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Stockholm, Sweden

Tidblad J.,Swerea Kimab Ab
Atmospheric Environment | Year: 2012

Climatic parameters and pollution data from the 6FP NOAHs ARK project 'Global Climate Change Impact on Built Heritage and Cultural Landscapes' together with chloride deposition data have been used to predict atmospheric corrosion of metals in 2010-2039 and 2070-2099. Maps of carbon steel and zinc show that future atmospheric corrosion of metals in Europe are dominated by the effects of chloride deposition in coastal and near-coastal areas. The change can in extreme cases be as high as one corrosivity category and in coastal areas of southern Europe corrosion can be higher than the highest values experienced today in Europe. © 2012 Elsevier Ltd. Source


Persson D.,Swerea Kimab Ab | Thierry D.,French Corrosion Institute | LeBozec N.,French Corrosion Institute | Prosek T.,French Corrosion Institute
Corrosion Science | Year: 2013

NaCl induced atmospheric corrosion of ZnAl2Mg2 coated, electrogalvanised (EG) and hot dipped galvanised (HDG) steel was studied using in situ infrared reflection absorption spectroscopy, XRD and SEM. Initial corrosion leads to the formation of Mg/Al and Zn/Al layered double hydroxides (LDHs) on ZnAl2Mg2, due to the anodic dissolution of Zn-MgZn2 phases and cathodic oxygen reduction on Zn-Al-MgZn2, Al-phases and on zinc dendrites. In contrast to EG and HDG, were no ZnO and Zn5(OH)8Cl2{dot operator}H2O detected. This is explained by the buffering effect of Mg and Al which inhibit the ZnO formation, reduce the cathodic reaction and corrosion rate on ZnAl2Mg2. © 2013 Elsevier Ltd. Source


Hutchinson B.,Swerea Kimab Ab | Jain J.,Deakin University | Barnett M.R.,Deakin University
Acta Materialia | Year: 2012

Plastic deformation processes in hexagonal metals are complex and are best analyzed using procedures such as visco-plastic self-consistent crystal plasticity modelling. These involve a large number of adjustable parameters and make limited use of independent input data. Using physical arguments, the authors show that several of the parameters can be replaced by experimentally measured values of critical resolved shear stresses from the literature. A further simplification derives from the argument that all deformation modes interact with the same substructure, and so a common work-hardening behaviour can be assumed as a reasonable first approximation. Furthermore, many microstructural contributions to the strength can be introduced through a single constant term. In these ways, the twelve or more adjustable parameters in the model are reduced to only three. This new approach is tested critically by applying it to a sheet magnesium alloy for which the plastic strain ratio varies markedly during the test. Its complex plastic behaviour, which arises from changes among the active deformation modes, is successfully predicted. A benefit of the present approach is that the effect of metallurgical variables such as grain size or precipitation strengthening can be readily investigated. Although tested here for a magnesium alloy, the same principles should be applicable to other hexagonal close-packed materials. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Source


M'Saoubi R.,Seco Tools AB | Chandrasekaran H.,Swerea Kimab Ab
International Journal of Advanced Manufacturing Technology | Year: 2011

Cutting tool temperature distribution was mapped using the IR-CCD technique during machining of carbon steel AISI 3115 and stainless steel AISI 316L under orthogonal cutting conditions using flat-face geometry inserts. The effect of work material treatment on tool temperature was investigated, and the results showed that AISI 3115 in heat-treated state displayed higher tool temperature than the as-rolled state. Stainless steel 316L with high sulphur content (0.027 wt.%) and calcium treatment displayed lower cutting tool temperature than the variant with low sulphur (0.009 wt.%). The experimental results were compared with theoretical tool temperature distributions based on a modified version of Komanduri and Hou's analytical model. In particular, variable frictional heat source and secondary shear were introduced and modelling of the tool stress distribution on rake surface was also considered. © 2011 Springer-Verlag London Limited. Source


Tolf E.,Scania AB | Hedegard J.,Swerea Kimab Ab | Melander A.,KTH Royal Institute of Technology
Science and Technology of Welding and Joining | Year: 2012

In normal production of resistance spot welded galvanised structures, it is difficult to completely avoid surface breaking cracks. Known key factors to cause cracking are zinc coating, electrode wear during subsequent welding and insufficient electrode cooling. In this report, an embrittlement mechanism was investigated that could be coupled to the galvanisation method for dual phase steels. With identical bulk material and weld parameters, the first 50 spot welds were crack free with electrogalvanised coating, while only 10 out of 50 were crack free with hot dip galvanised coating. Energy dispersive X-ray spectroscopy analysis of the worn electrode surfaces used for welding of the hot dip galvanised coating revealed areas of aluminium oxide. Since aluminium oxide is a very strong isolator, the electrical resistance will increase, which in turn is suggested to increase the surface temperature of the spot weld and thereby increase the probability for liquid metal embrittlement and surface cracks. © 2013 Institute of Materials, Minerals and Mining. Source

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