离心铸造高硼高速钢辊环组织及性能研究

摘要

针对高速钢轧辊生产成本高的问题,设计一种用廉价硼元素部分取代昂贵合金元素的新型耐磨材料,离心铸造出辊环.借助扫描电镜(SEM)和X射线衍射(XRD)等手段对高硼高速钢辊环组织进行了研究,为高硼高速钢复合轧辊生产奠定基础.结果表明:铸态高硼高速钢辊环组织由马氏体、少量残余奥氏体及硼碳化物组成,硼碳化物由M2(B,C),(W,Mo)2(B,C),M3(B,C)以及M23(B,C)6组成,呈鱼骨状、筛网状和块状沿晶界分布；快速冷却下,辊环径向上合金元素无偏析.经1 050℃水淬后,共晶硼碳化物形貌和分布没有变化,部分二次硼碳化物溶解,局部有断网现象,基体中出现细小、弥散的二次析出物,经525℃回火后数量明显增加.热处理后,硬度达到HRC60.8,冲击韧性可达到8.4 J/cm2.%Aiming at the high production costs of high speed steel roll, a new kind of wear-resistant material was designed through adding the cheap boron elements to partly replace expensive element, and roll ring was produced by centrifugal casting. The microstructure of high boron high speed steel roll ring was researched by means of scanning electron microscopy and X-ray diffraction, etc, which laid a foundation for high boron high speed steel composite rolls. The results show that as-cast high boron high speed steel roll ring comprises martensite, a small amount of residual austenite and borocarbides. Borocarbides consisting of M2 (B,C),(W,Mo)2 (B,C), M3 (B,C )and M23 (B,C )6 are distributed in fishbone, screen and bulk along the grain boundaries. Under rapid cooling, there is almost no segregation of alloying elements. After water quenching at 1 050 ℃ , the morphology and distribution of eutectic borocarbides do not change. Some secondary borocarbides dissolve, and broken borocarbides are found. The tiny and diffuse second precipitation appears in the matrix; the amount of second precipitation increases significantly after tempered at 525 ℃. After heat treatment, hardness achieves HRC 60.8, and impact toughness can achieve 8.4 J/cm2.