Abstract
The aim of the experiment in this work is to modify the Al2O3 inclusions in high-carbon hard wire steel by magnesium treatment. The general evolution process of inclusions in steel is: Al2O3 → MgO·Al2O3(MA) → MgO. The unreacted core model was used to study the modification process of inclusions. The results show that the complete modification time (tf) of inclusions is significantly shortened by the increase of magnesium content in molten steel. For Al2O3 inclusions with radius of 1 μm and Mg content in the range of 0.0005–0.0055%, the modification time of Al2O3 inclusions to MA decreased from 755 s to 25 s, which was reduced by 730 s. For Al2O3 inclusions with a radius of 1.5 μm and Mg content in the range of 0.001–0.0035%, the Al2O3 inclusions were completely modified to MgO inclusions from 592 s to 55 s. The Mg content in the molten steel increased 3.4-fold, and the time for complete modification of inclusions was shortened by about 10-fold. With the increase of Al and O content in molten steel, the complete modification time increased slightly, but the change was small. At the same time, the larger the radius of the unmodified inclusion is, the longer the complete modification time is. The tf of Al2O3 inclusions with a radius of 1 μm when modified to MA is 191 s, and the tf of Al2O3 inclusions with a radius of 2 μm when modified to MA is 765 s. According to the boundary conditions and the parameters of the unreacted core model, the MgO content in inclusions with different radius is calculated. The experimental results are essentially consistent with the kinetic calculation results.
Highlights
Hard wire, known as hard wire rod, is usually known as high-carbon hard wire for high-quality carbon structural steel with a carbon content of not less than 0.6%
Magnesium has a strong affinity with oxygen and sulfur, which can effectively reduce the content of O and S in steel, and improve the quantity and morphology of inclusions in steel; it has an obvious modification effect on oxide inclusions and plays a role in purifying molten steel [9,10,11,12,13,14]
Since there are multiple dynamic steps involved in the model, a restrictive analysis is carried out to study the influence of each step on the modification time of inclusions
Summary
Known as hard wire rod, is usually known as high-carbon hard wire for high-quality carbon structural steel with a carbon content of not less than 0.6%. The alumina nonmetallic inclusions in hard wire steel have an important influence on the fatigue resistance of wire breaking or hard wire products during cold drawing, resulting in early fracture of steel in practical application [1,2,3]. The solubility of magnesium in molten steel is relatively high. Magnesium has a strong affinity with oxygen and sulfur, which can effectively reduce the content of O and S in steel, and improve the quantity and morphology of inclusions in steel; it has an obvious modification effect on oxide inclusions and plays a role in purifying molten steel [9,10,11,12,13,14]. Yang et al [19] added magnesium to
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