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) tapping→refining→continuous 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 μm, which accorded with the size measured in metallographic image of TiN inclusions found in wire rod specimens.

Keywords:

• Wire cord steel
• Ti inclusion
• Thermodynamics
• Kinetics

This work was supported by the Hubei Province Key Laboratory of Systems Science in Metallurgical Process (Wuhan University of Science and Technology) (Grant No. C201017)