Design and Development of Submerged Arc Welding Acidic Flux

An acidic flux was intended and developed with the variation of some flux constituents. The basicity index of the flux was kept as 1.84. It was designed to weld the mild steel plates on submerged arc welding machine. A study was done with developed flux on two-level factorial design. Voltage and current were the controlled parameters along with feed rate, nozzle distance and creep feed as uncontrolled parameters selected for experimentation. Eight experiments were performed. Weld bead width and Hardness were the responses measured. Design expert software was used the do the analysis. Finally, it can be determined that travel speed was the most momentous factor for the hardness and weld bead dimensions of the joint.

INFLUENCE OF THE BASICITY INDEX ON WELDING ELECTRODE COATINGS ON THEIR WELDING AND TECHNOLOGICAL PROPERTIES

At this article presented the results of researches on studying of influence of basicity index BI of the electrode coating and the Melting Temperature Tm of the slag of electrode coatings consisting of a two-component CaO-SiO2 oxide system and ore-mineral raw materials of the Republic of Uzbekistan on the welding and technological properties of the welding electrodes. The relationship between these indicators was determined, the strength of linear correlation of which was estimated using the coefficient of determination R2. The influence of the BI value on such properties of the welding electrode as the breaking length of the arc, the formation of the deposited metal, and the formation of a visor or cover at the end of the electrode is established. Based on the research results, recommendations for the basicity index BI of the electrode coating were identified, which can be used in the development of electrode coating compositions for their effective impact on the welding and technological properties of welding electrodes.

Investigation of the chemical composition of ash dense fractions of low-alumina coal to substantiate the choice of charge components for coking

The scientific article is devoted to the study of the structural content of coal fractions, which differ in density. The main attention is paid to the study of the chemical composition of ash dense fractions of weakly burned coal. This will extend the idea of coal ash. The publication presents a qualitative and quantitative analysis of the chemical composition of low-alumina coal, which was used to calculate the ash index of the main samples, which in turn allowed us to calculate a preliminary estimate of coke on the CRI reactivity and coke strength after the CSR reaction. From the presented results it turns out that the fraction with a density <1.25 g/cm3 and> 1.3 g/cm3 have the worst technological characteristics. Keywords: density fractions, basicity index, coal, ash, chemical composition, acidic oxides, reactivity.

Effect of basicity on cementitious activity of modified electric arc furnace steel slag

Electric arc furnace steel slag was modified by wastes in hot-stage process with the aim to improve the cementitious activity. Effect of basicity on cementitious activity of modified steel slag was investigated in this research. The modified slag was characterized by XRD, DTA and Raman spectra techniques to investigate the correlations between structural features and the cementitious activity. The results showed that modified steel slag with a basicity index of 1.67 possessed the highest activity index, 107%, due to the precipitation of Belite, high content of amorphous phase and low polymerization degree. The polymerization degree of modified slag was demonstrated by nonbridging oxygen per tetrahedrally coordinated cations value which was calculated through curve-fitted Raman spectra. The value of modified slag increased as the basicity promoted from 1.05 to 1.67, indicating a lower degree of polymerization. Modified slag with a basicity index of 1.86 possessed the poor cementitious activity mainly because of the significant decrease of glass phase content.

Effect of Flux Constituents and Basicity Index on Mechanical Properties and Microstructural Evolution of Submerged Arc Welded High Strength Low Alloy Steel

The application of high strength low alloy (HSLA) steels has been limited by unavailability of suitable joining and filler metals in submerged arc welding (SAW) processes. The present work aims at the design and development of flux for Submerged Arc Welding of HSLA steel. In the work L8 array of Taguchi Design is used to formulate eight types of fluxes to vary basicity index (BI) from 1.26 to 2.81 and to study the effect of flux constituents and basicity index on tensile strength, microhardness and microstructure of the weld metal. Empirical models for ultimate tensile strength and microhardness at the centre of weld versus flux constituents and basicity index have been developed. From the experiments it is found that ultimate tensile strength increase with increase of basicity index with minimum at 1.26 increases upto 2.33 and then further decreases whereas opposite in case of microhardness which is highest at 1.26 and minimum at 1.9. Increase of CaO in the flux increases ultimate tensile strength but microhardness remains unaffected whereas increase of SiO2 decreases ultimate tensile strength but microhardness remains constant. Microhardness decreases critically with increase of CaF2.

Melting Characteristics of the Stainless Steel Generated From the Uranium Conversion Plant

The partition ratio of cerium (Ce) and uranium (U) in the ingot, slag and dust phases has been investigated for the effect of the slag type, slag concentration and basicity in an electric arc melting process. An electric arc furnace (EAF) was used to melt the stainless steel wastes, simulated by uranium oxide and the real wastes from the uranium conversion plant in Korea Atomic Energy Research Institute (KAERI). The composition of the slag former used to capture the contaminants such as uranium, cerium, and cesium during the melt decontamination process generally consisted of silica (SiO2), calcium oxide (CaO) and aluminum oxide (Al2O3). Also, Calcium fluoride (CaF2), nickel oxide (NiO), and ferric oxide (Fe2O3) were added to provide an increase in the slag fluidity and oxidative potential. Cerium was used as a surrogate for the uranium because the thermochemical and physical properties of cerium are very similar to those of uranium. Cerium was removed from the ingot phase to slag phase by up to 99% in this study. The absorption ratio of cerium was increased with an increase of the amount of the slag former. And the maximum removal of cerium occurred when the basicity index of the slag former was 0.82. The natural uranium (UO2) was partitioned from the ingot phase to the slag phase by up to 95%. The absorption of the natural uranium was considerably dependent on the basicity index of the slag former and the composition of the slag former. The optimum condition for the removal of the uranium was about 1.5 for the basicity index and 15wt% of the slag former. According to the increase of the amount of slag former, the absorption of uranium oxide in the slag phase was linearly increased due to an increase of its capacity to capture uranium oxide within the slag phase. Through experiments with various slag formers, we verified that the slag formers containing calcium fluoride (CaF2) and a high amount of silica were more effective for a melt decontamination of stainless steel wastes contaminated with uranium. During the melting tests with stainless steel wastes from the uranium conversion plant (UCP) in KAERI, we found that the results of the uranium decontamination were very similar to those of the uranium oxide from the melting of stimulated metal wastes.