Characteristics and distribution of TiN inclusions in 20CrMnTi gear steel
LI Yao1, CHENG Guo-guang1, LU Jin-long1,2, SUN Jun3
1. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China; 2. Technology Center, Baowu Group Guangdong Shaoguang Iron and Steel Co., Ltd., Shaoguan 512123, Guangdong, China; 3. Technology Center, Xining Special Steel Co., Ltd., Xining 810005, Qinghai, China
Abstract：In order to study the precipitation and control of TiN inclusions in Ti-bearing gear steel, the distribution and morphology of TiN inclusions in two quenched specimens of 20CrMnTi gear steel were observed by means of scanning electron microscope, the size and quantity of TiN inclusions in samples were counted by the inclusion automatic analysis system, and a mathematical model was established to calculate the precipitation and growth process of TiN inclusions in experimental samples. The results showed that TiN inclusions precipitated earlier and the precipitation volume fraction was larger in the sample with higher Ti content during solidification, and as a result of more TiN inclusions precipitated out, the final size of precipitated TiN inclusions became smaller. When the quantitative density of TiN particles in samples increased from 37.28 to 58.65 mm-2, the average equivalent diameter decreased from 2.33 to 1.49 μm. By providing a sufficient number of oxide particles as the precipitation core of TiN inclusions during solidification, improving the rate of heterogeneous nucleation and significantly increasing the amount of TiN precipitation, the overall size of TiN precipitation can be reduced, which can provide a new idea for the control of TiN inclusions in Ti-bearing gear steel.
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2020, Vol. 30 
