Optimization of Slag Chemistry Toward Inclusion Control for 28CrMo47 Drill Pipe Steel Based on Viscosity and Equilibration Studies
2015 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344XArticle in journal (Refereed) Published
During the refining of 28CrMo47 drill pipe steel, it is found that the product often has internal defects and cracks. The present work is initiated with a view to examine if these problems could be solved by optimizing the slag chemistry of the refining slag. Three series of slags, namely, slag A (57.09%CaO-15.74%SiO<inf>2</inf>-16.35%Al<inf>2</inf>O<inf>3</inf>-5.35%MgO, original slag in the steel plant), slag B (55%CaO-21%SiO<inf>2</inf>-12%Al<inf>2</inf>O<inf>3</inf>-7%MgO-5%CaF<inf>2</inf>), and slag C (51%CaO-17%SiO<inf>2</inf>-25%Al<inf>2</inf>O<inf>3</inf>-7%MgO) are designed and their viscosities are measured. The effect of Al<inf>2</inf>O<inf>3</inf> content on viscosity of the slag C is also investigated as part of the slag optimization. Slag-steel equilibrium experiments are subsequently carried out in order to understand the effect of the slag chemistry, especially the variation in the Al<inf>2</inf>O<inf>3</inf> content in the same on the inclusions in drill pipe steel. It is concluded that both increasing Al<inf>2</inf>O<inf>3</inf> content of the slag used in the refining unit in the plant and addition of CaF<inf>2</inf> could decrease effectively the slag viscosity. Inclusions in steel equilibrated with slag C1, corresponding to 51%CaO-7%MgO-25%Al<inf>2</inf>O<inf>3</inf>-17SiO<inf>2</inf>, consisted mainly of low melting point CaO-Al<inf>2</inf>O<inf>3</inf> complex, which did not have any negative effect on the steel quality.
Place, publisher, year, edition, pages
John Wiley & Sons, 2015.
Drill pipe steel, Inclusions control, Refining slag optimization, Slag-steel equilibration, Viscosity, Aluminum, Cracks, Drill pipe, Drills, Magnesia, Refining, Steel pipe, Steelmaking, Inclusion control, Inclusions in steels, Internal defects, Low melting point, Refining slag, Refining units, Slag chemistry, Slag viscosity, Slags
IdentifiersURN: urn:nbn:se:kth:diva-176194DOI: 10.1002/srin.201500217ScopusID: 2-s2.0-84941585679OAI: oai:DiVA.org:kth-176194DiVA: diva2:873971
QC 201511252015-11-252015-11-022015-11-25Bibliographically approved