METALLOGRAPHIC INVESTIGATIONS OF QUALITY OF WELDING SEAM OBTAINED BY SILICOMANGANESE SLAG FLUX WELDING

Results of the study of metallurgical wastes application as components of welding fluxes are given. Composition and production technology of a new welding flux using silicomanganese slag as a component have been developed. Results of this slag application in manufacture of welding fluxes are presented. In order to study quality of welded seams, metallographic analysis was carried out and the grain size and level of nonmetallic inclusions contamination were determined. Metallographic studies were made with the help of OLYMPUS GX-51 optical microscope in magnification range of 100  –  1000  times. Influence of fractional composition of fluxes on their welding technological properties was studied. Optimal fraction was selected, ensuring low level of contamination of metal of welding seam with non-metallic oxide inclusions, in particular non-deformable silicates and oxides. It has been established that application of welding flux fine fraction in an amount of 30  –  40  % ensures reduction in degree of welding seam metal contamination with non-metallic inclusions. The metallographic analysis of welding seam metal shows that introduction of fine fraction does not affect its structural components. Welding seam metal has a ferrite-pearlite structure; ferrite is presented in form of non-uniform grains elongated in the direction of heat extraction. It was determined that the optimum content of a fraction less than 0.45  mm in the flux is 30  –  40  %. To raise technical and economic indicators, it is suggested to mix fine fraction with liquid glass. Application of ceramic flux made of silicomanganese slag dust of 0.45  mm fraction, bonded by liquid glass, provides reduction in the welding seam metal level of contamination with nonmetallic inclusions. At the same time, increase in its volume from 15 to 40  % does not significantly affect the level of welding seam metal contamination with nonmetallic inclusions and its microstructure. Microstructure of welding seam metal is represented by perlite and ferrite. It was found that fine fraction introduction with use of liquid glass in an amount of 15  –  20  % is optimal in production of ceramic flux.

welding, flux, metal, silicomanganese slag, fraction, chemical composition, microstructure, grain size, nonmetallic inclusions

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