立方氮化硼刀具切削高温镍基合金的原位力学行为特征及磨损机理研究

High-speed dry machining of nickel-based alloy and titanium-based alloy is the cutting edge in green manufacturing. Currently issue of rapid tool wear is the key obstacle in the green machining of these alloys. In previous research a number of microscale wear models has been established based on the tool performance and cooling conditions. However, with the consideration of the substantial influence of micromechanical properties from inclusions in the in-situ environment, it is of a great scientific significance to reveal the mechanism of tool wear related to in-situ mechanical properties. Based on previous study, the proposed project will investigate in-situ mechanical behavior and their correlation with tool wear in machining of high-temperature nickel-based alloy by cubic boron nitride (CBN) insert, aiming to propose a novel method which can measure the in-situ mechanical properties quantitatively and its distribution in the material. In addition, with comprehensive technologies of high-speed machining by CBN and ultra-deep depth 3D profile microscopy, the study will also measure 3D wear profile in microscale along the cutting edge, and establish a new 3D multi-parameters tool wear pattern and wear prediction model. Moreover, with the combination of in-situ mechanical properties and tool wear results, this study will establish a microscale mechanic model in relation to machining, squeezing and sliding to reveal the wear mechanism of CBN insert in machining of nickel-base alloy, and the tool wear pattern and tool life prediction model. Obtained results from the project will greatly provide a fundamental theory in the development of new CBN tool and tool selection; it will also contribute to the process optimization and ultimately enhance the processing stability in manufacturing.

高温镍基合金、钛合金等材料的高速干切削机理是清洁切削前沿，其刀具磨损机理是核心问题之一。国内外大量研究从刀具性能和冷却条件方面建立了微观尺度刀具磨损模型，但考虑到工件材料中原位环境对微观硬质点的力学性能影响极大，从原位力学行为特征的角度揭示刀具磨损机理具有重要的科学意义。结合课题组在刀具磨损的微观力学前期基础，以立方氮化硼(CBN)刀具切削高温镍基合金为对象，研究原位力学行为特征对刀具的磨损机理。本项目提出阵列式纳米压痕技术测定材料原位力学性能的新方法；综合高速切削试验和超景深显微技术，获得刀具沿切削接触区的微观磨损形貌，以此构建三维多参数刀具微观磨损表达模型；综合分析微观结构原位力学和刀具磨损结果，建立微观切削、挤压、滑移的力学模型，揭示CBN刀具切削高温镍基合金的原位力学行为特征及磨损机理，建立材料微观原位力学表达的刀具磨损和寿命预测模型；为指导刀具设计、选择和加工过程稳定奠定基础。

本项目针对高温镍基合金、钛合金等材料的高速干式切削进行了研究，以立方氮化硼(CBN)刀具切削高温镍基合金为对象，研究原位力学行为特征对刀具的磨损机理。本项目提出阵列式纳米压痕技术测定材料原位力学性能的新方法；综合高速切削试验和超景深显微技术，获得刀具沿切削接触区的微观磨损形貌，以此构建三维多参数刀具微观磨损表达模型；综合分析微观结构原位力学和刀具磨损结果，建立微观切削、挤压、滑移的力学模型，揭示CBN刀具切削高温镍基合金的原位力学行为特征及磨损机理，建立材料微观原位力学表达的刀具磨损和寿命预测模型，完成了对刀具磨损相关机理的论证。本研究从微观原位力学性能作用的下刀具磨损机理，进行了阵列式的纳米压痕测试，从统计学角度获取了微观硬质点和基体结构的硬度统计学差异并且建立了刀具磨损相关联的磨蚀性磨损模型。通过干式切削和半干式切削的测试实验，磨蚀性模型可以准确的表达刀具磨损和磨蚀性的关联关系，其作用机理是微观磨蚀性的增加从而造成立方氮化硼刀具（CBN）刃口的磨损加剧，从而增大了刃口半径而提高了切削力和切削热，随着刃口钝化的加剧，刀具快速进入了失效模式从而造成了刀具的刃口崩刃及沟槽磨损。同时本研究工作也对镍基合金和钛基合金加工的残余应力进行了研究，采用正交实验证实残余应力对原位力学性能具有较大的影响，其主要纳米压痕压头在压入被测表面时，在亚表面形成了堆积效应。通过有限元仿真和大量阵列式纳米压痕测试对残余应力影响进行了建模，并且可以准确获取残余应力大小和对原位力学性能的修正，进而提升了原位力学性能测量的准确度。通过的原位力学性能和刀具磨损的研究，提出了干式或半干式切削加工刀具的改进方向。从微量润滑、微织构和复合涂层等方面进行了CBN刀具高效加工高温镍基合金的绿色制造方案，同时针对高温镍基合金加工，提出了可自定义优化目标的刀具选择方案，实现了高温合金材料加工的CBN刀具智能选择策略，为高端装备制造提供了应用基础。