20CrMnTiH钢中残余硼对末端淬透性的影响及工艺控制

Effect of Residual Boron on Jominy Hardenability of 20CrMnTiH Steel and Process Control

通过对特钢厂经110 t电弧炉+LF/VD精炼+连铸+热连轧工艺流程生产的400炉钢棒材的数据进行统计,利用末端淬透性实验[(920±10)℃50 min后空冷至室温,随后(880±5)℃30 min水淬]和光谱分析获得了20CrMnTiH系列钢的淬透性和化学成分,发现淬透性与残余硼元素存在线性关系。通过对各冶炼工序的分析,得出钢中B的主要来源是电弧炉下渣,控制电弧炉出钢下渣量,可以有效控制钢中B含量。此外,还须将精炼渣中Al_(2)O_(3)含量从~30%降至15%~20%,可将钢中B含量控制在0.0002%以下。

The experimental data of 400 heats of steel produced by 110 t EAF+LF/VD refining+continuous casting+hot rolling in a special steel plant are statistically analyzed.The hardenability[at(920±10)℃for 50 min and then air cooling to room temperature,followed by holding at(880±5)℃for 30 min water quenching]and chemical composition of 20CrMnTiH steel are obtained by means of Jominy test and spectral analysis to get a linear relationship between the hardenability and the content of residual boron.By each steelmaking practice analysis it is found that the main source of B in steel is EAF tapping slag.The content of B in steel can be effectively controlled by controlling the amount of tapping slag in EAF tapping.In addition,when the amount of Al_(2)O_(3) in the refining slag decreases from 30%to 15%~20%,the content of B in steel can be controlled below 0.0002%.