TY - JOUR A1 - Schempp, Philipp A1 - Cross, Carl Edward A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - Influence of Ti and B additions on grain size and weldability of aluminium alloy 6082 N2 - Grain refinement is an important possibility to enhance the weldability of aluminium weld metal that is usually defined by its susceptibility to solidification cracking. In this study, grain refinement was achieved through the addition of commercial grain refiner containing titanium and boron to the GTA weld metal of aluminium alloy 6082. The weld metal mean grain size could be reduced significantly from about 70 µm to a saturated size of 21 µm with a change in grain shape from columnar to equiaxed. The grain refinement prevented the formation of centreline solidification cracking that was present only in welds with unrefined grain structure. A variation of torch speed led to a strong change of solidification parameters such as cooling rate that was measured in the weld metal and the corresponding solidification rate and thermal gradient. The ratio thermal gradient/growth rate (G/R) decreased from 50 K s/mm² (high torch speed) to 10 K s/mm² (low torch speed). However, the variation of torch speed did not change the tendency for solidification cracking. The microstructure of unrefined and completely refined weld metal was compared. The observed change in size and distribution of the interdendritic phases was related to the change in susceptibility to solidification cracking. KW - Aluminium KW - WIG-Schweißen KW - Kornfeinung KW - Schweißeignung KW - Heißrisse KW - Aluminium alloy KW - Solidification cracking KW - Weldability KW - GTA welding PY - 2012 SN - 0043-2288 SN - 1878-6669 VL - 56 IS - 09/10 SP - 95 EP - 104 PB - Springer CY - Oxford AN - OPUS4-26992 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cross, Carl Edward A1 - Eliezer, Dan A1 - Böllinghaus, Thomas T1 - The Role of Hydrogen in Titanium Alloy Weldments T2 - Titanium Conference 2006 CY - San Diego, CA, USA DA - 2006-10-01 PY - 2006 VL - 22 SP - 1 EP - 9 CY - San Diego AN - OPUS4-14488 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ben-Hamu, G. A1 - Eliezer, D. A1 - Cross, Carl Edward A1 - Böllinghaus, Thomas T1 - The relation between microstructure and corrosion behavior of GTA welded AZ31B magnesium sheet N2 - Welding of AZ31B magnesium alloy was carried out using gas-tungsten arc (GTA) welding. The microstructure and the corrosion behavior of welded magnesium AZ31B alloy were investigated. ac and dc polarization tests were carried out on the welded Mg sheet. The microstructure was examined using optical and electron microscopy (TEM and SEM), X-ray analysis and EDS. Scanning Kelvin probe force microscopy (SKPFM) was used in order to measure the Volta potential of different phases relative to the matrix. The results showed that the GTA process effected both the microstructure and the corrosion behavior. These results can be explained by the effects of the process on microstructure of AZ31B Mg alloy sheet such as grain size and precipitates caused by the change in precipitation and recrystallization behavior. KW - AZ31B KW - GTA weld KW - Microstructure KW - Corrosion behavior KW - SKPFM KW - Intermetallics PY - 2007 DO - https://doi.org/10.1016/j.msea.2006.12.122 SN - 0921-5093 SN - 1873-4936 VL - 452/453 SP - 210 EP - 218 PB - Elsevier CY - Amsterdam AN - OPUS4-15459 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cross, Carl Edward A1 - Böllinghaus, Thomas T1 - The Effect of Restraint on weld Solidification Cracking in Aluminium T2 - IIW Conference 2005 CY - Prague, Czech Republic PY - 2005 PB - IIW CY - Prag AN - OPUS4-11857 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Eliezer, Dan A1 - Hamu, G.B. A1 - Cross, Carl Edward A1 - Böllinghaus, Thomas ED - Galloway, T. T1 - Effect of grain refinement on the strength and corrosion of AZ31 magnesium alloy following severe plastic deformation N2 - Gas tungsten arc welds made on wrought magnesium AZ31 plate have been characterized for corrosion in saline solution (3.5% NaCl). Microstructural changes induced by the welding process resulted in different environmental behaviour of each zone (BM-base metal, HAZ-heat affected zone and FZ-fusion zone). The faster kinetics of corrosion in FZ and especially HAZ are attributed to (a) the coarse microstructure, consisting of large grains, and (b) very small amounts of ß-phase in the grain boundaries. Also, hardness traverses have shown that these zones are weaker than the base metal. Based on the significant effect of grain size on strength in magnesium alloys, the weld metal grains have been systematically refined using controlled oscillation during welding, and by adding a grain refiner to the weld pool. Detailed microstructure analyses have been carried out and the relationships between corrosion behaviour, mechanical properties and microstructure (grain refinement and second-phases formation) are highlighted. T2 - 135th Annual Meeting of the Minerals, Metals & Materials Society CY - San Antonio, TX, USA DA - 2006-03-12 PY - 2006 SN - 978-0-87339-619-6 VL - 135 SP - 1 EP - 4 PB - TMS, the Minerals, Metals & Materials Society CY - Warrendale AN - OPUS4-14452 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eliezer, Dan A1 - Tal-Gutelmacher, E. A1 - Cross, Carl Edward A1 - Böllinghaus, Thomas T1 - Hydrogen trapping in beta-21S titanium alloy N2 - Different characteristics of hydrogen's absorption/desorption behavior and trapping in ß-21S titanium alloy are studied by means of thermal desorption spectroscopy (TDS). Spectra analysis is supported by data from variety of other experimental techniques, such as LECO hydrogen determinator, XRD and microstructure investigations by means of optic and electronic microscopy. In contrast to many past considerations, the complex process of hydrogen evolution has been found to be significantly affected by the way hydrogen introduction into the alloy. The different trapping sites, as well as phase transformations, have to be considered as the reasons for the different hydrogen evolution behavior. KW - Titanium alloys KW - Hydrogen absorption KW - Hydrogen desorption KW - Thermally activated processes KW - Thermal desorption spectroscopy (TDS) PY - 2006 DO - https://doi.org/10.1016/j.msea.2006.01.067 SN - 0921-5093 SN - 1873-4936 VL - 421 IS - 1-2 SP - 200 EP - 207 PB - Elsevier CY - Amsterdam AN - OPUS4-14423 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eliezer, Dan A1 - Tal-Gutelmacher, E. A1 - Kannengießer, Thomas A1 - Cross, Carl Edward A1 - Böllinghaus, Thomas T1 - The effects of high fugacity and internal hydrogen on beta-21S titanium alloy T2 - EUROCORR 2005 CY - Lisbon, Portugal DA - 2005-09-04 KW - Titanium alloys KW - Beta-21S KW - Hydrogen desorption KW - Thermal Desorption Spectroscopy (TDS) PY - 2005 SP - 1 EP - 9 PB - Fundação para a Ciência e a Tecnologia CY - Lisbon AN - OPUS4-14451 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ben-Hamu, G. A1 - Eliezer, Dan A1 - Cross, Carl Edward A1 - Böllinghaus, Thomas T1 - Microstructure and Corrosion Resistance of TIG Welded AZ31B Magnesium Sheet T2 - 2nd International Conference on Magnesium CY - Beijing, China DA - 2006-06-25 KW - AZ31B KW - TIG welded KW - Microstructure KW - Corrosion behavior PY - 2006 VL - 2 IS - A-044 SP - 1 EP - 8 CY - Beijing AN - OPUS4-14486 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cross, Carl Edward A1 - Böllinghaus, Thomas T1 - The Effect of Restraint on weld Solidification Cracking in Aluminium KW - Aluminium alloys KW - Light metals KW - Solidification cracking KW - Cracking KW - Defects KW - Hot cracking KW - Crack initiation KW - Strain KW - Restraint PY - 2006 SN - 0043-2288 SN - 1878-6669 VL - 50 IS - 11/12 SP - 51 EP - 54 PB - Springer CY - Oxford AN - OPUS4-14220 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Cross, Carl Edward A1 - Coniglio, Nicolas A1 - Schempp, Philipp A1 - Mousavi, M.G. ED - Lippold, J. ED - Böllinghaus, Thomas ED - Cross, C.E. ED - et al., T1 - Critical conditions for weld solidification crack growth N2 - The occurrence of solidification cracking during welding remains a little understood phenomenon, in spite of extensive studies and tests performed to evaluate and compare the relative weldability of many different alloys. From an approach often adopted in the welding community attributed to Prokhorov, solidification cracks are believed to form when a critical tensile strain is exceeded, specific to the alloy, assuming that the mushy-zone has limited ductility. Tensile stresses and strains normally form behind a moving weld pool as a result of solidification shrinkage and thermal contraction, as influenced by welding parameters and the degree of restraint. KW - Solidification cracking KW - Aluminium alloy KW - Crack growth KW - Strain rate model PY - 2011 SN - 978-3-642-16863-5 DO - https://doi.org/10.1007/978-3-642-16864-2_2 IS - Part 2 SP - 25 EP - 41 PB - Springer CY - Berlin, Heidelberg AN - OPUS4-23846 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ben-Hamu, G. A1 - Eliezer, D. A1 - Cross, Carl Edward A1 - Böllinghaus, Thomas T1 - Volta potential of second phase particles in TIG welded AZ31 magnesium sheet T2 - EUROCORR 2006 CY - Maastricht, The Netherlands DA - 2006-09-25 KW - TIG welding KW - AZ31 Magnesium Alloy KW - Corrosion behavior PY - 2006 N1 - Serientitel: EFC-Event – Series title: EFC-Event IS - 280 SP - 1 EP - 10 PB - European Federation of Corrosion CY - Maastricht AN - OPUS4-22134 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eliezer, Dan A1 - Tal-Gutelmacher, E. A1 - Cross, Carl Edward A1 - Böllinghaus, Thomas T1 - Hydrogen absorption and desorption in a duplex-annealed Ti-6Al-4V alloy during exposure to different hydrogen-containing environments N2 - Based on its excellent combination of a high strength/weight ratio and good corrosion behavior, Ti–6Al–4V alloy is ranked among the most important advanced materials for a variety of industrial applications. However, in many of these technological applications, this alloy is exposed to environments which can act as sources of hydrogen, and severe problems may arise based on its susceptibility to hydrogen embrittlement. Even small hydrogen concentrations might lead to failure. Consequently, a comprehensive knowledge of hydrogen's absorption/desorption behavior and interactions between hydrogen and different microstructural features is necessary to better understand the desorption and trapping mechanisms, the types of the trap sites, and the trapped hydrogen content, in order to determine the safe service conditions of this alloy in the industry. In this paper, different characteristics of hydrogen's absorption/desorption behavior and trapping in a duplex-annealed Ti–6Al–4V alloy are studied by means of thermal desorption spectroscopy (TDS). Spectra analysis is supported by data from a variety of other experimental techniques, such as LECO hydrogen determinator, XRD and microstructure investigations by means of optical and electron microscopy. Hydrogen evolution is found to be a very complex process, being affected by the way hydrogen was initially introduced to the alloy, the phase transformations that may occur during the thermal analysis and the presence of potential trapping sites. KW - Titanium alloys KW - Hydrogen absorption KW - Hydrogen desorption KW - Ti-6Al-4V KW - Thermal desorption spectroscopy (TDS) PY - 2006 DO - https://doi.org/10.1016/j.msea.2006.06.088 SN - 0921-5093 SN - 1873-4936 VL - 433 IS - 1-2 SP - 298 EP - 304 PB - Elsevier CY - Amsterdam AN - OPUS4-14484 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Cross, Carl Edward A1 - Coniglio, Nicolas ED - Carl E. Cross, ED - John C. Lippold, ED - Böllinghaus, Thomas ED - Herold, H. T1 - Weld solidification cracking: critical conditions for crack initiation and growth N2 - A perspective will be given that outlines important considerations in evaluating and predicting weldability. An examination will be made of the local conditions necessary for solidifications crack initiation and growth in a weld. This will be done in light of two prominent thermo-mechanical approaches involving critical strain and critical strain rate. Critical conditions will be identified based upon values available in the literature. Methods used to measure strain and strain rate will be compared. The interpretation of crack lenght measurements commonly used to quantify weldability will be questioned, based upon our current understanding of the problem. Complications and problem areas needing better definition will be identified and discussed, including strain distribution in the mushy zone, segregation at grain boundaries, effect of impurities, and effect of cooling rate on solidification path. Finally, a suggestion will be made for a new approach to weld development using in-situ strain rate measurements and new composition-strain rate maps that define the boundary between crack an no-crack conditions. T2 - Hot cracking phenomena in welds II CY - Berlin, Germany DA - 2007-03-05 KW - Solidification Cracking KW - Hot Cracking KW - Crack Initiation KW - Crack Growth KW - Critical Strain KW - Critical Strain Rate KW - Weldability Testing KW - Crack Prediction PY - 2008 SN - 978-3-540-78627-6 SP - 39 EP - 58 PB - Springer CY - Berlin AN - OPUS4-18319 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Coniglio, Nicolas A1 - Cross, Carl Edward ED - Carl E. Cross, ED - John C. Lippold, ED - Böllinghaus, Thomas ED - Herold, H. T1 - Weld parameter and minor element effects on solidification crack initiation in Aluminium N2 - Earlier work has established that a critical amount of 4043 filler is required to avoid solidification cracking when arc-welding 6060 aluminium, depending upon local strain conditions. For example, when the mushy zone behind the weld pool experiences a tensile strain from combined thermal and shrinkage stresses, the possibility exists for crack initiation. For a greater rate of strain, it has been determined that a greater 4043 dilution (i.e. higher weld metal silicon content) is required to avoid crack initiation. Making use of the Controlled Tensile Weldability (CTW) test and local strain extensometer measurements, a boundary has been established between crack and no-crack conditions for different local strain rates and filler dilutions, holding all other welding parameters constant. Using this established boundary as a line of reference, additional parameters have now been examined and their influence on cracking has been characterized. These parameter influences have included studies of weld travel speed, weld pool contaminants (Fe, O, and H), and grain refiner additions (TiAl3 + Boron). Each parameter has been independently varied and its effect on cracking susceptibility quantified in terms of a critical strain rate required to initiate cracking for a given 4043 filler dilution. T2 - Hot cracking phenomena in welds II CY - Berlin, Germany DA - 2006-03-05 KW - Aluminium Alloys KW - Solidification Cracking KW - Weld Defect KW - Hot Cracking KW - Crack Initiation KW - Critical Strain Rate KW - Parameter Effects KW - Minor Elements PY - 2008 SN - 978-3-540-78627-6 SP - 277 EP - 310 PB - Springer CY - Berlin AN - OPUS4-18323 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -