PSI - Issue 68

Josef Arthur Schönherr et al. / Procedia Structural Integrity 68 (2025) 425–431 J. A. Scho¨nherr et al. / Structural Integrity Procedia 00 (2024) 000–000

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the creep stress power release rate. Therewith, the results of the ASTM E1457 method and Abaqus C t integral solution for steady-state creep are compared. The direct application of the Abaqus C t integral solution for steady-state creep leads to erroneous results for multi material specimens with di ff ering Norton exponent n . The ASTM E1457 method only accounts for a total of two materials, having a common value of n . If a momentous jump in the Norton exponent is su ffi ciently distant to the crack line, the ASTM E1457 method o ff ers a good agreement with creep stress power release rate evaluation results, if not, the results deviate. As pointed out, neglecting the HAZ properties may lead to miscalculations of C ∗ , especially if n varies over the particular material regions. Since cracks in the ICHAZ and FGHAZ are a common root of failures of welded components made from 9%-Cr steels, special care must be taken when calculating C ∗ . This research is part of a research project undertaken by the FVV e.V. and performed by the Materials Testing Institute (MPAS) at University of Stuttgart under the direction of Prof. Dr.-Ing. Stefan Weihe and by the Institute for Materials Technology (IfW) at TU Darmstadt under the direction of Prof. Dr.-Ing. Matthias Oechsner. The project is supported by the FVV expert group W14 “Creep crack growth” led by Dr.-Ing. Shilun Sheng (Siemens Energy). We gratefully acknowledge the support received from the chairman and from all members of the project user committee. Special thanks are due to the AVIF for funding the project under grant no. A324, foundation no. S0024 / 10270 / 21. Our sincere thanks also go to Dr.-Ing. Min Huang (MPAS) for her excellent cooperation in conducting the research project. ASTM E1457-19e1: “Standard Test Method for Measurement of Creep Crack Growth Times in Metals”, ASTM International, 2019, doi: 10.1520 / E1457-19E01. Dassault Systemes Simulia Corp. “SIMULIA User Assistance 2022 – Abaqus”, 2022. Fehe´r, A. “Ein Beitrag zur Qualifizierung und Simulation von Schweißverbindungen moderner Kesselbauwerksto ff e”. Dissertation, Technical University of Darmstadt, 2014. Francis, J. A., Mazur, W., Bhadeshia, H. K. D. H. “Review Type IV cracking in ferritic power plant steels”. Materials Science and Technology, vol. Kontermann, C., Almstedt, H., Mu¨ller, F., Oechsner, M. “On the Evaluation and Consideration of Fracture Mechanical Notch Support Within a Creep-Fatigue Lifetime Assessment”. Journal of Engineering for Gas Turbines and Power, vol. 140, no. 12, 2018, doi: 10.1115 / 1.4040733. Landes, J. D., Begley, J. A. “A Fracture Mechanics Approach to Creep Crack Growth”. Mechanics of Crack Growth, ASTM STP 590, American Society for Testing and Materials, 1976, pp. 128-148, doi: 10.1520 / STP33943S. Mayr, P. “Evolution of microstructure and mechanical properties of the heat a ff ected zone in B-containing 9% chromium steels”. Dissertation, Graz University of Technology, 2007. Rice, J. R., “A Path Independent Integral and the Approximate Analysis of Strain Concentration by Notches and Cracks”, ASME Journal of Applied Mechanics, vol. 35, no. 2, pp. 379–386, 1968, doi: 10.1115 / 1.3601206. Saxena, A., “Creep Crack Growth under Non-Steady-State Conditions”, in: ASTM STP905-EB: Fracture Mechanics: Seventeenth Volume, pp. 185 201, 1987, doi: 10.1520 / STP17396S. Zhou, H., Biglari, F., Davies, C. M., Mehmanparast, A., Nikbin, K. M. “Evaluation of fracture mechanics parameters for a range of weldment geometries with di ff erent mismatch ratios”, Engineering Fracture Mechanics, vol. 124-125, pp. 30-51, 2014, doi: 10.1016 / j.engfracmech.2014.03.006. Ewald, J., Sheng, S., Almstedt, H., Mu¨ller, F., Klenk, A., Scholz, A., Hobt, A. “Engineering Guide for Assessment of Creep Crack Initiation on Components by Two-Criteria-Diagram”, FVV R592, Forschungsvereinigung Verbrennungskraftmaschinen e.V., 2019. BS 7910:2019: “Guide to methods for assessing the acceptability of flaws in metallic structures”, British Standards Institution, 2019. Nikbin, K. M., Smith, D. J., Webster, G. A. “An Engineering Approach to the Prediction of Creep Crack Growth”, Journal of Engineering Materials and Technology, vol. 108, no. 2, pp. 186-191, 1986, doi: 10.1115 / 1.3225859. Saxena, A. “Creep and Creep-Fatigue Crack Growth”, International Journal of Fracture, vol. 191, no. 1, pp. 31-51, 2015, doi: 10.1007 / s10704-015 9994-4. 22, no. 12, pp. 1387–1395, 2006, doi: 10.1179 / 174328406x148778. Kienzler, R. “Konzepte der Bruchmechanik“. Verlag Vieweg, 1993. Acknowledgements References