Structure and Properties of Coatings Made with Self Shielded Cored Wire

Abstract

The welding technologies are widely used for design of protection layer against wear and corrosion. Hardfacing, which is destined for obtaining coatings with high hardness, takes special place in these technologies. One of the most effective way of hardfacing is using self shielded flux cored arc welding (FCAW-S). Chemical composition obtained in flux cored wire is much more rich in comparison to this obtained in solid wire. The filling in flux cored wires can be enriched for example with the mixture of hard particles or phases with specified ratio, which is not possible for solid wires. This is the reason why flux cored wires give various possibilities of application of this kind of filler material for improving surface in mining industry, processing of minerals, energetic etc. In the present paper the high chromium and niobium flux cored wire was used for hardfacing process with similar heat input. The work presents studies of microstructures of obtained coatings and hardness and geometric properties of them. The structural studies were made with using optical microscopy and X-ray diffraction that allowed for identification of carbides and other phases obtained in the structures of deposited materials. Investigated samples exhibit differences in coating structures made with the same heat input 4,08 kJ/mm. There are differences in size, shape and distribution of primary and eutectic carbides in structure. These differences cause significant changes in hardness of investigated coatings.

Structure Investigation of Titanium Metallization Coating Deposited onto AlN Ceramics Substrate by Means of Friction Surfacing Process

“…Figure 3b shows the SEM image of the coating from the surface view at its boundary with the substrate. In all types of coatings, the coverage boundary zone is a sensitive area with a high risk of delamination, which was investigated by [33][34][35][36][37]. It is due to the relatively high level of internal stresses resulting, for example, from the technological conditions of coating application and extremely different physical properties of ceramics and metals, such as the thermal expansion coefficient and thermal conductivity coefficient [38][39][40][41].…”

Review on hardfacing as method of improving the service life of critical components subjected to wear in service

“…Dilution increases with increasing welding current and increased presence of chromium in a chromium carbide paste hardfacing; these result in decreasing hardness; however, lower welding current increased hardness and wear rate of the hardfacing [18,19]. Gucwa et al [38] noted that differences in the sizes, shape and distribution of primary and eutectic carbides cause significant changes in the hardness of hardfacings. A hardfacing alloy with chromium (33%) and carbon (4.5%) used to hardface an excavator bucket teeth by manual metal arc welding (MMAW) technique showed better wear resistance than the unhardfaced teeth [39].…”

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“…Moreover, it allows to obtain surface layers of greater thickness compared to other methods of coatings formation. One of the most common among many hardfacing methods to increase wear resistance is the use of hardfacing with a self-shiealded fluxcored wire (FCAW-S) [71][72][73][74]. FCAW-S are characterized by simplicity of welding equipment, high hardfacing productivity, ability to achieve a high degree of alloying of the weld metal, the arc visibility [74].…”