Effect of annealing on dendritic segregation and elemental diffusion of gear steel billet
ZHAO Yi-na1， CHEN Yin-li2， YU Wei1， WANG Yun-long2， FAN Wen-sheng2
（1. Engineering Technology Institute， University of Science and Technology Beijing， Beijing 100083， China； 2. 2011 Collaborative Innovation Center for Common Steel Technologies， University of Science and Technology Beijing， Beijing 100083， China）
Abstract：In order to study the effects of annealing process on the dendritic morphology of 20CrMnTi gear steel slab，the distribution of alloying elements （C，Si，Cr and Mn） and its diffusion，the optical microscope （OM） was used to shape the dendrites before and after annealing. The appearance was compared and the distribution of the elements was quantitatively analyzed using an electron probe （EPMA），and the simulation was performed using the Dictra module in the Thermo-Calc software. The results showed that the dendritic morphology of the 20CrMnTi gear steel slab was more complete and clear，and the secondary dendrite spacing in the slab after annealing was measured to be 55 μm. The C element in the slab had an upward slope，the segregation coefficient became larger，the variation of the segregation coefficient was ?kC＝0.666. The Si element had a slight uphill diffusion，the variation of the segregation coefficient was ?kSi=0.041 5. The Mn element diffusion was more uniform，and the variation coefficient of the segregation coefficient was ΔkMn＝－0.141. The Cr element also diffused more uniformly and the variation coefficient of the segregation coefficient was ΔkCr＝－0.106. The simulation results showed that under the annealing condition of slab temperature of 680 ℃ and holding time of 2 h，C atoms were up-slope and diffuse，resulting in segregation. Si，Cr and Mn atoms had no obvious diffusion changes.
赵宜娜， 陈银莉， 余 伟， 王云龙， 范文生. 退火对齿轮钢枝晶偏析及元素扩散的影响[J]. 钢铁, 2019, 54(2): 60-66.
ZHAO Yi-na1， CHEN Yin-li2， YU Wei1， WANG Yun-long2， FAN Wen-sheng2. Effect of annealing on dendritic segregation and elemental diffusion of gear steel billet. Iron and Steel, 2019, 54(2): 60-66.
2019, Vol. 54 
