Papers by Keyword: Segregation

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Authors: Christian Klinkenberg, C. Bilgen, T. Boecher, J. Schlüter
Abstract: Industrial thin slab casting and direct rolling processing started in 1989 with the world’s first CSP® plant at Crawfordsville (USA). Since this time CSP® and competing thin slab casting and direct rolling concepts have been developed to a standard process for hot strip production. Typical features of the CSP® process are the homogeneous structural and mechanical properties all along the strip. Direct hot rolling of thin slabs may be followed by a well defined cooling pattern to produce fine-grained HSLA steel or multiphase hot strip on the runout table. The product range covers low carbon as well as medium and high carbon steel grades comprising IF-, HSLA-, API-, electrical- and multiphase steel grades. CSP® processed thin hot strip is used for non-exposed parts and may substitute cold rolled strip. Hot strip from thin slab can be easily further processed to cold rolled and/or surface treated strip. Today process and material developments e.g. go for energy saving, rise in productivity, advanced surface requirements, HSLA and multiphase steel grades combining higher strength and ductility as well as multiphase steel grades for hot dip galvanizing.
Authors: Oras A. Al-Ani, J.P. Goss, N.E.B. Cowern, Patrick R. Briddon, Meaad Al-Hadidi, Raied Al-Hamadany, M.J. Rayson
Abstract: Removal of the dilaterous effects of iron in silicon is critical for the performance of multicrystalline silicon (mc-Si) solar cells, with internal gettering at extended defects including stacking faults and grain boundaries being one possibility. We present the results of a density function study of the behavoiur of iron at the intrinsic stacking fault and (001)–Σ 5 twist grain boundary, which both represent examples of fully bonded systems. Our results show iron is bound more strongly to the grain-boundary than the stacking fault, which we ascribe to a combination of Si-Fe chemistry and strain relaxation. However, we find that the binding energy of a single Fe atom to these extended defects is modest, and less than 0.5 eV.
Authors: B. Chen, Peter E.J. Flewitt, David John Smith, C.M. Younes
Abstract: A preliminary sensitivity examination of the ductility exhaustion based creep damage prediction model, currently used in the R5 high temperature assessment procedure, showed that material property inputs had significant effects on damage prediction. In the present work, the link between the microstructural factors and the susceptibility to inter-granular high temperature creep failure is considered. The latter was judged to be associated with the low creep ductility. Here, the longitudinal section of a creep specimen and the fracture surface were examined. Auger electron spectroscopy was used to investigate the grain boundary composition in this specimen, which failed after a creep test of 1038h at 550°C under a triaxial stress state. The present results demonstrate that there is a possibility to correlate the susceptibility to high temperature inter-granular fracture from the low temperature fracture investigations. Finally, the susceptibility of the pre-treated 316H stainless steel to inter-granular high temperature failure and the contribution to the creep damage model are briefly discussed.
Authors: René Le Gall, Guy Saindrenan, D. Roptin
Authors: Yuan Shan Li, Xu Chen, Yu Feng Luo
Abstract: In this paper, a new kind of Sn-Bi lead-free solder was fabricated via rapid solidification method by adding a series of microelements which can optimize the properties of Sn-Bi solder. When the solder was manufactured by Single Roller Melt Spinning Process, the faster the cooling rate is, the better the effect of restraining Bi segregation is. When the melt spinning rate was up to 1000 rpm, it had the best result. The effects of microelements on the melting characteristics, microstructure and properties of the new solder were also systemically studied. The results show that when the added content of Ag is 0.7%, Cu 0.3%, Ge 0.1%, In 0.5% and Sb 0.5%, the microstructure of the solder is fine, the extent of Bi segregation obviously decreases and the mechanical property is similar to that of Sn-37Pb solder. The melting point of the new solder is close to that of the Sn-37Pb solder. The mechanical and soldering properties are also similar to that of it.
Authors: Yi Kun Luan, Nan Nan Song, Yun Long Bai, Xiu Hong Kang, Dian Zhong Li
Abstract: A novel segregative carbide was discovered during the manufacture of high speed steel roll. The carbide with rectangular shape is a type of MC carbide not yet reported in the open literature. It is a face centered cubic carbide with a lattice parameter a=0.414445 nm, very close to the VC carbide but with a different chemical composition. The M represents the metallic elements (at.%): 91.80 V, 3.17 Cr, 2.19 Fe and 2.83 Mo.
Authors: Seong Gyoon Kim, Won Tae Kim, Yong Bum Park
Abstract: Abnormal grain growth (AGG) proceeds in case that normal grain growth is inhibited. It has long been known that the inhibition involves finely dispersed particles and/or the development of specific textures. There is another strong obstacle against the grain boundary (GB) motion; the solute atoms can reduce their energy by moving from the bulk into a GB. Resultant interaction between the solute atoms and a GB makes the GB motion more difficult. However the role of the GB segregation effect on AGG has not been clarified. In this study we simulate the 2D and 3D grain growth accompanying boundary segregation of solute atoms by using a phase-field model. It is shown that the segregation plays an important role on the occurrence of AGG. The boundary-segregation-induced AGG can take place when the average driving force of grain growth approaches a critical condition for pinning-depinning transition in solute-drag atmosphere.
Authors: Frédéric Christien, René Le Gall, Guy Saindrenan
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