Abstract

The structure of grade-U8 steel after high speed processing by deforming cutting is studied. The phase composition and structural features of a hardened surface layer comprised of separate areas (so called ribs) in close with each other are established. While applying the methods of optical and electron microscopy in the near-tool bit area of the rib, the following features are detected: nonequilibrium ferrite and coarse acicular martensite with crystal sizes of about 100 nm, parquet martensite-like structures with plate widths of tens of nanometers, as well as cementite crystals of various sizes from 10 to 100 nm. Such a heterogeneous structural state occurs in the rib area in contact with the tool bit during processing by deforming cutting. The structure of the opposite rib area is cardinally different and comprised of equiaxed ferrite grains with a size of ~500 nm and with fine boundary depositions (presumably carbides) with a size of 10–20 nm.

中文翻译：

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U8级钢变形切削加工后的表面结构

摘要

研究了U8钢的变形切削高速加工后的组织。建立了由彼此靠近的单独区域（所谓的肋）组成的硬化表面层的相组成和结构特征。当在肋骨的近工具钻头区域应用光学和电子显微镜方法时，会发现以下特征：非平衡铁素体和粗针状马氏体，晶体尺寸约为100 nm，镶木地板状马氏体结构，板宽为数十纳米，以及尺寸从10到100 nm的渗碳体晶体。这种异质结构状态在加工中通过使切削变形而在与刀头接触的肋区域中产生。