Festigkeitskonzepte geschweißter Bauteile - Gelenkwelle aus Stahl

FKM 2009
Issue number 301
Project no. 273

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Final report
Abstract:

Fatigue strength tests were carried out on welded pipe and flat specimens made of the heat-treatable steel 42CrMo4 in combination with the structural steel S355J2G3 under rotating bending and torsion or tensile compression at constant and variable amplitudes. The influence of two different weld seam geometries and different
welding processes was investigated. The evaluation is carried out in a comparison with the nominal, structural and notch stress concept and a comparison of the results with
the IIW recommendations for the fatigue strength of welded components. In addition, fracture mechanical material parameters were determined on welded specimens.
For pipe and flat specimens, the fatigue strength of the modified internally centered butt joint (mSS) is greater than that of the conventional internally centered butt joint
(kSS). According to the nominal stress concept, the fatigue strength of the laser-welded flat specimens is greater than that of the TIG-welded specimens. The fracture mechanics investigations
show higher crack toughness values and lower crack propagation rates for laser-welded specimens compared to TIG-welded specimens.
For the investigations presented here, the application of the nominal stress concept is particularly recommended for the different types of flat orbits. A differentiation
between welding process and ~ahkeometry'is not possible. The notch stress concept with rWf=0.05 mm is recommended for ~ohr~robes under bending, as it can be used to demonstrate the
increase in fatigue strength of the mSS variant compared to the kSS variant, even if the conservatism of the service life prediction does not decrease significantly compared to the statements
of the nominal and structural stress concept. Using the notch stress concept with an equivalent radius of r=1.0 mm does not make sense with a welded
sheet thickness of 5.5 mm. This is also shown by the reference radius r,=0.3 mm for the pipe samples under bending. It was shown that it is possible to apply
the structural stress concept to root cracks. The objective of the research project has been achieved. Scope of report:
152 pages Start of work:
01.09.2005 End of work:
31.10.2008 Funding body:
BMWi i AiF-Nr. 1451 8 N Research center:
Institute of Materials Science and State Materials Testing Institute of TU Darmstadt Head:
Prof.Dr.-lng. C. Berger Processor and author:
Dr.-lng. B. Pyttel Chairman of the working group:
Dipl.-lng. P. Grawenhof, Voith Turbo GmbH & Co. KG, Heidenheim Chairman of the Advisory Board:
Dipl.-lng. H. Linn, LlNN HIGH THERM GmbH, Hirschbach