland.
pp. 173-184. ISBN 978-952-214-412-6.
Liu, Z., Kutsuna, M., Xu, G., 2006. Fiber Laser Welding of 780MPa High Strength Steel. In Proceeding of 25th International Congress on Applications of Lasers and Electro-Optics (ICALEO), 30th October to 2nd November. Scottsdale, Arizona, USA. Laser Institute of America, pp. 562-568. 1101th paper.
Liu, S., Liu, F., Hong, Z., Yan, S., 2012. Analysis of droplet transfer mode and forming process of weld bead in CO2 laser-MAG hybrid welding process. Optics and Laser Technology, 44(4), pp. 1019-25.
Liu, Z., Xu, G., Kutsuna, M., 2008. Laser and laser-MAG hybrid welding of high strength steel using fiber laser and CO2 laser. Welding International, 22(1), pp. 23-28.
Liu, M., Yuan, T., Li, C.B., 2012. Effect of relative location of laser beam and TIG arc in different hybrid welding modes. Science and Technology of Welding and Joining, 17(6), pp. 441-446.
Li, Z., Wang, W., Wang, X., Li, H., 2010. A study of the radiation of a Nd:YAG laser–MIG hybrid plasma. Optics and Laser Technology, 42(1), pp. 132-140.
Mackwood, A.P., Crafer, R.C., 2005. Thermal modelling of laser welding and related processes: a literature review. Optics and Laser Technology, 37(2), pp. 99–115.
Mahrle, A., Schnick, M., Demuth, C., Beyer, E., Fussel, U., 2011. Process characteristics of fibre-laser-assisted plasma arc welding. Journal of Physics D: Applied Physics, 44(34).
Mahrle, A., Schnick, M., Pinder, T., Beyer, E., Füssel, U., 2012. Development and Experimental Analysis of Laser-Assisted Plasma Arc Welding. In Proceeding of 31th International Congress on Applications of Lasers and Electro-Optics (ICALEO), September 23-27th. Anaheim, California, USA. Laser Institute of America, pp. 435-444.1302th paper.
Maurer, W., Ernst, W., Rauch, R., Kapl, S., Pohl, A., Krussel, T., Vallant, R., Enzinger, N., 2012. Electron Beam Welding of a TMCP Steel With 700 MPa Yield Strength. Welding in the World, 56(9-10), pp. 85-94.
Mazerov, K., 2012. The Arctic: Confronting the cold, hard truths about the last frontier.
[Online] Available at: http://www.drillingcontractor.org/the-arctic-confronting-the-cold-hard-truths-about-the-last-frontier-13206. [Accessed 3 April 2013].
McPherson, N., Suarez-Fernandez, N., Moon, D., Tan, C., Lee, C., Baker, T., 2005. Laser and laser assisted arc welding processes for DH36 microalloyed steel ship plate.
Science and Technology of Welding and Joining, 10(4), pp. 460-467.
Messler, R.W., 1999. Principles of Welding. Wiley-VCH.
Migliore, L.R., ed., 1996. Laser Materials Processing. CRC Press.
Miranda, R., Costa, A., Quintino, L., Yapp, D., Iordachescu, D., 2009. Characterization of fiber laser welds in X100 pipeline steel. Materials and Design, 30(7), pp. 2701-2707.
Mulima, J.B., 2008. Hybrid laser arc welding with high power diode laser. D.Sc.
Technology Thesis. Wollongong: University of Wollongong.
Munro, C., Nolting, A., Cao, X., Wanjara, P., 2012. Hybrid Laser-Arc Welding of HSLA-65 Steel Plate: Microstructural and Mechanical Property Evaluation of Butt Welds.
Materials Science Forum, January. pp. 2992-2997.
Naito, Y., Mizutani, M., 2003. Observation of Keyhole Behavior and Melt Flows during Laser-Arc Hybrid Welding. In Proc. of 22th International Congress on Applications of Lasers and Electro-Optics (ICALEO), October 13-16th. Jacksonville, Florida, USA. Laser Institute of America, pp. 159-167. 1005th paper.
Olsen, F., 2009. Hybrid laser-arc welding. Woodhead Publishing.
Onishi, T., Mizutani, M., Kawahito, Y., Katayama, S., 2009. High-power Fiber Laser Butt Welding of Thick High-strength Steel Plate using Sensing System with Hot Wire. In Proc. of 28th International Congress on Applications of Lasers and Electro-Optics (ICALEO), November 2-5th. Orlando, Florida, USA. Laser Institute of America, pp. 773-779. 1804th paper.
Ono, M., Shinbo, Y., Yoshitake, A., Ohmura, M., 2002. Development of Laser-arc Hybrid Welding. NKK Technical Review No. 86, pp. 8-12.
Orbeck-Nilssen, K., 2012. The Arctic – a region of opportunity and interest. [Online]
Available at:
http://www.dnv.com/industry/oil_gas/publications/updates/arctic_update/2012/01_2012/The_
Arctic__a_region_of_opportunity_and_interest.asp. [Accessed 25 February 2013].
Ozden, H., 2007. Investigating Fiber Lasers for Shipbuilding and Marine Construction.
Welding Journal, pp. 26-29.
Paschotta, R., 2010. Field Guide to Optical Fiber Technology. Spi ed. SPIE Publications.
Petring, D., Fuhrmann, C., 2004. Recent Progress and Innovative Solutions for Laser-Arc Hybrid Welding. In Proceedings of the 1st Pacific International Conference on Application of Lasers and Optics.
Petring, D., Fuhrmann, C., Wolf, N., Poprawe, R., 2007. Progress in laser-MAG hybrid welding of high-strength steels up to 30mm thickness. In Proc. of 26th International Congress on Applications of Lasers and Electro-Optics (ICALEO), October 29th to November 1st. Orlando, Florida, USA. Laser Institute of America, pp. 300-307. 604th paper.
Petring, D., Fuhrmann, C., Wolf, N., Poprawe, R., 2007. Progress in laser-MAG hybrid welding of high-strength steels up to 30mm thickness. In Proc. of 26th International Congress on Applications of Lasers and Electro-Optics (ICALEO), October 29th to November 1st. Orlando, Florida, USA. Laser Institute of America, pp. 300-307. 604th paper.