20MnCr5齿轮钢全流程夹杂物分析

Analysis of inclusions in the whole process of 20MnCr5 gear steel

为有效改善齿轮钢的洁净度,提高产品质量,必须明确齿轮钢冶炼过程中非金属夹杂物的演变行为。以某厂20MnCr5齿轮钢为研究对象,通过对LF-VD-CC工艺齿轮钢生产过程的全流程取样分析,利用扫描电子显微镜对冶炼过程不同阶段的夹杂物成分、形貌、尺寸和数量等特性进行系统分析研究。结果表明,LF进站时,主要夹杂物为Al_(2)O_(3)-MnS复合夹杂物,其中还分布了大量的MnS夹杂物;精炼20 min后取样,观察到Al_(2)O_(3)-MgO-MnS复合夹杂物和Al_(2)O_(3)夹杂物;LF末期,产物基本不变;VD破空后,观察到的主要夹杂物为MnS夹杂物和呈近球形的以Al_(2)O_(3)为核心的MnS包裹的复合夹杂物,还有许多镁铝尖晶石,其有的含有少量CaO,有的有少量MnS,但主要成分为镁铝尖晶石。针对该钢厂镁铝尖晶石较多的情况,可通过调控精炼渣或者减少耐火材料的侵蚀进行改善。

In order to effectively improve the cleanliness of gear steel and product quality,it is necessary to clarify the evolution behavior of non-metallic inclusions in the smelting process of gear steel.This paper takes 20MnCr5 gear steel as the research object.Through sampling and analysis of the whole LF-VD-CC gear steel production process,a scanning electron microscope is used to systematically analyze the characteristics of inclusion composition,morphology,size,and quantity at different stages of the smelting process.When LF enters the station,the primary inclusions are Al_(2)O_(3)-MnS composite inclusions,among which many MnS inclusions are distributed.After 20 minutes of refining,Al_(2)O_(3)-MgOMnS composite and Al_(2)O_(3)inclusions were observed.At the end of LF,the product is unchanged.After VD breaking,the primary inclusions observed are MnS inclusions,which are nearly spherical and consist of MnS inclusions with Al_(2)O_(3)as the core.There are many magnesia-aluminum spinels,some of which have a small amount of CaO,and some have a small amount of MnS.However,the main component is the magnesia-aluminum spinel.