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对采用“EBT→LF→VD”工艺路线生产50Cr5Mo V锻钢轧辊炼钢过程的全氧质量分数和夹杂物类型与数量进行了分析。结果表明:LF精炼后钢液中w(T[O])平均为0.004 7%,VD出站w(T[O])为0.001 4%,中间包w(T[O])为0.001 55%,铸坯w(T[O])为0.001 8%,轧材中w(T[O])降低至0.001 0%。LF精炼初期,钢中夹杂物主要是不规则的Al2O3夹杂,其中96.75%的夹杂物尺寸小于10μm。LF精炼结束后,大量夹杂物转变成以Ca O-Al2O3-Si O2为主要成分的0~1 0μm复合氧化物夹杂。钢水从VD真空精炼炉向中间包转移过程中,由于保护性浇注效果差,二次氧化严重造成钢水夹杂逐渐增多,其中夹杂物主要为球形的m Ca O·n Al2O3复合夹杂物。铸坯中99.65%的夹杂物尺寸小于10μm,其中大部分为球形钙铝酸盐夹杂物,还有少量球状硅铝酸钙复合夹杂物。轧材中98.77%的夹杂物尺寸小于10μm。通过对炼钢过程中各工序的工艺优化,可实现对夹杂物的有效控制,从而确保50Cr5Mo V合金铸钢的产品质量。
The oxygen mass fraction and the type and amount of inclusions in the steelmaking process of 50Cr5Mo V forging steel produced by adopting “EBT → LF → VD” process route were analyzed. The results show that the average w (T [O]) in molten steel after LF refining is 0.004 7%, the w (T [O] (T [O]) was 0.001 8%, and the w (T [O]) in rolled material was reduced to 0.001%. In the initial stage of LF refining, inclusions in steel are mainly irregular Al2O3 inclusions, of which 96.75% inclusions are smaller than 10μm. After the LF refining, a large amount of inclusions are transformed into 0 to 10 μm composite oxide inclusions mainly composed of Ca O-Al2O3-Si O2. During the transfer of molten steel from the VD vacuum refining furnace to the tundish, due to the poor protective casting effect, the serious secondary oxidation causes the molten steel inclusions to increase gradually, and the inclusions are mainly spherical m CaO · n Al2O3 composite inclusions. 99.65% of the inclusions in the cast slab are less than 10μm in size, most of which are spherical calcium aluminate inclusions, and a small amount of globular calcium aluminate calcium composite inclusions. 98.77% of the inclusions in the rolled material have a size of less than 10 μm. By optimizing the process of each process in the steelmaking process, effective control of the inclusions can be realized to ensure the product quality of the 50Cr5MoV alloy steel.