Investigation of Ti inclusions in wire cord steel

Abstract

Ti content in specimens of 80 grade wire cord steel was measured by laser ablation inductively coupled plasma mass spectrometry. It was found that the average Ti content increased and then decreased during electrical arc furnace (EAF) tappingRrefiningRcontinuous casting. Under current control condition of 80 grade wire cord steel in Nanjing Iron and Steel United Co. Ltd (NISUCL), the calculation results in several aspects such as formation thermodynamics, solidification segregation and growth kinetics of TiN particles showed that the formation of TiN only took place in the two-phase region where the solidification ratio is greater than 98%, or in solid phase region; both solidification segregation of Ti and N increased with increasing cooling rate and the segregation tendency was greater with increasing solidification fraction. The greater the cooling rate during solidification, the smaller the size of precipitated TiN particles. The size of precipitated TiN particles is 3-7 mm, which accorded with the size measured in metallographic image of TiN inclusions found in wire rod specimens.

Understanding TiN Precipitation Behavior during Solidification of SWRH 92A Tire Cord Steel by Selected Thermodynamic Models

“…Cai et al [9] showed that the precipitation of TiN could only occur in the solid-liquid two-phase region where the solid fraction was greater than 0.95, and the particle size of TiN decreased with increasing cooling rate. Similar results were also reported in other references [11][12][13]. However, Liu et al [14] demonstrated that TiN would not precipitate in the liquid phase or mushy zone, but in austenite (γ-Fe).…”

“…where a TiN , a [Ti] , and a [N] denote the activities of TiN, Ti, and N in molten steel, respectively, herein, a TiN = 1; w [Ti] and w [N] denote the mass fractions of Ti and N in molten steel, respectively; f [Ti] and f [N] denote the activity coefficients of Ti and N, which can be estimated by Equations (10) and (11) [13], respectively.…”

“…Many researchers [2][3][4][9][10][11][12][13][14] have reported the precipitation behaviors of TiN inclusion in different types of steels over the decades. Jiang et al [4] found that the solidification segregation ratio of Ti was far greater than that of N, and reported that TiN inclusion would not precipitate until the solid fraction reached 0.9 when using SWRH 82A tire cord steel.…”

Formation of Inclusions in Ti-Stabilized 17Cr Austenitic Stainless Steel

“…The relationships for the activity coefficients of Ti and N (f Ti and f N , respectively) as a function of temperature are given by Eqs. [9] and [10]: [34][35][36] lg f i 1873 K 1600 C are obtained. Substituting these values into Eqs.…”

Effect of Ti Content on the Characteristics of Inclusions in Al–Ti–Ca Complex Deoxidized Steel

“…Titanium is always used as a kind of stabilizing element, which reacts with the carbon or nitrogen to form carbonitride to bind the soluble carbon and nitrogen, especially for IF steels, 1) Ti-bearing stainless steels 2) or wire cord steels. 3) In addition, Ti-oxide in steel can be nucleating sites for intragranular acicular ferrite during solidification, and improve mechanical properties around welded region in steels. [4][5][6][7][8] However, Ti-containing inclusions may also cause severe nozzle clogging problems, which are detrimental to steel production process.…”