In this doctoral thesis the usability of HSS in welded structures has been researched. Welded QT, TMCP and DQ HSSs have been under examination.
The use of these HSSs grows in many industrial areas and the need for knowledge of these steels structures manufacturing is in high demand.
Today, HSS is manufactured using three different methods, QT, TMCP and DQ.
The microstructure of these steels and HAZ area after welding, mechanical properties, usability, and other main discrepancies in the welded structures were researched. Only after carefully clarifying the research topic and discusses welded high strengths structures was experimental research done using different laboratory tests. These tests were all conducted with undermatched filler material with three different heat inputs, 1.0, 1.3 and 1.7 kJ/mm.
The research carried out during this doctoral thesis had four key findings.
1) A clear implication of this study points out that when welding HSS, thickness 8 mm and butt joint, the heat input must be 1.0 kJ/mm or lower. HSS steels with a heat input of 1.0 kJ/mm have better HAZ microstructures and additionally superior tensile strength and impact test values than steels with a heat input of 1.3 or 1.7 kJ/mm.
2) When welding all three types of HSS (QT, DQ and TMCP), the CGHAZ was very brittle. This brittleness occurred because of the high heat input used during the welding process causes dissolve of carbides and nitrides and also growing of initial austenite grains. The CGHAZ is narrow using low heat input and in normal steels structures it does not significantly weaken the structure. However, if the steel structure is loaded in low temperatures, from -20 °C to -40 °C, then the CGHAZ could be the area from which failure can occur.
159
3) The tensile strength of the welded structures was acceptable. Although the tensile strength of the filler material was only 72 % of base material’s tensile strength, some welded structures had nearly the same tensile strength as the base material.
Elongation at break values in all the welded structures were low. Values of 6.1
% where observed when the heat input was 1.0 kJ/mm, 7.1 % when the heat input was 1.3 kJ/mm and 7.0 % when the heat input was 1.7 kJ/mm. These values are only half of the required 15 % necessary for HSSs. The same situation occurs in real welded structures when using undermatching filler material, and the main yield will occur in the weld. Designers of steel structures must consider that the majority of the yielding will happen in the weld.
4) When welding HSSs with a yield strength of 700 MPa, using undermatched filler material is an acceptable method. This undermatched filler material will survive as a filler metal. However, planning ahead and careful welding are the best guarantees to ensure a positive result when welding HSSs.
160
References
Basu, B. Raman, R. Microstructural Variations in a High-Strength Structural Steel Weld under Isoheat Input Conditions. Welding Journal, pp. 239- 248.
2002.
Cabello, F. G. Chao, J. Cornide, J. Gardía-Mateo, C. Santofimia, M. J. Cap-devila, C. Toughness deterioration in advanced high strength bainitic steels.
Materials Science and Engineering A, vol. 525, pp. 87-95. 2009.
Chen, Y. T. Guo, A. M. Wu, L. X. Zeng, J. Li, P. H. Microstructure and mechani-cal property development in the simulated heat affected zone of V treated HSLA steels. Acta Metallurgica Sinica, vol. 19, no 1. pp. 57-76. 2006.
Davis, C.L. King, J.E. Effect of cooling rate on intercritically reheated microstructure and toughness in high strength low alloy steel. Materials Science
& Techology, vol. 9, pp 8. 1993.
Dillinger Hüttenwerke AG, Dillimax ppt document via e-mail. 2008.
Duane, K. Miller, P. E. Use Undermatching Weld Metal Where Advantageous.
Welding Innovation, vol. XIV, no 1. 1997.
Easterling K. Introduction to the physical metallurgy of welding. 2nd edition// But-terworth-Heinemann Ltd., 1992.
Esab Dalsbruk Oy. OK Autrod 12.51. Test Certificate 0010028133. 2008.
Güral, A. Bostan, B. Özdemir, A.T. Heat treatment in two phase region and its effect on microstructure and mechanical strength after welding of a low carbon steel. Material and Design. 2007.
161
Hamada, M. Control of strength and toughness at the heat affected zone. Weld-ing International, vol. 17, no 4, pp. 265-270. 2003.
Harrison, P. Wall, P. Effect of alloying elements on HAZ microstructure and toughness, EU raportti EN 15834. Europa Comission. Technical Steel Re-search. p.79. 1996.
Hatting, R, J. Pienaar, G. Weld HAZ embrittlement of Nb containing C-Mn steels. International Journal of Pressure Vessels and Piping, vol. 75, pp. 661-667. 1998.
Holsberg, P. W. Gudas, J. P. Caplan, I. L. Metallurgical design and processes in the U.S. Navy HSS welding. Recent Trends in Welding Science and Technol-ogy TWR’89, edited by S. A. Daid and J. M. Vitek. 1989.
Hwang, G.C. Lee, S. Yoo, J. Y. Choo, W. Y. Effect of direct quenching on mi-crostructure and mechanical properties of copper-bearing high-strength alloy steels. Material Science and Engineering A252, p. 256-268. 1998.
Juan, W. Yajiang, L. Peng, L. Effect of weld heat input on toughness and struc-ture of HAZ of a new super-HSS. Bulletin Material Science, vol 26, no 3, pp.
301-305. 2003.
Kapustka, N. Conrardy, C. Baby, S. Albrigth, C. Effect of GMAW Process and Material Conditions on DP 780 and TRIP 780 Welds. Welding Journal, vol. 87, pp. 135-148. 2008.
Keehan, E. Effect of Microstructure on Mechanical Properties of HSS Weld Metals. Thesis for the degree of doctor of philosopfy. Chalmers University of technology and Göteborg University, Göteborg, Sweden. 2004.
Keehan, E. Andrén, H. O. Karlsson, L. Murugananth, M. Bhadeshia, H. K. D. H.
Microstructural and mechanical effects of nickel and manganese on HSS weld
162
metals. Trends in Welding Research, Proc. 6th Int. Conf., Eds. SA David, T De-bRoy, JC Lippold, HB Smartt and JM Vitek. ASM International, Materials Park, pp. 695-700, 2003.
Kim, B. C. Lee, S. Kim, N. Lee, D. Y. Metallurgical and Materials Transaction A, vol. 22A, pp 139. 1991.
Kou, S. Welding Metallurgy, Second Edition. Hoboken, N.J.: John Wiley &
Sons, Inc. 2003.
Krauss G., Thompson S.W. Ferritic microstructures in continuously cooled low- and ultralow-carbon steels, ISIJ International, 35, No.8, 937-945, 1995.
Kömi, J. Ultralujat kuumavalssatut ratkaisut painokriittisiin sovelluksiin - teräsra-kenteiden optimointi superteräksistä. Ultralujat ja kulutusta kestävät teräkset pe-rinteisten terästen korvaavina materiaaliratkaisuina Teknologia Kuopio, semi-naarisarja: Savonia-ammattikorkeakoulu Tekniikka. Rautaruukki Ltd, 2009. (in Finnish)
Lambert, A. Drillet, J. Gourgues, A.F. Sturel, T. Pineau, A. Microstructure of martensite-austenite constituents in heat affected zones of high strength low al-loy steel welds in relation to toughness properties. Science and Technology of Welding and Joining, vol. 5, no 3, 168-173. 2000.
Lamberte-Perlade A., Gourgues A.F., Besson J., Sturel T., Pineau A. Mehanism and modeling of clivage fracture in simulated heat-affected zone microstruc-tures of a high-strength low alloy steel, Metall. Trans. A, vol. 35A, 1039-1053, 2004.
Lancester, J. F. Metallurgy of welding. Third Edition. ISBN 0-04-669008-5.
George Allen & Unwill Ltd. 1980.
163
Lee, S. Kim, B. C. Kwon, D. Fracture Toughness Analysis of Heat-Affcted Zones in High-Strength Low-Alloy Steel welds. Metallurgical Transactions A, vol. 24A, 1134-1141. 1993.
Lee, J-L. Pan, Y-T. The formation of intragranular acicular ferrite in simulated heat affected zone. ISIJ International, vol. 35, no. 8, pp. 1027-1033. 1995.
Li, Y. Crowther, D, N. Green, M, J, W. Mitchell, P, S. Baker, T, N. The effect of Vanadium and Niobium on the Properties and Microstructure of the Intercritically Reheated Coarce Grained Heat Affected Zone in Low Carbon Microalloyed Steels. ISIJ International, Vol. 41, No 1, p. 46-55. 2001.
Lindroos, V. Sulonen, M. Veistinen, M. Uudistettu Miekkojan metallioppi. Tek-nisten tieteiden akatemia. Kustannusosakeyhtiö Otava. Helsinki. 1986. (In Fin-nish)
Liu, S. Liao, F-C. Precipitate stability in the heat affected zone of nitrogen-enchanced high strength low alloy steels. Materials Science & Engineering A244, pp. 273-283. 1998.
Liu, W-Y. Wang, L, Liu, J-B. Zhang, Y-Y. Li, P-H. Yuan,G-L. Microstructures and Properties in Simulated Heat-Afeected Zones of 685 MPa Grade Copper-Bearing Steel. Proceedings of Sino-Swedish Structural Materials Symposium.
2007.
Loureiro, A.J.R. Effect of heat input on plastic deformation of undermatched welds. Journal of Materials Technology, vol 128, pp. 240-249. 2002.
Magudeeswaran,G. Balasubramanian, V. Madhusudhan Reddy, G.
Balasubramanian, T.S. Effect of Welding Processes and Consumables on Tensile and Impact Properties of High Strength Quenched and Tempered Steel Joints. Journal of Iron and Steel Researce, International, 15, pp. 87-94. 2008.
164
Matsuda, F. Ikeuchi, K. Fukada, Y. Horii, Y. Okada, H. Shiwaku, T. Shiga, C.
Suzuki, S. Review of Machanical and Metallurgical Investigations of M-A Consti-tuent in Welded Joint in Japan. Transaction of JWRI in published by welding re-search, Institute, Osaka University, Ibaraki, Osaka 567, Japan. 1995.
Matsuda F., Fukada Y., Okada H., C.Shiga Review of mechanical and metallur-gical investigations of martensite-austenite constituent in welded joints in Japan, Welding in the World, No.3, Vol.37, 134-154, 1996.
Mee van der, V. J. H. M, Pletcher, P. M. Consumables and practices for welding HSSs. Singapore 2009.
Metals Handbook Tenth Edition, Volyme 1, Properties and Selection: Iron, Steels, and High Performance alloys. Prepared under the direction of the ASM INTERNATIONAL Handbook Committee. 1990.
Miki, C. Homma, K. Tominaga, T. High strenth and high performance steels and their use in bridge structures. Journal of Constructional Steel Research, vol 58, pp. 3-20. 2002.
Misra, R. D. K. Nathani, H. J.E. Hartmann, J. E. Siciliano, F. Microstructural evolution in a new 770 MPa hot rolled Nb–Ti microalloyed steel. Materials Science and Engineering A 394, p 339–352. 2005.
Mitchell P.S., Hart P.H.M., Morrison W.B. The effect of microalloying on HAZ toughness, MICROALLOING 95, Eds. M.Korchynsky et. al., I&SS, Pittsburgh, USA, 1995.
Mohandas, T. Madhusudan Reddy, G. Satish Kumar, B. Heat-affected zone softening in high-strength low-alloy steels. Journal of Materials Processing Technology 88, pp. 284-294. 1999.
165
Moon, D. W. Fonda, R. W. Spanos, G. Microhardness Variations in HSLA-100 Welds Fabricated with New Ultra-Low-Carbon Weld Consumables. Welding Research Supplement, October, pp. 278-285. 2000.
Moon, J. Kim, S. Lee, J. Hwang, B. Lee, C.G. Lee, C. Effect of Cu and B addition on tempering behaviour in the weld CGHAZ of high strength low alloy plate steel. Materials Science and Engineering A 497, pp 153-159. 2008.
Nevasmaa, P. Cederber, M. Vilpas, M. Weldability of direct-quenched and tempered (DQT) HSS HT80. Technical Research Centre of Finland. 1992A.
Nevasmaa, P. Cederberg, M. Vilpas, M. Weldability of accelerated-cooled (AcC) high strength TMCP steel X80. Technical Research Centre of Finland. 1992B.
Pacyna, J. Dabrowski, R. New alloy steel of high strength and resistance to cracking. Welding International, vol. 21, no 5, pp.20-23. 2007.
Pisarski, H.G. Dolby, R.E. The significance of softened HAZs in high strength structural steels. Welding in the World, vol. 47, no 5/6, pp. 32-40. 2003.
Porter, D. Development in hot-rolled high-strength steel. Nordic welding conference 06, New trends in welding technology, Tampere, Finland. 2006.
Rak, I. Kocak, M. Gliha, V. Gubeljak, N. Prauseis, Z. Effect of Strength Mismatch on Fracture Toughness of HSLA Steel Weld Joint. OMAE, Volyme III, Materials Engineering, ASME, 1995.
Rak, I. Gliha, V. Kocak, M. Weldability and Toughness Assessment of Ti-Microalloyed Offshore Steel. Metallurgical and Materials Transactions A, vol 28A, 1997.
166
Ramirez, J.E. Characterization of High-Strength Steel Weld Metals: Chemical Composition, Microstructure, and Non metallic Inclusions. Welding Journal, vol.
87, pp. 65-75. 2008.
Rodrigues, D.M. Menezes, L.F. Loureiro, A. Fernandes, J.V. Numerical study of plastic behaviour in tension of welds in high strength steels. International Jour-nal of Plasticity, vol 20, pp. 1-18. 2004a.
Rodrigues, D.M. Menezes, L.F. Loureiro, A. The influence of the HAZ Softening on the Mechanical Behaviour of Welded Joints Containing Cracks in the Weld Metal. Engineering Fracture Mechanics, 71, issues13-14, pp. 2053-2064.
2004b.
Sampath, K. An understanding of HSLA-65 plate steels, Journal of Materials Engineering and Performance, Vol 15 (1). 2006.
Satoh, K. Toyota, M. Joint Strength of Heavy Plates with Lower Strength Weld Metal. The 56th AWS Annual Meeting. Welding Journal 54 9 p (Reprinted Version). 1975.
Shi, Y. Han, Z. Effect of weld thermal cycle on microstructure and fracture toughness of simulated heat-affected zone for a 800 MPa grade HSS. Journal of materials processing technology 207, pp. 30-39. 2008.
Shi, Y. Han, Z. Fu, J. Effect of weld strength undermatch on fracture toughness of HAZ notched in a HSLA steel. International Journal of Fracture, vol. 91, pp.
349-358. 1998.
Shishida et al: Study of Steel Manufacture 1987 326 36.
Tian, D. Microstructure, cleavage fracture and toughness of granular bainite in simulated coarse-grained heat affected zones of low-carbon
high-strength-167
steels. Oulu: Oulun yliopisto, Acta Universitatis Ouluensis. Series C, Technica, 113, ISBN 951-42-4802-5. 1998.
Toyoda, M. Practical Fracture Mechanics & Welding Mechanics (With particular Reference to Structural Integrity in Weldments). Japan 1986. Osaka University.
P, 1-62. 1986.
Thewlis, G. Classification and quantification of microstructures in steels. Mate-rials Science and Technology, vol 20, no 2, pp.143-160. 2004.
Umekuni, A. Masubuchi, K. Usefulness of Undermatched Welds for High-Strength Steels. Welding Journal, vol. 76, No 7, pp. 256-263. 1997.
Vilpas, M. Tihekari, H. Karppi, R. Mechanical properties of SMA- and SA-welded joints for quenched and tempered high-strength steel, N-A-XTRA 70.
Technical Research Centre of Finland. Research report 363. 1985.
Vähäkainu, O. Hitsaajan opas. Rautaruukin teräkset. Otavan kirjapaino. Keuruu.
2003. (in finnish)
Wang, J. Li, Y. Liu, P. Effect of weld heat input on toughness and structure of HAZ of a new super-HSS, Material Science, Vol 26, No 3, pp 301-305. 2003.
Yayla, P. Kaluc, E. Ural, K. Effect of welding processes on the mechanical properties of HY 80 steel weldment. Material and Design, vol 28, pp. 1898-1906. 2007.
Yurioka, N. Okumura, M. Kasuya, T. Cotton, H. J. U. Prediction of hardness of transformable steels, Metal Construction, vol 19, pp. 217-223. 1987.
Yasuyama, M. Uchihara, M. Fukui, K. Tailored blank technology of HSS sheet.
Welding International, vol. 21, no 4, pp. 251-254. 2007.
168
Zaczek, Z. Cwiek, J. Prediction of HAZ Hardness in Welds of Quenched and Tempered HSLA Steels. Welding Journal, vol 72, no 1, pp. 37-40. 1993.
Zeman, M. Assesment of weldability of WELDOX 1100 high strength quenched and tempered steel. Welding International, vol. 23, no 2, pp. 79-82, 2009a.
Zeman, M. Properties of welded joints made of weldox 1100 Steel. Welding In-ternational, vol. 23, no 2, pp. 83-90, 2009b.
Zhang, Y. Q. Zhang, H, Q. Liu, W, M. Hou, H. Effects of Nb on microstructure and continuous cooling transformation of coarse grain heat-affected zone in 610MPa class high-strength low-alloy structural steels. Materials Science and Engineering A 499, p. 182–186. 2009.
Network documents
http://www.worldautosteel.org/uploaded/AHSSApplicationGuidelinesVersion4.p df
(read 3.6.09)
Appendix 1.
169
Prequalified Welding Procedure Specification, pWPS, heat input 1.0 kJ/mm
Base Materials
HSS, yield strength 700 MPa
Thickness 8 mm Type of joint preparation Weld pass sequence
Outside diameter of pipe V-Groove 60 °
Welding process MAG
Backing ring Fiberglass tape
Cutting-edge angle
Filler material and shielding gas Torch angle 0°
Classification of filler
OK AUTROD 12.51 Elevated working temperature
Interpass temperature 20 °C
Powder Preheating temperature
Flow rate range Heating rate
Backing gas Soaking temperature
Flow rate range Soaking time
Type of current DC
Cooling rate
Polarity
+ pole
Finishing
Notes: Backing ring was woven glass Date and author: 07.04.2009 MPirinen
Bead Welding
Appendix 2.
170
Prequalified Welding Procedure Specification, pWPS, heat input 1.3 kJ/mm
Base Materials
HSS, yield strength 700 MPa
Thickness 8 mm Type of joint preparation Weld pass sequence
Outside diameter of pipe V-Groove 60 °
Welding process MAG
Backing ring Fiberglass tape
Cutting-edge angle
Filler material and shielding gas Torch angle 0°
Classification of filler
OK AUTROD 12.51 Elevated working temperature
Interpass temperature
Flow rate range Heating rate
Backing gas Soaking temperature
Flow rate range Soaking time
Type of current
Notes: Backing ring was woven glass Date and author: 07.04.2009 MPirinen
Bead Welding
Appendix 3.
171
Prequalified Welding Procedure Specification, pWPS, heat input 1.7 kJ/mm
Base Materials
HSS, yield strength 700 MPa
Thickness 8 mm Type of joint preparation Weld pass sequence
Outside diameter of pipe V-Groove 60 °
Welding process MAG
Welding position PA
Groove preparation machining Groove cleaning
Fastening Edge fastener
Tack welding Accesory equipment
Back gouging Non
Electrode
Backing ring Fiberglass tape
Cutting-edge angle
Filler material and shielding gas Torch angle
0°
OK AUTROD 12.51 Elevated working temperature
Interpass temperature
Flow rate range Heating rate
Backing gas Soaking temperature
Flow rate range Soaking time
Type of current
Notes: Backing ring was woven glass Date and author: 07.04.2009 MPirinen
Bead Welding
Appendix 4.
Table 1 Characteristic of nonmetallic inclusions (Ramirez 2008).
Inclusion Characteristics
Inclusion Chemical Composition Description
1 Region A — 50.1O-0.7Mg-1.6Al-3.9Si-2.8S-19.6Ti-21.4Mn O, Al, Si, S, Ti, Mn rich
Region B — 48.2O-0.9Mg-1.6Al-3.4Si-2.3S-22.2Ti-21.4Mn
2 51.4O-1.4Al-4.5Si-1.7S-18.1Ti-22.8Mn O, Al, Si, S, Ti, Mn rich
3 Region A — 32.2O-0.5Al-1.3Si-0.9S-51.4Ti-13.7Mn (Ti-O2) Composite inclusion
Region b MnS, Region c Ti-Oxide
4 Region A — 32.3O-1.5Al-0.7Si-50.4Ti-15.1Mn Ti-Mn oxide
Region B — 35.4O-3.2Al-6.1Si-0.8S-26.5Ti-28.0Mn Region C — 35.3O-4.4Al-9.6Si-1.4S-3.6Ti-45.8Mn
5 30.9O-1.8Si-26.5S-3.5Ti-37.3Mn Mn, S, O rich
6 56.2O-1.3Al-5.5Si-2.1S-15.4Ti-19.5Mn Ti-Mn oxide
7 77.8O-0.9Si-1.3S-17.2Ti-2.8Mn O, Si, S, Ti, Mn rich
8 65.5O-0.5Si-1.4S-22.8Ti-9.8Mn Ti oxide
9 65.4O-2.5Si-13.0S-16.0Ti-3.1Mn O, S, Ti rich
10 67.9O-3.5Si-4.4S-21.1Ti-3.1Mn Ti Oxide
11 73O-1.9Al-6.9Si-1.0S-14.6Ti-2.7Mn O, Al, Si, Ti, Mn rich
12 55.1O-4.0Al-17.6Si-1.6S-3.6Ti-18.2Mn O, Si, Mn rich
13 55.9O-4.2Al-17.6Si-1.8S-2.4Ti-18.1 Mn O, Al, Si, Mn rich
14 Region A — 57.9O-4.6Al-17.4Si-1.9S-2.8Ti-15.5Mn Composite inclusion
Region B — 60.2O-1.7Al-2.2Si-0.6S-24.5-10.8
23 47.0C-14.4N-10.9O-1.2Mg-2.0Al-24.5Zr Zr Carbo-Nitride - Al2O3
24 Region A — 23.0N-1.9Mn-7.9Al-66.6Zr-0.7Ti; Composite inclusion
Region B — 39.9N-23.4O-1.0Mg-30.3Al-5.4Zr
25 45.4C-14.6N-15.6O-0.8Al-23.9Zr Zr Carbo-Nitride
26 40.3C-13.0N-13.4O-1.7Mg-2.8Al-28.7Zr Zr Carbo-Nitride
27 Region A — 40.4O-10.9Mg-23.0Al-25.7Zr Composite inclusion
Region B — 48.9O-15.0Mg-36.1Al
28 Region A — 20.8N-33.2O-1.7Mg-1.6Al-42.7Zr Composite inclusion
Region B — 79.5O-20.5Zr
Region A — 18.9N-29.2O-2.95Mg-3.0Al-46.0Zr Composite inclusion
Region B — 17.2N-40.8O-3.8Mg-13.9Al-24.3Zr
29 11.2N-50.6O-14.2Mg-19.6Al-4.4Zr Composite inclusion
30 62.7O-3.4Mg-2.0Al-31.92Zr O, Mg, Al, Zr rich
36 63.7O-5.3Al-5.2Si-11.1Ti-14.7Mn O, Al, Si, Ti, Mn rich
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