Abstract

NAJARRO-QUINTERO, Rodolfo et al. Using ladle furnace slag and rice straw ash as components of a flux for weld overlay. Min. Geol. [online]. 2018, vol.34, n.3, pp. 334-347. ISSN 1993-8012.

The work addresses the use of rice straw ash and white slag from steel refining as components of an agglomerated flux, for weld overlay by Submerged Arc Welding. Its location in the CaO-SiO₂-MgO state diagram as well as the addition of SiO₂ required to cause a displacement towards a region of better properties of the flux matrix was defined from the average composition of the slags. The increasing of SiO2 was made by the addition of ash from the combustion of rice straw. A Cr-Mn-C alloy system was incorporated into the flux matrix. Two fluxes were elaborated, one with 20% sodium silicate and the other one with 30%. The fluxes were characterized in terms of morphometric characteristics and resistance of the grains, and properties of the deposits (microstructure, geometry, and chemical composition). It was concluded that white slag from steel works, with addition of rice straw ash, are suitable for shaping the matrix of an overlay flux, and that the addition of 30% of silicate allows greater grain strength, less dilution and a greater transfer of alloying elements to the tank. The microstructure, represented by the high presence of martensite and residual austenite, is suitable for covering pieces exposed to abrasive wear.

Keywords : steel slag; recycling; weld overlay; flux.

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