The Research On Air Furnace Brazing Technology In Oxygen Lance Nozzle

The oxygen lance nozzle is the very important oxygen tool in convertersteelmaking, it works about1400mm far from the melten steel,in normallyconverting, the oxygen blows from the nozzle at the rate of about2Maches to thesueface of the liquid steel, and the bottom of the nozzle will withstand the hightemperature radiation that higher than2000℃. The oxygen lance nozzle will stretchinto the slag and blow nitrogen after pouring the steel, which will protect the furnacethrough splashing. So the main forms of the lose efficacy of the oxygen lance aremelting, erosion, corrosion deformation and leakage, especially cool it in the highwater pressure, which will never allow leakage, cracking when it works, high securityis required. Therefore, correctly selecte the material of the oxygen lance nozzle andforming technology, reasonablely choose the brazing methods, scientificly use thebrazing fillers, develop the suitable modified brazing flux, and make the process anddetermine the process parameters are important to the success of brazing, also arevital practical significance to improve the level of smelting.On the comprehensive consideration, we braze the oxygen lance nozzle in airfurnace.In the selection of the brazing fillers, we choose silver filler metals(BAg45CuZn) and (BAg50CuZnCd). In the use of the brazing flux, through theanalysis and experiment, we designed and made up creamy silver flux that is suited tothe air furnace brazing on the basis of the domestic silver flux,we call it modifiedbrazing flux. We test the melting points、wetting and chemical compositions of themodified brazing fluxs,then analyse the microstructure of brazing seams through theoptical microscopy microscope, X-ray diffraction and electron microscope.The resultsof the study show that the modified brazing fluxs have common features that are easyto preserve and have good hydrolysis reusability, furthermore, they have moreexcellent performance such as easy to hang, low melting points, good air-tightness,wetting and spread the good performance. The texture of the brazing seam arecompact and the mechanical properties of the joint are assured with the help of themodified brazing fluxs.In the selection of technological parameters, the experimental results show that:when braze in the air furance with the brazing filler metal BAg45CuZn, it is moreideal if we take the isothermal measures below the melting point, keep the heatingtemperature at820℃, the holding time at10min and0.1mm clearance, then cool itin air furnace. Furthermore, wall thickness also has certain effect on the organizationand property of the weld joint: when the heating temperature is constant, the holdingtime is in proportional to the square of the wall thickness; when the wall thickness is constant, the holding time is in contrast with the heating temperature.Choose the more reasonable technological parameters to braze the oxygen lancenozzles with the modified brazing fluxs, then test them. The results show that: thesebrazing seams are compact, the metallurgical effect are good; and the First Test Yieldhas reached nearly90%, the average service life of the products is513furnaces,which is close to538furances compared with the oxygen lance imported fromGermany.