TY - JOUR A1 - Schaupp, Thomas A1 - Schröpfer, Dirk A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Welding residual stress distribution of quenched and tempered and thermo-mechanically hot rolled high strength steels JF - Advanced materials research N2 - Beside quenched and tempered (QT) high strength steels advanced technologies in steel manufacturing provide steels produced by the thermo-mechanical controlled process (TMCP) with yield strength of 960 MPa. These steels differ in the carbon and micro-alloying element content. With variation of heat control TIG-welded dummy seams on both steel types were performed. Analyses concerning microstructure and residual stress evolution due to welding showed typical stress distributions according to common concepts. Yet, the TMCP-steel shows higher residual stresses than the QT-steel. KW - Mill Scale KW - Quenched KW - Residual Stress KW - Tempered High Strength Steel KW - Thermo-Mechanical Controlled Process KW - Welding PY - 2014 DO - https://doi.org/10.4028/www.scientific.net/AMR.996.457 SN - 1022-6680 SN - 1662-8985 VL - 996 SP - 457 EP - 462 PB - Trans Tech Publ. CY - Zurich AN - OPUS4-31443 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brauser, Stephan A1 - Kromm, Arne A1 - Dabah, Eitan A1 - Kannengießer, Thomas A1 - Rethmeier, Michael T1 - Thermal stability of retained austenite in low alloyed TRIP-steel determined by high energy synchrotron radiation JF - Materials science forum N2 - TRIP-steels offer a good combination between strength and ductility. Therefore TRIP-steels are widely used in the automobile industries. The aim of this work is to study the stability of involved phases during heating and to identify the kinetics of the occuring phase transformations. For that purpose, in-situ diffraction measurements, using high energy synchrotron radiation were conducted. The analysis revealed the decomposition of the metastable austenitic phase into carbide and ferrite along the heating process and the regeneration of the austenite by further heating of the sample. KW - Austenite stability KW - Phase transformation KW - TRIP steel KW - Energy dispersive synchrotron X-ray diffraction PY - 2014 DO - https://doi.org/10.4028/www.scientific.net/MSF.772.129 SN - 0255-5476 VL - 772 SP - 129 EP - 133 PB - Trans Tech Publications CY - Aedermannsdorf, Switzerland AN - OPUS4-29700 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gibmeier, J. A1 - Obelode, E. A1 - Altenkirch, J. A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Residual stress in steel fusion welds joined using low transformation temperature (LTT) filler material JF - Materials science forum N2 - Welding residual stress is of major concern for structural integrity assessment in industrial components. Shear and volume strains resulting from the austenite-martensite-transformation affect the development of residual stress during welding. Controlling the phase transformation allows adjustment of the welding residual stress. Low transformation temperature (LTT) weld filler materials exhibiting reduced MS-temperatures allow postponing the phase transformation. The associated strain arising from the delayed transformation compensates for the thermal contraction strains and as such may reduce tensile or even introduce compressive residual stress. In this article we discuss the tri-axial residual stress distribution in 15 mm S690Q steel plates joined with LTT filler materials with 10 wt% Cr and a Ni-content that varies from 8 to 12 wt%. Using complementary synchrotron X-ray and neutron diffraction stress analysis the macroscopic residual stress was derived from the phase specific lattice strain and phase fraction of martensite and retained austenite, respectively. The local phase specific unstrained lattice parameters were determined using stress relieved combs. The investigation revealed increasing phase fraction of retained austenite with increasing Ni-content. Further, independent of the Ni-content in each weld in the fusion zone, significant compressive residual stresses were found in the longitudinal direction, which are balanced by tensile residual stresses in the heat affected zone (HAZ). In the weld transverse and normal direction the stress distribution is qualitatively similar but less in magnitude. The increased amount of retained austenite reduces the compressive stress arising from shear and volume strains during the delayed phase transformation and therefore no significant increase in compression was observed for decreasing MS-temperatures. KW - Welding residual stresses KW - Neutron diffraction KW - LTT filler materials PY - 2014 DO - https://doi.org/10.4028/www.scientific.net/MSF.768-769.620 SN - 0255-5476 VL - 768-769 SP - 620 EP - 627 PB - Trans Tech Publications CY - Aedermannsdorf, Switzerland AN - OPUS4-29706 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Effect of martensitic phase transformation on stress build-up during multilayer welding JF - Materials science forum N2 - Innovative low transformation temperature (LTT) welding filler materials are featuring a characteristic chemical composition which favors the formation of martensite at comparatively low temperatures. This permits deliberate adjustment of welding residual stresses. Even though numerous investigations can be found in the literature on this issue, they provide only little insight into the interaction between phase transformation and resulting welding residual stresses. For this purpose, a component weld test was performed in a special large-scale testing facility. The results illustrate that the desired residual stress control by using LTT alloys is actually feasible. With increasing shrinkage restraint, however, higher tensile residual stresses are formed in transverse direction of the weld. By contrast, the residual stress level in longitudinal weld direction is nearly independent of the restraint conditions. On-line stress analysis revealed that the amount of stress reduction during cooling of the individual weld runs is dependent on the weld volume undergoing phase transformation. Overall, evidence was furnished that the approach of residual stress engineering by LTT alloys is suitable even in the case of large-scale multilayer welding. KW - LTT KW - Martensite KW - Multilayer Welding KW - Phase Transformation KW - Residual Stress PY - 2014 DO - https://doi.org/10.4028/www.scientific.net/MSF.768-769.660 SN - 0255-5476 VL - 768-769 SP - 660 EP - 667 PB - Trans Tech Publications CY - Aedermannsdorf, Switzerland AN - OPUS4-29708 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Kromm, Arne A1 - Steppan, Enrico A1 - Kannengießer, Thomas ED - Kannengießer, Thomas ED - Babu, S. S. ED - Komizo, Y. ED - Ramirez, A.J. T1 - High-energy synchrotron study of the stress-strain behavior of hydrogen-charged high strength structural steel T2 - In-situ studies with photons, neutrons and electrons scattering II N2 - High strength structural steels are susceptible to hydrogen embrittlement. A critical combination of stress, amount of diffusible hydrogen and microstructure is believed to cause cold cracking. Especially during welding of high strength structural steels high tensile residual stresses may develop. Therefore, a feasibility study was conducted using synchrotron X-ray diffraction in order to analyze the stress–strain behavior during tensile loading. For that purpose two types of steel showing different hardening mechanisms were used. On the one hand a thermo-mechanically treated S1100MC and on the other hand a quenched and tempered S1300Q were chosen. The samples were electrochemically charged with hydrogen and subsequently stored in liquid nitrogen to prevent effusion. Tensile tests of the samples were conducted in a special load frame allowing for tilting the samples while applying constant loads. High energy synchrotron radiation was used for energy dispersive X-ray diffraction (EDXRD) analysis in transmission geometry. This method offers the possibility for measuring several diffraction lines of all contributing crystalline phases of the material. Strains as well as stresses applying the sin²ψ-method were determined for varying load situations. This feasibility study shows how the interaction of hydrogen and the stress/strain response may be assessed by diffraction methods. Examples are presented showing that hydrogen alters the load distribution as well as the strain behavior between different lattice planes in high strength steels. KW - High energy synchrotron radiation KW - Energy dispersive X-ray diffraction (EDXRD) KW - High strength structural steels KW - Tensile tests KW - Hydrogen embrittlement PY - 2014 SN - 978-3-319-06144-3 SN - 978-3-319-06145-0 DO - https://doi.org/10.1007/978-3-319-06145-0_10 SP - 165 EP - 176 PB - Springer AN - OPUS4-31356 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Stress Build-Up during Mulitlayer Welding with Novel Martensitic Filler Materials JF - HTM - journal of heat treatment and materials N2 - Neuartige sogenannte Low-Transformation-Temperature (LTT)- Schweißzusätze weisen eine chemische Zusammensetzung auf, welche die Martensitbildung zu vergleichsweise niedrigen Temperaturen verschiebt. Dies wirkt sich maßgeblich auf die nach dem Schweißen vorliegenden Eigenspannungen aus. Obwohl dazu zahlreiche Veröffentlichungen vorliegen, blieben die Wirkzusammenhänge zwischen Umwandlungstemperatur und Schweißeigenspannungen bislang ungeklärt. Aus diesem Grund wurde in der vorliegenden Arbeit ein Versuch in einer Großprüfanlage durchgeführt, um den Einfluss der Martensitumwandlung während des Mehrlagenschweißens zu analysieren. Die In-Prozess-Beobachtung der auftretenden Kräfte und Momente offenbarte, dass die Eigenspannungsreduktion vom jeweils umwandelnden Volumen abhängt. Die Analyse der Schweißeigenspannungen verdeutlichte, dass die angestrebte Eigenspannungsbeeinflussung durch den Zusatzwerkstoff stark von den Randbedingungen (d. h. Nahtaufbau, Blechdicke) abhängt und einer Bewertung im jeweiligen Anwendungsfall bedarf. N2 - 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. Innovative Low Transformation Temperature (LTT-) filler materials are specially designed for Controlling weld residual stresses by means of adjusted martensite formation already during welding. Numerous publications can be found on this issue, but they provide only little insight into the interaction between martensite formation and resulting welding residual stresses. Within this study a component weld test was performed in a special large-scale testing facility. In-situ load analysis revealed that the amount of stress reduction during deposition of the individual weld runs is dependent on the weld volume undergoing phase transformation related to the shrinking volume. The residual stresses found alter welding show that the desired residual stress control by using LTT alloys is sensitive to welding boundary conditions (i. e. weld geometry, plate thickness) and to be evaluated separately for varying weld scenarios. T2 - Spannungsentstehung während des Mehrlagenschweißens mit einem neuartigen martensitischen Schweißzusatz KW - Residual stresses KW - LTT filler material KW - Martensite KW - Phase transformation KW - Welding KW - Eigenspannungen KW - LTT-Zusatzwerkstoff KW - Martensit KW - Phasenumwandlung KW - Schweißen PY - 2014 DO - https://doi.org/10.3139/105.110210 SN - 2194-1831 SN - 1867-2493 VL - 69 IS - 2 SP - 80 EP - 88 PB - Hanser CY - München AN - OPUS4-30719 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gibmeier, J. A1 - Held, A. A1 - Altenkirch, J. A1 - Kromm, Arne A1 - Kannengießer, Thomas A1 - Buslaps, T. T1 - Real time monitoring of phase transformation and strain evolution in LTT weld filler material using EDXRD JF - Journal of materials processing technology N2 - For a newly developed 10% Cr and 10% Ni low transformation temperature (LTT) weld filler material, the local phase transformation kinetics and the strain evolution during gas tungsten arc welding (GTAW) under real welding conditions was studied. An experimental set-up and a measuring and evaluation strategy are presented to gain a real time insight into the welding process. The experiments were carried out at the beam line ID15@ESRF using a two detector EDXRD (energy dispersive X-ray diffraction) set-up and high energy synchrotron X-rays. The time-resolved diffraction analysis during welding was carried out locally throughout the weld in longitudinal as well as in transverse direction to the weld line to examine the interdependence of the strain state and the transformation kinetics. This comprehension is crucial for the optimization of the weld process, and thus for the tailoring of the resulting residual stress states, which is one of the main issues for the application of LTT alloys. Using the herein proposed approach EDXRD diffraction pattern can be monitored during real welding with a counting rate of 5 Hz. By means of the time resolved diffraction data the local transformation temperatures and times were determined and the local phasespecific strain evolutions are discussed with respect to the transformation rates and the time-delayed phase transformations. KW - In situ synchrotron X-ray diffraction KW - Low transformation temperature KW - Welding PY - 2014 DO - https://doi.org/10.1016/j.jmatprotec.2014.06.008 SN - 0924-0136 SN - 1873-4774 VL - 214 IS - 11 SP - 2739 EP - 2747 PB - Elsevier CY - Amsterdam AN - OPUS4-30955 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröpfer, Dirk A1 - Kannengießer, Thomas A1 - Kromm, Arne T1 - Influence of heat control on welding stresses in multilayer-component welds of high-strength steel S960QL JF - Advanced materials research N2 - Today high-strength structural steels (yield strength ≥ 960 MPa) are increasingly applied. Therefore, weldments have to achieve equal strength. Yet, high residual stresses in those welds diminish the components safety. Especially high restraint intensities can lead to crack-critical stress-levels. A special 2-MN-test facility allowed online-measurements of global reaction forces under defined restraint conditions during welding and cooling of multilayer-component MAG-welds. Local residual stresses were measured via X-ray diffraction before and after relief of the restraint. Local and global stresses were highly affected by heat control. KW - High-Strength Steel KW - Reaction Stress KW - Welding KW - X-Ray Diffraction (XRD) PY - 2014 DO - https://doi.org/10.4028/www.scientific.net/AMR.996.475 SN - 1022-6680 SN - 1662-8985 VL - 996 SP - 475 EP - 480 PB - Trans Tech Publ. CY - Zurich AN - OPUS4-31444 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kromm, Arne A1 - Dixneit, Jonny A1 - Kannengießer, Thomas T1 - Residual stress engineering by low transformation temperature alloys - state of the art and recent developments JF - Welding in the world N2 - Residual stress engineering in welding becomes more and more prominent as the use of tailored materials, e.g., high-strength steels, calls for maximum utilization of the material properties. As a consequence, residual stresses have to be considered as design criterion. Moreover, it may be utilized to improve the material's performance. Low transformation temperature alloys are a smart approach to control the residual stresses already during the welding process avoiding time-consuming postweld treatments. This paper gives an overview about the progress made in research in this topic with special focus on residual stresses. Basics as well as important developments will be addressed. KW - Residual stresses KW - Martensite KW - Low temperature KW - Transformation PY - 2014 DO - https://doi.org/10.1007/s40194-014-0155-6 SN - 0043-2288 SN - 1878-6669 VL - 58 IS - 5 SP - 729 EP - 741 PB - Springer CY - Oxford AN - OPUS4-31446 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - In-situ observation of stress accumulation during sub-merged arc welding JF - Advanced materials research N2 - Results obtained from laboratory tests mostly need to be verified under fabrication conditions in order to incorporate design specifics (joint configuration and restraint), which effect the residual stress state considerably. For this purpose, multi-pass sub merged arc welding was performed in a special large-scale testing facility. The impact of varying interpass temperatures could be proven in-situ by means of a pronounced stress accumulation during welding and subsequent heat treatment accompanied by stress determination using X-ray diffraction. KW - Heat Control KW - Sub-Merged Arc Welding KW - X-Ray Diffraction (XRD) PY - 2014 DO - https://doi.org/10.4028/www.scientific.net/AMR.996.417 SN - 1022-6680 SN - 1662-8985 VL - 996 SP - 417 EP - 423 PB - Trans Tech Publ. CY - Zurich AN - OPUS4-31448 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kannengießer, Thomas A1 - Kromm, Arne T1 - Moderne Methoden der Spannungsanalyse an geschweißten Komponenten T2 - 15. Sommerkurs Werkstoffe und Fügen am Institut für Werkstoff- und Fügetechnik N2 - Die experimentelle Spannungsanalyse dient einerseits zur Ermittlung von Materialeigenschaften, andererseits erlangt sie gerade für die wirtschaftliche Auslegung und die Integrität von geschweißten Komponenten zunehmend an Bedeutung. Da die Höhe und Veränderung von Bauteilbeanspruchungen und deren Auswirkung auf die Sicherheit von einer Vielzahl und sich überlagernder werkstofflicher, mechanischer und thermischer Einflussfaktoren (Steifigkeitsverhältnisse, Fertigungsprozesse, Lastwechsel) abhängt, sind fertigungs- bzw. betriebsbegleitende Messungen von mechanisch und thermisch bedingten Dehnungen und daraus ermittelten Spannungen oftmals unumgänglich. In geschweißten Komponenten sind oft komplexe Spannungs- bzw. Eigenspannungsverteilungen in den verschiedenen Raumrichtungen vorhanden. In Abhängigkeit vom anzusetzenden Tragfähigkeitsnachweis bzw. Berechnungskonzept des Tragwerkes sind sowohl experimentelle Methoden mit hoher Ortsauflösung (lokale Messungen) als auch mehrdimensionale Analysen über weite Bereiche des Bauteils (globale Messungen) von Dehnungen und Spannungen notwendig. T2 - 15. Sommerkurs Werkstoffe und Fügen am Institut für Werkstoff- und Fügetechnik CY - Magdeburg, Germany DA - 12.09.2014 PY - 2014 SN - 978-3-940961-85-3 SP - 27 EP - 34 AN - OPUS4-33469 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -