Abstract

Nano-bainitic steels have attracted great attention for good wear resistance. In this research, a medium-carbon low-alloyed steel was austempered at a low temperature close to its martensite-start temperature for various times to obtain mixed microstructure of nano-bainite, martensite and retained austenite. The austempered samples were characterised comprehensively by field-emission SEM and quantitative XRD. Its two-body abrasive wear property was evaluated by sliding on a SiC abrasive disc. The results revealed the formation of initial nano-width carbide-free bainitic ferrite (BF) after austempering by 10 min, whereas the BF size and amount both increased with the austempering time. The austempered samples exhibited wear coefficients lower than the quenched martensitic sample by up to 50%. SEM and TEM observations showed wear mechanisms of micro-cutting and ploughing deformation, including the formation of a nano-laminate top layer and bending deformation in the subsurface multiphase microstructure. The decreased wear loss was attributed to the role of retained austenite in the increased plasticity.

Graphic abstract

中文翻译：

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短期低温奥氏体回火对中碳低合金钢组织和磨耗的影响

摘要

纳米贝氏体钢因其良好的耐磨性而备受关注。在这项研究中，将中碳低合金钢在接近其马氏体起始温度的低温下进行了多次奥氏体化处理，以获得纳米贝氏体，马氏体和残余奥氏体的混合组织。通过场发射扫描电镜和定量X射线衍射对奥氏体样品进行了全面表征。通过在SiC磨盘上滑动来评估其二体磨料的磨损性能。结果表明，奥氏体回火10 min后会形成初始的纳米级无碳化物贝氏体铁素体（BF），而BF的大小和数量均随奥氏体回火时间而增加。奥氏体样品的磨损系数比淬火马氏体样品低50％。SEM和TEM观察显示了微切割和犁形变形的磨损机制，包括纳米层压顶层的形成和地下多相微结构的弯曲变形。磨损量的减少归因于残余奥氏体在增加塑性方面的作用。

图形摘要