Ti-Ca复合脱氧大线能量焊接用钢中夹杂物的演变

 为了更好地掌握氧化物冶金生产工艺，通过工业试验和热力学计算研究了Ti-Ca复合脱氧工艺生产大线能量焊接用钢全流程夹杂物成分、尺寸、数量的演变规律。LF进站时钢中夹杂物主要类型为硅锰氧化物类夹杂，Ti-Ca复合脱氧后转变为CaO-Al2O3-TiOx-MgO-SiO2，精炼过程夹杂物中铝质量分数降低，而钙和钛质量分数升高，最终轧板中典型夹杂物为CaO-Al2O3-SiO2、CaO- TiOx、Ca（Mn）S、TiN的复合多相夹杂物。LF-RH整个精炼过程中，钢中夹杂物体积比整体在不断下降，连铸过程又有所升高，最终轧材中夹杂物的体积比约为2.6×10－5。Ti-Ca复合脱氧与RH精炼对夹杂物的细化作用明显，轧材中尺寸为0～1 μm夹杂物占到了约73%，尺寸大于3 μm的仅约占5%。100和200 kJ/cm线能量下模焊后热影响区－40 ℃的冲击功平均值分别为275和209 J，腐蚀后发现了以夹杂物为核心形核长大的针状铁素体。

Evolution of inclusions in high heat input welding steel with Ti-Ca compound deoxygenation

In order to better master the production process of oxide metallurgy，the evolution law of the composition， size and quantity of inclusions in the high heat input welding steel full production process with the Ti-Ca composite deoxygenation was studied by industrial experiments and thermodynamic calculations. At the beginning of the LF refining， the main type of inclusions was silicon manganese oxide； after the Ti-Ca compound deoxygenation， it changed into CaO-Al2O3-TiOx-MgO-SiO2； the mass percent of Al in the refining process decreased， while the mass percent of Ca and Ti increased； in the final steel plate， the typical styles of inclusions were CaO-Al2O3-SiO2， CaO-Ti2O3， Ca（Mn）S， TiN composite polyphase. In the whole refining process of LF-RH， the integral number of inclusions decreased continuously， while the tendency of the continuous casting process was opposite； the volume percent of inclusions in the final steel plate was about 2.6×10－5. The effect of Ti-Ca compound deoxygenation and RH refining on inclusions evolution was obvious； the percentage of 0-1 μm inclusions in the plate was about 73%， while that of ＞3 μm inclusions was only ab- out 5%. After 100 and 200 kJ/cm line energy welding simulations， the average impact work values at －40 ℃ of HAZ were 275 and 209 J respectively； acicular ferrites with a core of inclusions were found after corrosion.