Hot Rolling Process Optimization of Low Alloy Structure Steel Containing Little Titanium

Precipitation behavior of TiC during hot rolling in a low alloy structure steel containing little titanium was studied by means of thermal simulation and TEM analysis. The effects of rolling temperature and final cooling temperature on the precipitation of TiC were also investigated, meanwhile the process parameters of rolling were optimized for the precipitation of TiC as many as possible. And the properties of the test steel were analyzed. The results show that in austenite region with the decrease of rolling temperature, TiC precipitates increased in quantity but decreased in size, and about 850 ℃ was the best deformation temperature for precipitation of TiC. In the high temperature region during the ferrite transformation (700 ℃), both dispersive precipitates and inter-phase precipitates were observed, while in the low temperature region (600 ℃) dispersive precipitation was dominant. Large quantity of small size precipitates distributed dispersively at 650 ℃. Grain refinement hardening and an optimal hardening effect of TiC precipitation which resulted in a yield strength increment of 80 MPa can be obtained through the optimized rolling process with rolling temperature of 830 ℃ and finish cooling temperature of 650 ℃.