TY - CONF A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Online-Observation of Martensite Formation by combined use of Synchrotron Diffraction and Dilatometry T2 - Proceedings of Visual-JW 2019 & WSE 2019 N2 - Welding residual stress engineering by means of an adjusted martensite phase transformation would be highly attractive as detrimental tensile residual stresses may be prevented already during welding without time and cost intensive post processing. The present study shows a synchrotron diffraction analysis of a martensitic steel subjected to thermo-mechanical load cycles. Experiments were conducted regarding the microstructural strain response during the austenite to martensite transformation. The strains are a function of the temperature and the specific loads applied during cooling. The relation between the transformation plasticity of the material, the amount of martensite formed and the arising strains can thus be assessed. The lattice plane specific strains were compared to experimental findings from (macro) dilatation tests. It is shown that the microscopic material behavior differs remarkably from the one observed on the macroscopic scale, what leads to characteristic residual stresses in the material. T2 - Visual-JW 2019 & WSE 2019 The 5th International Symposium on Visualization in Joining & Welding Science through Advanced Measurements and Simulation & The 8th International Conference of Welding Science and Engineering CY - Osaka, Japan DA - 21.11.2019 KW - Martensite KW - Synchrotron KW - Dilatometry KW - Residual stress KW - Phase transformation PY - 2019 SP - 83 EP - 84 PB - SEIEI Printing Co., Ltd CY - Osaka, Japan AN - OPUS4-49770 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dixneit, Jonny A1 - Kromm, Arne A1 - Boin, M. A1 - Kannengießer, Thomas A1 - Gibmeier, J. ED - Olden, T.-M. ED - Muransky, O. Muransky ED - Edwards, L. T1 - Influence of heat control on residual stresses in low transformation temperature (LTT) large scale welds T2 - Residual Stresses 2016: ICRS-10 N2 - The current paper presents residual stress analyses of large scale LTT (Low Transformation Temperature) welds. LTT filler materials are specially designed for residual stress engineering by means of an adjusted martensite phase transformation. Controlling the level of mostly detrimental residual stresses already during the welding process would be highly attractive as time and cost consuming post processing may be prevented. In large scale welds the residual stress state is influenced by the heat control (e.g. interpass temperature) during welding. Therefore, welding residual stresses are studied here putting the focus on the influence of welding process parameters while joining heavy steel sections with a thickness of 25 mm. The residual stress state was determined at the top surface using X-ray diffraction as well as in the bulk by neutron diffraction. The results show that control of the interpass temperature is vital for the residual stresses present in the joints. This accounts for the top surface but is most pronounced for the bulk of the welds. While high interpass temperatures are appropriate to induce compressive residual stresses in the weld metal, low interpass temperatures favor unwanted tensile residual stresses instead. T2 - ICRS 2016 - 10th International Conference on Residual Stresses CY - Sydney, Australia DA - 03.07.2016 KW - LTT KW - Welding residual stress KW - Phase transformation KW - Interpass temperature PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-389628 SN - 978-1-94529117-3 SN - 978-1-94529116-6 DO - https://doi.org/10.21741/9781945291173-38 SN - 2474-395X VL - 2 SP - 223 EP - 228 PB - Materials Research Forum LLC CY - Millersville (PA), USA AN - OPUS4-38962 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -