On Welding Residual Stresses Near Fatigue Crack Tips

Abstract:

Residual stresses in welded joints are supposed to change during fatigue loading. Residual stresses can be, depending on the loading conditions, relaxed as well as build up and they can be affected by fatigue crack growth. Furthermore residual stresses are supposed to affect the fatigue strength of welded steel structures. However, tensile residual stresses decrease and compressive residual stresses increase the fatigue strength. This residual stress effect on the fatigue strength is mostly explained with different crack propagation rates.The presented work is on welded longitudinal stiffeners, made of unalloyed fine grained carbon steel, with different fatigue crack lengths in which residual stresses have been determined. The residual stress measurement was conducted using Neutron diffraction. The results of the diffraction measurement show that the initial tensile residual stresses near the weld toe are, caused by phase transformation at low temperatures, below the base materials yield strength. Tensile residual stresses in the order of the yield strength can be found below the materials surface. These areas of high residual stresses are moving with the propagating crack tip through the specimen during fatigue loading.

• Periodical: Advanced Materials Research (Volume 996)
• Pages: 801-807
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.996.801
• Online since: August 2014
• Authors: Jonas Hensel*, Thomas Nitschke-Pagel, Klaus Dilger
• Keywords: Crack, Fatigue, Neutron Diffraction, Residual Stress, Welding

References

[1] G. Glinka, Effect of Residual Stresses on Fatigue Crack Growth in Steel Weldments Under Constant and Variable Amplitude Loads, in Fracture Mechanics, ASTM STP 677, C.W. Smith, Ed., American Society for Testing and Materials, 1979, pp.198-214.

DOI: 10.1520/stp34914s

[2] R. Galatolo & A. Lanciotti, Fatigue Crack Propagation in Residual Stress Fields of Welded Plates, International Journal of Fatigue, Vol. 19, Nr. 1, pp.43-49, (1997).

DOI: 10.1016/s0142-1123(96)00046-1

[3] C.D.M. Liljedahl, J. Brouard, O. Zanellato, J. Lin, S. Ganguly, P.E. Irving, M.E. Fitzpatrick, X. Zhang and L. Edwards, Weld Residual Stress Effects on Fatigue Crack Growth Behaviour of Aluminium Alloy 2024-T351, International Journal of Fatigue, Vol. 31, pp.1081-1088, (2009).

DOI: 10.1016/j.ijfatigue.2008.05.008

[4] C. Liljedahl, O. Zanellato, M. Fitzpatrick, J. Lin and L. Edwards, The Effect of Weld Residual Stresses and their Re-Distribution with Crack Growth during Fatigue under Constant Amplitude Loading, International Journal of Fatigue, Vol. 32, pp.735-743, (2010).

DOI: 10.1016/j.ijfatigue.2009.10.012

[5] J. Hensel, T. Nitschke-Pagel, K. Dilger & S. Schönborn, Effects of Residual Stresses on the Fatigue Performance of Welded Steels with Longitudinal Stiffeners, Materials Science Forum, Vols. 768-769, pp.636-643, (2013).

DOI: 10.4028/www.scientific.net/msf.768-769.636

[6] H. Wohlfahrt, Die Bedeutung der Austenitumwandlung für die Eigenspannungsentstehung beim Schweißen, Härtereitechnische Mitteilungen , Nr. 41, pp.248-257, 1986 (in German).

DOI: 10.1515/htm-1986-410507

[7] EN1993-1-1, Eurocode 3: Design of Steel Structures, Berlin: Beuth Verlag, (2010).

[8] A. Hobbacher, Recommendations for Fatigue Design of Welded Joints and Components, New York: Welding Research Council, (2009).

[9] T.R. Gurney, Fatigue of Welded Structures, 2nd Edition, Cambridge University Press, Cambridge, (1979).

[10] E. Macherauch & W. Reik, Auswirkung von Gefüge, Fertigung und Beanscpruchung auf das Dauerschwingverhalten, in Ermüdungsverhalten metallischer Werkstoffe, Oberursel, Deutsche Gesellschaft für Metallkunde e.V., pp.111-140, 1985 (in German).

[11] L. Edwards, Influence of Residual Stress Redistribution on Fatigue Crack Growth and Damage Tolerant Design, Materials Science Forum, Vols. 524-525, pp.363-372, (2006).

DOI: 10.4028/www.scientific.net/msf.524-525.363