Precipitation and Solid Solution of Titanium Carbonitride Inclusions in Hypereutectoid Tire Cord Steel

摘要

The properties of titanium carbonitride Ti(Cx N1-x )inclusions precipitated during solidification of tire cord steels and the thermodynamic conditions for their decomposition and solid solution during billet heating were investigated using a thermodynamics method.The solid solution of Ti(Cx N1 -x )inclusions during high-temperature heating was also studied experimentally.The results revealed that:(1)the higher the content of carbon in the tire cord steel is, the greater the value of x in the Ti(Cx N1 -x )inclusions is;(2)the higher the content of carbon in the tire cord steel is,the earlier the Ti(Cx N1 -x )inclusions precipitated during the solidification process and the lower the solidification front temperature is during precipitation;(3)when an 82A steel sample was heated to 1 087 ℃,the Ti(Cx N1 -x )in-clusions possess the thermodynamic conditions of decomposition and solid solution;and (4)when 82A samples were heated to 1 1 50 and 1 250 ℃,the total number of Ti(Cx N1 -x )inclusions larger than 5 μm in diameter decreased by 55.0% and 70.3%,respectively.In addition,although smaller inclusions with diameter less than 2 μm continued to decompose when the sample was heated at 1 250 ℃ for 2 h and then cooled to 1 000 ℃ in the furnace,the number of inclusions larger than 5 μm in diameter increased.