Strain-induced formation of a gradient nanostructured surface layer on an ultrahigh strength bearing steel
Strain-induced formation of a gradient nanostructured surface layer on an ultrahigh strength bearing steel
复制标题
DOI：
10.1016/j.jmst.2017.12.012
复制
发表时间：
2017-12
影响因子：
10.9
通讯作者：
Kuiliang Zhang;Z. B. Wang
中科院分区：
文献类型：
--
作者：
Kuiliang Zhang;Z. B. Wang
在本工作中，一个高强度轴承钢（AISI 52100）进行表面机械轧制处理（SMRT）在室温下。显微组织观察表明，马氏体板条，孪晶和马氏体颗粒在初始显微组织经历了明显的塑性应变，并逐渐细化为纳米结构。结果表明，在轴承钢表面获得了平均晶粒尺寸约为24nm的梯度纳米结构（GNS）表面层，表面硬度提高了20%。基于显微组织演变、相组成和深度硬度分布的分析揭示了GNS表面层的机械诱导形成机制。在SMRT过程中，轴承钢在良好润滑和冷却条件下发生了多表面剧烈塑性变形，形成了较厚的表面硬化层。
In the present work, an ultrahigh strength bearing steel (AISI 52100) was subjected to surface mechanical rolling treatment (SMRT) at room temperature. Microstructural observations showed that martensitic laths, twins and cementite particles in the initial microstructure underwent distinct plastic strains and were gradually refined into nanostructures. Consequently, a gradient nanostructured (GNS) surface layer with a mean grain size of ∼24 nm at the top surface was obtained on the bearing steel, resulting in an increment of ∼20% in the surface hardness. Analyses based on microstructural evolution, phase constitution and in-depth hardness distribution revealed a mechanically induced formation mechanism of the GNS surface layer. The multiple surface severe plastic deformation under fine lubrication and cooling during SMRT contributed to the formation of a thick hardened surface layer on the bearing steel.