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为了保证含硫钢的切削性能,同时改善Mn S对钢材造成的各向异性,通常对Mn S进行变性处理。对含硫钢分别进行了镁处理和钙处理试验,分析了这两种处理方式对钢中夹杂物尺寸和成分的影响。镁处理有利于在钢中形成更加细小的Mg-Al-O氧化物夹杂。在钢液凝固过程中,Mg-Al-O夹杂可以作为Mn S的形核核心,减少Mn S沿晶界析出的数量;Mg-Al-O氧化物核心外围包裹的Mg-Mn-S中的镁主要来源于氧化物核心中的镁向外层Mn S中的扩散。钢经过钙处理后,形成的Ca-Al-O氧化物作为Mn S的形核核心;氧化物核心外围包裹的Ca-Mn-S主要是由钢液中溶解的钙进入外层包裹的Mn S中所形成;复合硫化物中的钙进一步向氧化物核心中扩散,使核心中钙质量分数逐渐升高。
In order to ensure the machinability of sulfur-containing steel and to improve the anisotropy caused by MnS to steel, MnS is usually denatured. The sulfur-containing steel was respectively treated with magnesium and calcium, and the influence of these two treatments on the size and composition of inclusions in steel was analyzed. Magnesium treatment favors the formation of finer Mg-Al-O oxide inclusions in the steel. During the solidification of molten steel, Mg-Al-O inclusions can be used as nucleation sites of MnS to reduce the amount of MnS precipitated along the grain boundaries. In Mg-Mn-S surrounded by Mg-Al-O oxide cores Magnesium mainly comes from the diffusion of magnesium in the oxide core into the outer layer MnS. After calcium treatment, the Ca-Al-O oxide formed was the core of MnS. The Ca-Mn-S encapsulated in the oxide core was mainly composed of Ca In the complex sulfide in the further diffusion of calcium to the oxide core, so that the core of the calcium mass fraction gradually increased.