State of the Art in the Control of Inclusions in Tire Cord Steels - a Review

Abstract

The control of inclusions in tire cord steels and techniques used in the production process are extensively reviewed. Inclusion and segregation requirements for the tire cord steel are discussed. The deformability of an inclusion is significantly affected by its AI203 content. Inclusions containing 20% AI20 3 has best deformability. The undeformable inclusions can be avoided by controlling the dissolved aluminum in the steel. Low basicity slags favour the generation of deformable inclusions. When the basicity R (=CaO/Si0 2 ) = 0.8-1.5, the dissolved aluminum in the steel should be 1-5ppm to achieve 20% AI 203 in inclusions. With R=1.0-1.4, in order to control [AI] in the range of 1-5ppm, the slag should contain approximately 8% A120 3. The technologies to control inclusions in tire cord steels are reviewed including steel deoxidizer choice, steel refining method, slag carry over from BOF to the ladle, ladle stirring practice, control of nitrogen pickup and caster curvature. Control methods to decrease the central segregation in the tire cord steel are briefly reviewed, such as electromagnetic stirring during continuous casting.The work presents theoretical fundamentals of the process of refining molten steel from liquid non-metallic inclusions, using the method of filtration with ceramic filters -the thermodynamic precondition for the absorption of liquid non-metallic inclusions on the surface of a ceramic filter. The theoretical consideration has been supported by the results of laboratory tests on the filtration of steel which was previously reduced with complex deoxidants giving liquid products of deoxidization. The filtration process of steel melts reduced with complex deoxidants of type AI-Mn-Si has proved to be more efficient. The deoxidation products were identified on the filtration surface of the ceramic filters.

Thermodynamic Model for Prediction of Slag-Steel-Inclusion Reactions of 304 Stainless Steels

“…49) In order to avoid the generation of the nondeformable Al 2 O 3 -MgO-rich inclusions, the Si-Mn deoxidation was introduced. However, the aluminum in the added ferrosilicon alloy can significantly promote the formation of spinel inclusions in Si-Mn-killed stainless steels.…”

Modeling on Fluid Flow and Inclusion Motion in Centrifugal Continuous Casting Strands

“…The trajectories of inclusions were calculated using Lagrangian approach which treats inclusion particles as a discrete phase [42] , by considering the force balance acting on them [43] .…”

“…As shown in Fig.7, entrained bubbles can float upward and escape from the top of the mold. In actual practice, bubbles beneath the top surface of the molten steel are likely to be entrapped by the solidifying shell, eventually leading to defects such as surface slivers, blisters or internal defects in the rolled product [43] . Hence, to evaluate gas entrainment, the gas volume below the top surface, calculated by Eq.…”

Application of Alkali Oxides in LF Refining Slag for Enhancing Inclusion Removal in C96V Saw Wire Steel

“…1,2) In addition, some small inclusions would cause wire broken because they are too hard to deform. 3) According to the exist research results the main kinds of inclusions in tire cord steel or saw wire steel are MnO-SiO 2 -Al 2 O 3 and CaO-SiO 2 -Al 2 O 3 system, it has excellent deformability when its compositions are located in the low melting zone. For instance, there are three aspects to control inclusions in cord wire steel and saw wire steel: (i) Excellent deformability, inclusions can deform or break into smaller size easily, which means, the number of inclusion which composition concentrate in low melting zone should be as much as possible; (ii) The total number of inclusions should be as less as possible; (iii) Removed large and hard inclusions should be as much as possible.…”