Wear Mechanism of Cemented Carbide Tool in High Speed Milling of Stainless Steel

Adhesion of cutting tool and chip often occurs when machining stainless steels with cemented carbide tools. Wear mechanism of cemented carbide tool in high speed milling of stainless steel 0Cr13Ni4 Mo was studied in this work. Machining tests on high speed milling of 0Cr13Ni4 Mo with a cemented carbide tool are conducted. The cutting force and cutting temperature are measured. The wear pattern is recorded and analyzed by high?speed camera, scanning electron microscope(SEM) and energy dispersive X?ray spectroscopy(EDS). It is found that adhesive wear was the dominant wear pattern causing tool failure. The process and microcosmic mechanism of the tool’s adhesive wear are analyzed and discussed based on the experimental results. It is shown that adhesive wear of the tool occurs due to the wear of coating, the a nity of elements Fe and Co, and the grinding of workpiece materials to the tool material. The process of adhesive wear includes both microcosmic elements di usion and macroscopic cyclic process of adhe?sion, tearing and fracture.

Study on Interface Structure and Bond Properties between Cemented Carbide and Tool Steel Blazing with amorphous alloy

Cemented Carbide YG11C and Tool Steel Crl2MoV was blazed with Ni-base amorphous alloys, QG-1011, MBF-20 and MBF-75, using dynamics thermodynamics analogue testing machine Gleeble 1500D. The effects of brazing temperature, holding time and holding pressure on micro-structure and bond strength were investigated. Results showed that YG11C and Crl2MoV were all wetted well by these three Ni-base alloys, and the bond strength was as high as 220MPa, 320MPa, 320MPa respectively. When the blazing temperature was at the point over the melting point 60-70°C of Ni-base alloy, the holding time was about 2-10min, the suitable pressure was benefit for improving the brazing quality. Microanalysis showed Co in cemented carbide diffused into liquid brazing alloy and formed the Fe-Co solid .solution.

Analysis on the Wear Performances of Cemented Carbide Tools Containing Ti in the Coatings When Machining Ti⁃6Al⁃4V Alloys

Because of the high affinity of the same element Ti,cemented carbide tools containing Ti seem to be non⁃optimal in machining titanium alloys.However,in practice,cemented carbide tools containing Ti are still widely used in machining titanium alloys.Cutting experiments were conducted in order to systematically explain the contradictions between the practice and theory.The diffusion process between titanium alloys and the cemented carbide tools was analyzed by auger electron spectroscopy detecting the cutting regions.It was also analyzed by Ti/Co diffusion behavior simulated by molecular thermodynamics.The experimental results and the simulation results showed that the mutual diffusion of Ti/Co atoms was the major reason for the diffusion wear.The dissolution⁃diffusion wear was one of the main wear mechanisms for the cemented carbide tools containing Ti in the coatings.Moreover,four types of cemented carbide tools and two other types of cermet tools were used to machine the Ti⁃6Al⁃4V alloys at different cutting speeds to further verify the high affinity of cutting tools containing Ti in the substrate/coating.The verification experiments results showed that the cemented carbide tools containing Ti generally cannot be used for machining titanium alloys,but could show less affinity in the cutting regions with reasonable cutting conditions.

An Analysis of the Structure of Carbide-tool Utilization Expert System

The necessity and feasibility of an expert system for carbide-tool utilization are analyzed and a practical system named CUES(carbide-tool utilization expert system ) is developed and realized. The system concept, module structure, data management, inference strategy and the interface design of the system are discussed in.detail. The system would be useful not only for the preparation of tool bank of FMS or CIMS, but the for the proper application of cemented carbide tools in conventional machining Processes.

Failure Mechanism of CVD Coated Carbide Tools

Through systematically theoretical analysis and experimental research,the failure mechanism,of CVD(chemical vapor deposition) coated carbide tools in wear and fracture conditions was studied.On the basis of mechanism analysis,the specific suitability of the coated tools for cutting conditions was revealed and clarified.

Cutting Performance and Mechanism of RE Carbide Tools

The research of rare earth elements (RE), added into cemented carbide tools, is one of the recent developments of new types of tool materials in China. Systematic experiments about RE carbides YG8R. (K30), YT14R (P20) and, YW1R (M10) were made to study on the cutting performance in comparison with non-RE carbides YG8, YT14 and YW1. The cutting experiments were as follows: tool life, cutting force, tool-chip friction coefficient and interrupted machining. The action of RE on the carbide materials and the cutting mechanism of the RE carbide tools in the cutting process were verified with the aid of SEM and energy spectrum analysis. Experimental results show that the RE carbide tools have a good overall performance.

Adhesion Wear of Carbide Tool when Machining GH 907

The adhesion wear of cemented carbide tool when machining GH907 was studied with white light interferometer,infrared imaging,and SEM-EDS.The adhesion wear morphology,wear mechanism and the wear rule of adhesion were analyzed,and the effect of different cutting time and different cutting speed on adhesive wear were analyzed.The conclusion will provide useful references for the optimization of cutting parameters and the improvement of the tool life.

Microstructure and mechanical properties of titanium nitride coatings for cemented carbide cutting tools by pulsed high energy density plasma

Hard, wear-resistant and well-adhesive titanium nitride coatings on cemented carbide cutting tools were prepared by the pulsed high energy density plasma technique at ambient temperature. The results of Auger spectra analysis indicated that the interface between the coating and substrate was more than 250 nm. Under optimized deposition conditions, the highest critical load measured by nanoscratch tester was more than 90 mN, which meant that the TiN film was well adhesive to the substrate; the highest nanohardness and Young抯 modulus according to nanoindentation tests were near to 27 and 450 GPa. The results of cutting tests evaluated by turning hardened CrWMn steel in industrial conditions indicated that the wear resistance and edge life of the cemented carbide tools were enhanced dramatically because of the deposition of titanium nitride coatings. These improvements were attributed to the three combined effects: the deposition and ion implantation of the pulsed plasma and the becoming finer of the grain sizes.

Zhuzhou Cemented Carbide: Dedicated to Aerospace Cutting Tools, Contributive to Manufacturing Transformation and Upgrading

Zhuzhou Cemented Carbide Cutting Tools Co.,Ltd(hereinafterreferredtoas'Zhuzhou Cemented Carbide'), established in June, 2002,is located in National-level High-tech Industry Development Zone in Zhuzhou, Hunan. Being domesticleadingcomprehensivecemented carbidecuttingtoolsupplier,Zhuzhou CementedCarbidehasalsosetupwhollyowned sales subsidiaries in USA and German,integrating production, sales and R&D.

Laser-induced oxidation assisted micro milling of high aspect ratio microgroove on WC-Co cemented carbide

Severe tool wear and poor surface quality are the main problems during micro machining of cemented carbide.In this work,an innovative hybrid process of laser-induced oxidation assisted micro milling(LOMM)was proposed to solve the problems.A nanosecond laser was utilized to induce oxidation of the WC-20%Co material,producing loose oxide which was easy to remove.The micro machinability of the material was improved by laser-induced oxidation.The oxidation mechanisms of cemented carbide were studied.A microgroove with a depth of 2.5 mm and aspect ratio of 5 was fabricated successfully.The milling force,surface quality and tool wear mechanisms were investigated.For comparison,a microgroove was also fabricated with conventional micro milling(COMM)using identical milling parameters.Results revealed that in LOMM the milling force and tool wear rate were extremely low during removing the oxide.The machined surface quality and dimensional accuracy achieved by LOMM were superior to those obtained by COMM.The surface roughness Saof the microgroove bottom reached 88 nm in LOMM,while the cross-sectional geometry of the microgroove was a trapezoid.Perpendicularity of the microgroove sidewall machined by LOMM was better than that by COMM.The tool wear forms in LOMM were coating spalling and slight tool nose breakage.Compared with COMM,the tool life in LOMM was prolonged significantly.It indicates that the proposed hybrid process is an effective and efficient way to fabricate high aspect ratio micro-features with high dimensional accuracy.

High-Speed Machining of Malleable Cast Iron by Various Cutting Tools Coated by Physical Vapor Deposition

The coating material of a tool directly affects the efficiency and cost of machining malleable cast iron.However,the machining adaptability of various coating materials to malleable cast iron has been insufficiently researched.In this paper,turning tests were conducted on cemented carbide tools with different coatings(a thick TiN/TiAlN coating,a thin TiN/TiAlN coating,and a nanocomposite(nc)TiAlSiN coating).All coatings were applied by physical vapor deposition.In a comparative study of chip morphology,cutting force,cutting temperature,specific cutting energy,tool wear,and surface roughness,this study analyzed the cutting characteristics of the tools coated with various materials,and established the relationship between the cutting parameters and machining objectives.The results showed that in malleable cast iron machining,the coating material significantly affects the cutting performance of the tool.Among the three tools,the nc-TiAlSiN-coated carbide tool achieved the minimum cutting force,the lowest cutting temperature,least tool wear,longest tool life,and best surface quality.Moreover,in comparisons between cemented-carbide and compacted-graphite cast iron machined under the same conditions,the wear mechanism of the coated tools was found to depend on the cast iron being machined.Therefore,the performance requirements of a tool depend on multiple factors,and selecting an appropriately coated tool for a particular cast iron material is essential.

切削镍基高温合金Ni、Fe、Cr原子在WC-Co硬质合金刀具中的扩散机制及对刀具性能的影响

在切削镍基高温合金过程中,采用第一性原理计算研究了Ni、Fe、Cr原子扩散进入WC-Co硬质合金刀具后对刀具所产生的影响,分析了刀具结合能、晶格畸变、电子性质、扩散过渡态、扩散系数、力学性质的变化。研究结果表明,原子在不同间隙位置的结合能都为负值,八面体间隙所引发的晶格畸变更低。Ni、Fe、Cr原子增强了硬质合金WC-Co的金属性,但不利于原子之间的成键,使其机械稳定性降低;三种原子扩散势垒分别为0.82、0.79、1.17 eV,扩散系数的大小关系为D Fe>D Ni>D Cr。实验结果与理论计算相吻合,且实验现象表明元素扩散导致刀具切削性能下降,易诱发刀具的磨粒磨损。

电场处理对YG8硬质合金及其刀具性能的影响

为探索一种高效的硬质合金强化处理技术,研究了电场处理对YG8硬质合金显微组织及性能的影响,采用TEM、SEM等对电场处理前后的YG8硬质合金试样及其刀具进行微观组织分析,采用维氏硬度计进行力学性能测试,数控车床进行切削加工实验。结果表明:经电场处理后,YG8硬质合金试样断裂韧性有所增大,其刀具切削性能得到提升,且电场处理刀具的被加工工件表面质量明显得到提高。在脉冲电流作用下,材料会发生电塑性效应,为位错运动提供驱动力,使位错更容易进行增殖和滑移,位错密度增加,从而有利于材料性能的提高。当脉冲电流为15 A/mm^(2)时,断裂韧性达到最大值9.41 MPa·m^(1/2),相比于未使用电场处理的断裂韧性提高了近10%。经电场处理的YG8硬质合金刀具在切削过程中切削温度降低,可有效防止积屑瘤产生,改善切削过程的摩擦状态,保证了切削质量,使得被加工工件表面质量明显提高。

硬质合金在井下工具中的应用与关键技术分析

硬质合金作为一种常用的高硬度材料,具有良好的耐温性与耐磨性,在井下工具中的应用非常广泛,具有良好的发展前景。文章在阐述当前硬质合金主要类别和研究现状的基础上,调研分析了硬质合金材料在井下工具常见零部件中的应用现状,重点分析了目前钻探行业对硬质合金材料的性能需求,提出了在地球深部高温钻探领域,井下工具所用硬质合金材料的关键技术,为硬质合金材料在钻探行业的应用与发展提供参考。

硬质合金刀具皮秒激光加工表面形貌及成分变化研究

聚焦于硬质合金皮秒激光加工表面成分变化特性,研究了不同激光能流密度对硬质合金表面形貌、粗糙度、材料去除特性和化学成分的影响,重点讨论了烧结WC-Co硬质合金在皮秒激光加工前后的表面特性,获得不同能流密度激光与WC-Co材料的作用机制,结果表明,在低能流密度下,激光与WC-Co的作用机制主要是浅表层熔化机制,属于激光抛光,在WC-Co刀具激光加工中可用作精加工工序;在高能流密度下,激光与WC-Co的作用机制主要在材料深度方向稳定去除,在WC-Co刀具激光加工中可用作粗加工工序。本研究为WC-Co刀具的激光加工提供了理论参考和数据支持。

套磨铣工具硬质合金耐磨层制备工艺研究进展

套磨铣工具是井下修井的重要装备,随着我国石油工程井下作业越来越多,对套磨铣工具的性能和使用寿命提出了更高要求。本研究系统介绍了目前国内外硬质合金耐磨层制备方法的研究进展,针对具有较好应用前景的制备方法进行了分析,包括激光熔覆、电弧焊、等离子焊以及钎焊等,重点对硬质合金和填充材料的成分开发、焊接工艺优化进行了深入探讨,为未来套磨铣工具强化材料及其加工工艺发展提供参考。

等离子烧结工艺对WC/Cr_(3)C_(2)/La_(2)O_(3)刀具材料力学性能的影响

针对传统硬质合金刀具高速切削过程中粘结相易于磨损等问题,采用放电等离子烧结制备了WC/Cr_(3)C_(2)/La_(2)O_(3)刀具材料,研究了Cr_(3)C_(2)添加量(质量分数,0%~2.00%)和工艺参数(烧结温度1500~1700℃,烧结压力15~45 MPa)对刀具材料微观组织和力学性能的影响。结果表明,添加质量分数0.50%的Cr_(3)C_(2)并在1550℃和25 MPa条件下烧结,得到的WC/Cr_(3)C_(2)/La_(2)O_(3)刀具材料相对密度、抗弯强度和硬度分别为97.5%、1281.0 MPa和HV 2124.3。随着烧结温度增加,材料的相对密度增加,微观组织逐渐均匀;但过高温度会导致晶粒异常长大,组织分布不均,孔隙增多,综合力学性能下降。随着烧结压力增加,材料晶粒细小,组织更加均匀,力学性能增加;但当压力超过25 MPa后,材料力学性能有所下降。

复合材料半自动制孔刀具结构设计与试验研究

采用传统硬质合金刀具对碳纤维复合材料进行半自动制孔时容易产生烧伤、分层、撕裂等质量缺陷,本文对刀具材料和结构进行优化设计,提出一种PCD钻头和台阶式PCD扩孔钻,通过开展PCD和硬质合金刀具半自动制孔试验,分析孔壁温度、刀具磨损及出孔面质量,得出该刀具具有切削热量低、轴向力和径向力小的特点,能够减少碳纤维过热、烧伤和出孔面分层、撕裂的风险。

基于硬质合金钎焊技术的刀具刃口修复研究

当刀具刃口受到高强度冲击会出现崩口、断裂、磨损等破坏,为提高刃口剪切强度和修复后的外观效果,研究基于硬质合金钎焊技术的刀具刃口修复技术。使用主要成分为碳化钨的YG8硬质合金作为母材,确定钎料及钎剂后,在钎焊设备的作用下修复刀具刃口。通过万能试验机测试不同降温方法、不同焊缝宽度以及不同升温速率下修复后机械设备刀具刃口性能。试验结果显示,石膏粉冷却刀具后,采用硼砂处理多余钎剂的方式能够提升刃口剪切强度,且该方法修复后的刃口外观良好,焊缝宽度小于0.1mm,升温速率为30℃/s时,修复后刀具刃口剪切强度较高,修复效果较好。

硬质合金涂层刀具研究的新进展

随着现代机械加工工业朝着高精度、高速切削、干式切削技术以及降低成本等方向发展,人们对硬质合金刀具提出了更高的要求。涂层硬质合金具有高硬度和优良的耐磨性,延长了刀具的寿命,这是切削刀具发展的又一次革命。本文综述了目前国内外硬质合金涂层刀具在涂层方法、涂层种类和涂层基体等方面的新进展。