钙处理对涟钢高强机械用钢夹杂物的影响

对涟钢LG600/LG700XL冶炼过程中夹杂物的衍变机理进行分析,分批次试验研究了精炼渣性能和钙处理工艺对钢液洁净度和钢中夹杂物的影响。结果表明,在钙处理工艺下,夹杂物的衍变路线为Al_2O_3→MgO-Al_2O_3→Al_2O_3-CaO,中间包钢液中的夹杂物主要是Al_2O_3-CaO和Al_2O_3-TiO_x复合氧化物。取消钙处理以后,铸坯中氧的质量分数从16×10~(-6)降低到11×10~(-6)。两种工艺下,材样中绝大部分夹杂物都是核心为铝酸盐、外层为TiN的复合夹杂,钙处理工艺下夹杂物核心是Al_2O_3-CaO-CaS,取消钙处理工艺下夹杂物核心是MgO-Al_2O_3尖晶石。两类复合夹杂物尺寸都比较小(10μm),对钢材性能的影响有限。取消钙处理以后,钢液可浇性基本保持不变,没有发生水口堵塞,说明取消精炼过程中的钙处理工艺对涟钢高强机械用钢而言是可行的。

Effect of calcium treatment on inclusions of high strength machinery steel of Lianyuan Steel Company

The evolution mechanism of inclusions in LG600/LG700XL engineering machinery high strength steel during steelmaking was analyzed,and the effects of refining slag and calcium treatment on inclusion and steel cleanliness were researched.The results showed that the inclusion evolution route through calcium treatment.was Al2O3→MgO-Al2O3→Al2O3-CaO,and the inclusions in liquid steel in tundish were mainly the complex oxides of Al2O3-CaO and Al2O3-TiOx.The mass fraction of oxygen decreased from 16 x 10-6 to 11 × 10-6 when calcium treatment was cancelled.Inclusions of steel product through the two production processes were both mainly complex inclusions of aluminate as core and TiN as outer layer,while the core of inclusion with the process of calcium treatment was Al2O3-CaO-CaS and without calcium treatment was MgO-Al2O3.The sizes of these complex inclusions were all small (＜ 10 μmn),which had limited impact on steel quality.The steel castability after cancelling calcium treatment was the same as before on the whole and there was no nozzle clogging,which indicated that cancelling calcium treatment in refining was feasible for engineering machinery high strength steel in LY Steel.