journal article·2025-08Open access

The severity of local undercut on fatigue life of welded joints

Abinab Niraula, Heikki Remes

Abstract

Fatigue cracks most commonly initiate from local weld imperfections, such as undercuts, that have a significant impact on the fatigue life of the structure. The influence of local undercut on fatigue has been traditionally classified on the level of workmanship for quality control purposes, and a systematic quantified approach to determine the influence of local undercut on fatigue strength is needed. In this paper, the influence of the 3D undercut geometry on the fatigue strength of welded joints is investigated to quantify the severity of different undercut sizes and shapes in butt welded joints. Systematic elastic and elasto-plastic analyses are performed on butt-welded joints with different steel grades and local undercut geometries under multiple stress ranges. As a result, a semi-analytical formulation is proposed to estimate the elastic stress concentration factor for butt welds with an undercut, considering the 3D undercut geometry as well as the global weld geometry. Furthermore, a novel undercut severity index for fatigue analysis is introduced and validated, considering the variation of the local undercut 3D shape, weld bead geometry, stress ranges, and materials.
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Research context

OpenAlex topics: Fatigue and fracture mechanics · Material Properties and Failure Mechanisms · Advanced Welding Techniques Analysis

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References (58)

Show source-provided references
1. 5 - Notch strain approach for seam-welded joints
2. Fatigue Crack Initiation and Propagation in High Yield-Strength Steel Weld Metal
3. High strength and high performance steels and their use in bridge structures10.1016/S0143-974X(01)00028-1 ↗
4. Fatigue strength prediction of ultra high strength steel butt-welded joints10.1111/ffe.12015 ↗
5. Dowling · 2013 · 417
6. Differences in Fatigue Strength Between Arc and Laser Hybrid Welded Joints10.5957/jsp.2008.24.3.139 ↗
7. Lillemäe-Avi I, Remes H, Dong Y, Garbatov Y, Quemener Y, Eggert L, et al. Benchmark study on considering welding-induced distortion in structural stress analysis of thin-plate structures. Progress in the Analysis and Design of Marine Structures - Proceedings of the 6th International Conference on Marine Structures, MARSTRUCT 2017, 2017, p. 387–94. doi: 10.1201/9781315157368-45.10.1201/9781315157368-50 ↗
8. Effect of weld geometric profile on fatigue life of cruciform welds made by laser/GMAW processes10.1016/j.marstruc.2006.07.002 ↗
9. Factors affecting the fatigue strength of thin-plates in large structures10.1016/j.ijfatigue.2016.11.019 ↗
10. Local weld geometry-based characterization of fatigue strength in laser-MAG hybrid welded joints10.1007/s40194-023-01488-5 ↗
11. Undercuts in Laser Arc Hybrid Welding10.1016/j.phpro.2014.08.071 ↗
12. Laser-arc hybrid welding of 12- and 15-mm thick structural steel10.1007/s00170-020-05192-2 ↗
13. The effect of the local and global weld geometry as well as material defects on crack initiation and fatigue strength10.1016/j.engfracmech.2017.07.001 ↗
14. imo.org. Reducing Greenhouse Gas Emissions From Ships. 2019. http://www.imo.org/en/MediaCentre/HotTopics/Pages/Reducing-greenhouse-gas-emissions-from-ships.aspx (accessed September 16, 2020).
15. ISO 5817:2023 - Welding — Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding excluded) — Quality levels for imperfections n.d. https://www.iso.org/standard/80209.html (accessed November 18, 2024).
16. ISO standard. ISO 12932:2013. Welding — Laser-arc hybrid welding of steels, nickel and nickel alloys — Quality levels for imperfections. 2013:25.
17. ISO 13847:2013. Petroleum and natural gas industries — Pipeline transportation systems — Welding of pipelines. ISO 2013. https://www.iso.org/standard/45120.html (accessed December 13, 2023).
18. Strain-based analysis on the influence of local undercut geometry on fatigue crack initiation life10.1016/j.ijfatigue.2024.108392 ↗
19. Influence of three-dimensional weld undercut geometry on fatigue-effective stress10.1007/s40194-018-0658-7 ↗
20. Characterisation of actual weld geometry and stress concentration of butt welds exhibiting local undercuts10.1016/j.engstruct.2021.112266 ↗
21. Peterson · 1953
22. Analytical and graphical aids for the fatigue design of weldments10.1111/j.1460-2695.1985.tb00424.x ↗
23. New parametric equations to estimate notch stress concentration factors at butt welded joints modeling the weld profile with splines10.1016/j.engfailanal.2016.11.006 ↗
24. Extended parametric equations for weld toe stress concentration factors and through-thickness stress distributions in butt-welded plates subject to tensile and bending loading10.1007/s40194-016-0377-x ↗
25. Parametric formulae for elastic stress concentration factor at the weld toe of distorted butt-welded joints
26. Stress concentration effects of undercut defect and reinforcement metal in butt welded joint10.1016/j.engfailanal.2009.10.010 ↗
27. Statistics of weld geometry for laser-hybrid welded joints and its application within notch stress approach10.1007/BF03263505 ↗
28. Fatigue experiment and assessment of butt-welded joints in steel structures considering misalignment and weld geometry effects10.1016/j.ijfatigue.2024.108200 ↗
29. The significance of weld toe undercuts in the fatigue of steel plate T-joints10.1016/0142-1123(89)90041-8 ↗
30. An Investigation of Influencing Factors on Bending Fatigue Strength of Fillet Welded Joint10.2534/jjasnaoe1968.1978.434 ↗
31. The Influence of Undercut on the Fatigue Strength of Welds: A Literature Survey
32. Influence of undercuts on the fatigue strength of butt welds
33. The effect of undercut, misalignment and residual stresses on the fatigue behaviour of butt welded joints10.1111/j.1460-2695.1996.tb01321.x ↗
34. Remes H. Strain-Based Approach to Fatigue Strength Assessment of Laser-Welded Joints. Espoo: TKK Dissertations 102; 2008.
35. Microstructural, mechanical, and fracture mechanical characterization of SA 508-Alloy 182 dissimilar metal weld in view of mismatch state10.1016/j.ijpvp.2016.06.004 ↗
36. The roles of yield strength mismatch, interface strength, and plastic strain gradients in fatigue crack growth across interfaces10.1016/j.engfracmech.2020.107072 ↗
37. Niraula A, Rautiainen M, Niemelä A, Lillemäe-Avi I, Remes H. Influence of weld-induced distortions on the stress magnification factor of a thin laser-hybrid welded ship deck panel. Trends in the Analysis and Design of Marine Structures - Proceedings of the 7th International Conference on Marine Structures, MARSTRUCT 2019, 2019, p. 423–32. doi: 10.1201/9780429298875-49.10.1201/9780429298875-49 ↗
38. Strain-controlled fatigue properties of steels and some simple approximations10.1016/S0142-1123(00)00026-8 ↗
39. A method of predicting cyclic stress–strain curve from tensile properties for steels10.1016/j.msea.2012.07.024 ↗
40. Fatigue properties of as-welded and post-weld-treated high-strength steel joints: The influence of constant and variable amplitude loads10.1016/j.ijfatigue.2020.105687 ↗
41. Fatigue strength modelling of high-performing welded joints10.1016/j.ijfatigue.2020.105555 ↗
42. Strain-based approach to fatigue crack initiation and propagation in welded steel joints with arbitrary notch shape10.1016/j.ijfatigue.2013.03.006 ↗
43. EBSD characterisation of grain size distribution and grain sub-structures for ferritic steel weld metals10.1007/s40194-021-01225-w ↗
44. CSC – IT Center for Science. High Performance Computing - Services for Research - CSC Company Site 2023. https://research.csc.fi/csc-s-servers (accessed December 20, 2023).
45. Garcia · Multiaxial fatigue analysis of high-strength steel welded joints using generalized local approaches · 2020
46. Influence of surface integrity on short crack growth behavior in HFMI-treated welded joints
47. Hartloper AR, de Castro e Sousa A, Lignos DG. Constitutive Modeling of Structural Steels: Nonlinear Isotropic/Kinematic Hardening Material Model and Its Calibration. Journal of Structural Engineering 2021;147. doi: 10.1061/(ASCE)ST.1943-541X.0002964.10.1061/(ASCE)ST.1943-541X.0002964 ↗
48. Consistency in Solving the Inverse Problem of the Voce-Chaboche Constitutive Model for Plastic Straining
49. Petry · 2022
50. Material characterization of high-frequency mechanical impact (HFMI)-treated high-strength steel10.1016/j.matdes.2015.10.001 ↗
51. The significance of weld imperfections and surface peening on fatigue crack propagation life of butt-welded joints10.1016/j.jmatprotec.2004.04.150 ↗
52. Fatigue strength assessment of butt-welded joints with undercuts10.1016/j.ijfatigue.2017.09.011 ↗
53. Influence of the shape of undercut on the fatigue strength of fillet welded assemblies - application of the local approach
54. Hobbacher · 2016
55. Applicability of fracture mechanics to very small cracks or the cracks in the early stage
56. Influence of surface integrity on the fatigue strength of high-strength steels10.1016/j.jcsr.2013.06.003 ↗
57. Influence of parent metal strength on the fatigue strength of parent material with machined and thermally cut edges10.1007/BF03266656 ↗
58. Investigating the impact of weld dilution and local mismatch on the low-cycle fatigue failure of Alloy 182 dissimilar weld transition under intermediate isothermal condition10.1016/j.engfailanal.2023.107112 ↗