The role of mould fluxes in continuous casting is reviewed. The main functions of the flux are described and the importance of the flux in providing lubrication and the right level of heat transfer between the shell and the mould is described. The major problems of longitudinal, transverse and star cracking, gas and slag entrapment and deep oscillation marks in the steel product and 'sticker breakouts' are analysed. The important physical properties of the flux in combating these various problems are identified. Physical property data for the fluxes are given.

This review critically evaluates the factors affecting the process of slag splashing. Two mechanisms are involved in slag splashing, namely 'slag wash coating' and 'slag ejection coating'. Our knowledge of slag splashing is largely based on physical modelling studies. It is necessary to optimise the following for good slag splashing:(ii) The characteristics of the nitrogen blow (Gas flow, Lance height, Lance angle, Slag depth); and (iii) Slag composition. It is important that the slag contains the right blend of low-melting and high-melting phases. The low-melting (FeO-rich) phases ensure good adhesion between the slag and refractory whereas the high-melting phases provide erosion resistance and a thermal barrier. Good slag properties are obtained with a FeO content of ca. 13 % and MgO should be supersaturated (Ͼ8 % MgO) to ensure that the slag is MgO-saturated rather than CaO-saturated so that high-melting MgO · Fe 2 O 3 is formed rather than the low-melting calcium ferrites.The factors affecting the uniformity of the slag-splashed layer are discussed.

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In structural fire engineering, the importance of bolt assemblies is often overlooked. Connection design uses the temperature-dependent bolt strength-reduction factors prescribed in Eurocode 3, despite the existence of two distinct failure modes under tension; necking of the bolt shank, and thread-stripping. While literature exists to predict failure modes at ambient temperature, there is no method for failure mode prediction for elevated temperatures where ductility is critical to avoid collapse. Galvanised M20 structural bolt assemblies and bolt material from a single batch have been tested under tension at a range of temperatures and strain-rates typical of those experienced in fire. Turned-down bolt test data produced stress-strain curves characteristic of different microstructures at ambient temperature, despite a tempered-martensitic microstructure being specified in the standards. The failure modes of bolt assemblies were found to be dependent on the as-received microstructure at ambient temperature. At elevated temperatures, however, only thread-stripping was observed.Keywords: Bolt assemblies, ductile and brittle failure, thread stripping, microstructure INTRODUCTIONThis paper examines the tensile behaviour of bolt material, in the form of turned-down bolts, and bolt assemblies, at a range of temperatures and strain-rates. A single batch of galvanised M20 structural bolting assemblies, in accordance with BS EN 15048 [1], were chosen, as they are commonly used in UK construction. The bolts were Grade 8.8, while the pairing nuts were of Property Class 10. The bolt assemblies were donated by a UK distributor; which had imported the components, carried out quality assurance testing and applied its own manufacturers mark. This is common practice in the UK, where all structural bolts are currently imported due to the high cost of raw materials [2]. According to ISO 898-1 "A distributor who distributes fasteners that are marked with his (or her) own identification mark shall be considered to be the manufacturer" [3], which makes the original overseas manufacturer untraceable.The strength reduction factors provided in Table D.1 of Eurocode 3 [4] came directly from the results of testing carried out during the 1990s on bolt assemblies manufactured in the UK [5,6]. At the time at which this research was carried out 'structural' bolting assemblies did not exist. All nuts and bolts could be purchased individually and interchangeably. Quality assurance testing, therefore, did not include the mechanical testing of the assembly as a whole. Geometrical differences also exist between the bolts tested by Kirby [5,6] and those discussed in this paper. Kirby tested assemblies of looser thread tolerance class combinations, known as 7H8g, as specified in BS 4190 [7]. However, the assemblies tested in this paper are of the tighter tolerance class 6AZ6g, as specified in . The equivalent tight tolerance class for uncoated assemblies is 6H6g, as specified in ISO 4017 [10] for fully-threaded bolts or ISO 4014 [11] for par...

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