含微量钛低合金结构钢的热轧工艺优化

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

利用热模拟试验机和透射电镜研究了含微量钛低合金结构钢在轧制过程中TiC的析出规律,分析了轧制温度及轧后终冷温度对TiC析出的影响,并以TiC的充分析出为前提条件,优化了钢的轧制工艺,并对其性能进行了分析。结果表明:在奥氏体温区轧制时,随着轧制温度的降低,TiC的析出数量增多,且尺寸减小,850℃左右变形对TiC的析出最为有利;在铁素体温区的高温部(700℃),TiC的析出既有弥散析出又有相间析出,在低温区(600℃)则以弥散析出为主,在650℃时析出物数量多、尺寸小、分布弥散;优化后的轧制温度为830℃,终冷温度为650℃,在细晶强化的同时,还可获得最佳的TiC析出强化效果,使钢的屈服强度提高80MPa左右。

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 ℃.