TY - JOUR A1 - Glowacka, A. A1 - Nolze, Gert A1 - Swiatnicki, W. A. T1 - EBSD study of corrosion fatigue of austenitic-ferritic steel JF - Archives of Metallurgy and Materials N2 - Fatigue crack propagation investigations have been performed in austenitic-ferritic duplex stainless steel H22N5M3 in air and during hydrogen charging, using various frequencies of loading. Strong differences of crack propagation velocity depending on the test conditions were noticed. Lower frequency with applied hydrogen charging led to the huge increase of crack propagation velocity compared to the tests performed in air. To understand such a behaviour in each case and characterize crack mode, the samples were observed using electron back-scattered diffraction (EBSD). It was shown that in air, the fatigue crack propagation involved plastic deformation and the resulting cracks had ductile character. The presence of hydrogen led to more brittle mode of cracking. This effect was also connected with frequency of loading: lower frequency, which assured longer time for hydrogen-crack tip interaction, resulted in the highest crack propagation velocity and the brittle cracking mode with lower amount of plastic deformation. The performed observations indicated that the path of the crack went mostly transgranularly through both austenite and ferrite phases. Phase and grain boundaries were not the preferred paths for crack propagation. KW - Hydrogen KW - Embrittlement KW - Electron backscatter diffraction KW - Steel PY - 2006 SN - 1733-3490 SN - 0004-0770 SN - 0860-7052 VL - 51 IS - 1 SP - 7 EP - 10 AN - OPUS4-38029 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wendt, U. A1 - Nolze, Gert A1 - Heyse, H. T1 - Effect of crystal orientation on imaging contrast and sputter results during focused ion beam milling of Cu studied by FIB, EBSD, SEM, and AFM JF - Microscopy and Microanalysis N2 - During focused ion beam microscopy (FIB) of crystalline materials imaging contrast and milling result are effected by orientation of the crystals with respect to the incident ion beam. This is due to the possibility of ion channeling along preferred crystal directions which effects the depth at which interaction between ions and specimen atoms takes place. As a result of channeling emission of ion induced secondary electrons (iiSE) and secondary ions (SI) as well as the sputter rate decreases. Theoretical channeling orientations and critical angles can be calculated. These effects have been studied quantitatively for polycrystalline recrystallized Cu as a typical model case. KW - Electron backscatter diffraction KW - FIB KW - AFM KW - Crystal orientation PY - 2006 DO - https://doi.org/10.1017/S1431927606061812 SN - 1431-9276 SN - 1435-8115 VL - 12 IS - Suppl. 2 SP - 1302 EP - 1303 AN - OPUS4-38027 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Glowacka, A. A1 - Wozniak, M. J. A1 - Nolze, Gert A1 - Swiatnicki, W. A. T1 - Hydrogen induced phase transformations in austenitic-ferritic steel JF - Solid State Phenomena N2 - The hydrogen influence on the microstructure of the austenitic-ferritic Cr22-Ni5-Mo3 stainless steel was investigated. Cathodic hydrogen charging was performed electrochemically from aqueous solution of 0.1M H2SO4 with hydrogen entry promoter addition. The aim of this study was to reveal microstructural changes appearing during the hydrogen charging and particularly to clarify the occurrence of phase transformations induced by hydrogen. The specific changes in both phases of steel were observed. In the ferritic phase, strong increase of dislocation density was noticed. Longer time of hydrogen charging leaded also to the strips and twin plates formation in ferrite phase. In the austenitic phase, the generation of stacking faults, followed by the formation of α' martensite was remarked. KW - Steel KW - Hydrogen KW - Embrittlement KW - Electron backscatter diffraction KW - SEM PY - 2006 DO - https://doi.org/10.4028/www.scientific.net/SSP.112.133 SN - 1662-9779 VL - 112 SP - 133 EP - 140 AN - OPUS4-38031 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nolze, Gert T1 - Interphase boundary characterization in duplex steel and iron meteorites using EBSD technique JF - Archives of Metallurgy and Materials N2 - The properties of materials are mainly described by the orientation distribution of the crystalline phases in a material. Beside the so considered anisotropy also the grain as well as phase boundaries are of extreme importance for a whole string of properties, e.g. the strength of a material. On the example of the interface between fcc and bcc iron the discovered and derived models are discussed. Although the common models are based on the crystal lattice description, the atomic configuration on the interface is analysed. Since experimentally a wide spread of orientations data appears the consideration of the frequency distribution is proposed to find at least the main orientation relationship between fcc and bcc. High-indexed pole figures as well as the Euler subspace are introduced in order to increase the accuracy and to compare different measurements. For the sake of simplicity EBSD measurements on iron meteorites are used since they commonly consist of large fcc single crystals which transformed to a low and very specific number of bcc grains. In special cases the described procedure could also be used for steels. KW - Orientation relationships KW - Electron backscatter diffraction KW - Steel KW - Iron meteorites KW - Kurdjumov-Sachs KW - Nishiyama-Wassermann PY - 2006 SN - 1733-3490 SN - 0004-0770 SN - 0860-7052 VL - 51 IS - 1 SP - 15 EP - 22 AN - OPUS4-38030 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. I. A1 - Nolze, Gert T1 - Investigation of the competitive grain growth during solidification of single crystals of nickel-based superalloys JF - Crystallography Reports N2 - The competitive growth of columnar grains in a single-grain selector, which is used for directional solidification of single-crystal blades from nickel-based superalloys, has been investigated by electron backscattered diffraction and local X-ray diffraction analysis. It has been found that the competitive grain growth in a starter block is determined by the crystallographic factor: rapidly growing grains with the axial orientation close to the [001] direction dominate in this part of the casting. For the competitive grain growth in a helicoidal separator, the geometric factor (the position of a grain at the input of the separator) is also important. The results obtained suggest that an appropriate geometry of the single-grain selector was chosen. In addition, the distribution of the orientations of columnar grains obtained by electron backscattered diffraction, can be used for approximate estimation of the yield of suitable (i.e., with the deviation of the axial orientation from the [001] direction within a specified tolerance) single-crystal blades. KW - Electron backscatter diffraction KW - Single crystal KW - Growth competition KW - Nickel alloy PY - 2006 DO - https://doi.org/10.1134/S1063774506040298 SN - 1063-7745 SN - 1562-689X VL - 51 IS - 4 SP - 710 EP - 714 AN - OPUS4-38028 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -