TY - JOUR A1 - Kannengießer, Thomas A1 - Kromm, Arne A1 - Rethmeier, Michael A1 - Gibmeier, J. A1 - Genzel, C. T1 - Residual stresses and in-situ measurement of phase transformation in low transformation temperature (LTT) welding materials JF - Advances in x-ray analysis PY - 2009 SN - 1097-0002 SN - 0069-8490 SN - 0376-0308 VL - 52 SP - 755 EP - 762 CY - Newtown Square, Pa., USA AN - OPUS4-19817 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kromm, Arne A1 - Kannengießer, Thomas A1 - Gibmeier, J. A1 - Genzel, C. A1 - Van der Mee, V. T1 - Determination of residual stresses in low transformation temperature (LTT -) welds metals using X-rayand high energy synchrotron radiation JF - Welding in the world N2 - Crack and fatigue resistance are relevant evaluation criteria for welded joints and are decreased by tensile residual stresses resulting from the welding and cooling process, while compressive residual stresses can have a positive influence on the characteristics mentioned. In order to generate compressive residual stresses, a set of post weld treatment procedures is available, like shot peening, hammering, etc. These procedures have the disadvantage that they are time and cost extensive and have to be applied after welding. As another point, such technologies can only produce compressive stresses at the top surface, i.e. can only contribute to the reduction of the risk of cracks initiated at the surface, like fatigue cracks. A chance to generate compressive stresses over the complete weld joint during the welding procedure is offered by the so-called Low Transformation Temperature (LTT -) filler wires. Compared to conventional wires, these materials show lower phase transformation temperatures, which can work against coolingrelated tensile stresses, resulting from respective shrinkage restraint. In consequence, distinct compressive residual stresses can be observed within the weld and adjacent areas. The strength of these fillers makes them potentially applicable to high-strength steel welding. Welds produced with different LTT – filler wires have shown different levels and distributions of the resulting residual stresses depending on the specific transformation temperature. The transformation temperatures are determined by temperature measurement. Classical X-ray diffraction as well as diffraction methods using high energy synchrotron radiation have been used for residual stress analysis. By means of high energy synchrotron diffraction in reflection mode residual stress depth gradients can be determined nondestructively. The phase selective nature of the diffraction measurements enables the simultaneous determination of the phase specific residual stresses of all contributing crystalline phases within one experiment. The application of white beam diffraction implies recording of a multitude of diffraction lines within the energy range of the provided energy spectrum of the white beam. By this means phase specific residual stress depth distributions up to distances of 150 ìm below the surface can be analysed for steel using the energy dispersive set-up of the HMI-beamline EDDI at the Bessy site, Berlin, providing an energy range between 20-150 keV. As a side effect quantitative phase analysis can be carried out using white energy dispersive diffraction e.g. the determination of the content of retained austenite in the weld. KW - Filler materials KW - Low temperature KW - Reference lists KW - Residual stresses KW - Temperature KW - Transformation KW - Synchrotron radiation KW - Phase specific residual stresses KW - Energy dispersive diffraction PY - 2009 SN - 0043-2288 SN - 1878-6669 VL - 53 IS - 1/2 SP - 3 EP - 16 PB - Springer CY - Oxford AN - OPUS4-19214 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -