为了改善高速钢表面的摩擦磨损性能,采用钻削加工的方法,在45钢表面加工出不同深度的凹坑织构,进行凹坑织构表面与GCr15的摩擦磨损试验,测量了摩擦系数和磨损量,观察了试件磨痕表面,分析了凹坑体积对织构表面摩擦磨损性能的影响.结果表明:凹坑织构表面的摩擦系数和磨损量首先随着凹坑体积的增加而减小,当凹坑体积达到某一值后,摩擦系数和磨损量不再随着体积的增加而减小;凹坑织构的容屑作用有助于提高织构表面的摩擦磨损特性;45钢在磨损过程中存在磨屑的搭桥覆盖现象,影响了凹坑的容屑能力,限制了凹坑织构表面耐磨性能的提高.

The mechanism of attachment of wear debris to textured dimples was investigated experimentally. Textured dimples were fabricated on the surface of medium carbon steel specimen with drilling method. Reciprocating ball on disc sliding wear experiments were carried out. The dimples trapped with wear debris and worn surfaces were observed with microscope. Tribo-magnetization of wear debris was employed to explain the attachment of debris in dimples. The size of wear debris and magnetic flux density of worn surfaces were measured. Wear experiments processes were also carried out under degaussing conditions. The experimental results show that tribo-magnetization causes the phenomena of attachment and bridging of wear debris to edge of textured dimples. By applying degaussing method, attachment of wear debris within textured dimples can be reduced. For comparison, coefficients of friction, wear mass loss of specimens and wear volume loss of mating balls were measured under both conditions of non-degaussing and degaussing. Degaussing can be beneficial to improve the capacity of trapping wear debris of textured dimples for ferromagnetic materials, and to improve the wear resistance of dimple textured specimen.

With the factorial design experiment, the influences of laser process parameters on hole taper and heat affected zone (HAZ) of fluorophlogopite glass ceramic are studied. Regression equations between taper, HAZ thickness and laser process parameters are established and the process parameters are optimized. The experimental results show that the laser process parameters are in the order of the current, defocusing amount, pulse width, and repetition number based on their influence degree on taper and HAZ. In addition, the taper and HAZ thickness are also influenced by the interactive effects of the current and defocusing amount, and the current and pulse width. The established regression equation can describe the relationships between the taper, HAZ thickness and laser process parameters. From the regression equation, the optimized laser process parameters are obtained as follows: 150 A of current, 2 ms of pulse width, 3 of repetition number and 2.18 mm of defocusing amount.

Chip breaker with a raised dot was fabricated on the rake face of high speed steel (HSS) turning tool using laser powder cladding method. Based on chip breaking condition and chip breaking dot position conditions, three position equations of laser cladded chip breaking dot were established. The theoretical position regions of laser cladded chip breaking dot on rake face of tool were determined. Turning experiments of aluminum alloy were carried out. Chip breaking processes were observed with high-speed camera. The calculated position regions of chip breaking dot are in good agreement with the experimental results. Turning tool with chip breaking dot located in the position region on rake face has effective chip breaking ability. There also exists a transition position region of chip breaking dot. The position regions could provide reference for the fabrication of laser cladded chip breaking dot on rake face of HSS cutting tools.

应用激光加工技术,在高速钢试件表面制备出条纹织构,对高速钢条纹织构试件进行了销盘式摩擦磨损试验,并测试了磨损量.通过实验,分析织构参数对高速钢激光加工条纹表面磨损量的影响规律.通过对数学模型的拟合分析,确定并建立了高速钢条纹试件表面磨损量的二阶数学模型.根据该磨损量数学模型,对条纹参数进行了优化.研究表明,织构参数对高速钢条纹表面磨损量的影响程度依次为高度、宽度和间距;方差分析表明,所建立的高速钢条纹表面磨损量与织构参数之间的数学模型是显著的.同时确定了激光织构表面低磨损量的条纹参数取值范围,得到了优化后的条纹织构参数.

Purpose The study aims to compare tribological properties between laser dimple textured surface and drilled dimple textured surface, and to analyze the influence of dimple hardened edges and ability of trapping wear debris on wear properties of dimple textured surfaces. Design/methodology/approach Circular textured dimples were produced on AISI 1,045 specimen surfaces using laser surface texturing (LST) and drilled surface texturing (DST) methods. Tribological behaviors of LST, DST and non-textured specimens were studied using ball-on-disc tribo-tester. Metallographic structures, dimples and worn surface morphologies were observed using a three-dimensional digital microscope. Hardnesses of substrate and dimple edges were measured. Findings There was no obvious difference in wear and friction coefficients between LST and DST specimens. Hardnesses of laser dimple edges were much higher than that of drilled dimple edges and specimen substrate. The hardened materials of laser dimple edge included recast zone and heat affect zone. Laser dimple was cone-shaped and drilled dimple was cylinder-shaped. Drilled dimple had a better ability of trapping wear debris than laser dimple. Non-uniform wear phenomenon occurred on worn surfaces of LST dimple specimens. Originality/value The ability of textured dimples to trap wear debris is affected by single dimple volume. Hardened edges of dimples cause non-uniform wear on worn surfaces of LST specimens.

WC/Co cladding tracks on W6MoSCr4V2 high speed steel specimen surface were fabricated with laser cladding technology to improve the tribological properties of high speed steel.The microstructures of specimens were observed by metallurgical microscope,and the hardness was measured by microhardness tester.Moreover,the friction and wear tests were carried out by pin-disk tribometer on the high speed steel and WC/CO cladding layer specimens,and the wear morphology was observed by three-dimensional digital microscope.Results showed that compared with high speed steel substrate,the hardness of WC/Co cladding tracks increased.The wear mechanism of WC/Co cladding tracks was abrasive wear,while the wear mechanism of WC/Co cladding track space area included abrasive wear and adhesive wear.In addition,the hardness improvement,friction reduction and heat dissipation of cladding tracks and the hard & soft alternation between cladding tracks and interval surfaces on specimen surfaces were contributed to the improvement of tribological resistance of WC/Co cladding specimens.

应用脉冲激光在高速钢基体上熔覆Ni基WC条纹,用体视显微镜观察熔覆条纹的裂纹.通过析因实验设计,研究工艺参数对熔覆裂纹缺陷的影响,建立了裂纹率与工艺参数之间的回归方程.研究表明,熔覆工艺参数对裂纹的影响程度依次为电流、脉宽、频率、扫描速度、离焦量,熔覆裂纹的产生还受到工艺参数间交互作用的影响.本文所建立的回归方程能够较好地描述熔覆条纹裂纹率与工艺参数之间的关系.

采用脉冲激光在碳素结构钢试件表面加工出凹坑织构,测试了激光凹坑边缘的硬度,通过销盘磨损实验,分析激光凹坑试件表面的摩擦磨损特性,观察了磨损表面形貌,并与普通试件进行了对比.结果表明:激光加工试件的凹坑边缘硬度提高,磨损量降低.激光加工凹坑表面的磨损机制以磨粒磨损为主.激光凹坑边缘硬质点的支撑和保护作用,以及凹坑的磨屑存储作用,减少了激光凹坑试件的磨粒磨损程度.激光凹坑织构改变了摩擦副之间的接触性能,减少黏着结点的形成概率,可以降低黏着磨损.激光加工凹坑表面具有降低磨粒磨损和黏着磨损的作用,从而提高激光凹坑织构试件表面的耐磨性.

氟金云母玻璃陶瓷材料在切削过程中存在严重的磨损现象.对氟金云母玻璃陶瓷进行了车削加工实验,应用分式析因实验设计研究刀具角度参数对高速钢刀具磨损的影响.通过方差分析,获得刀具角度对刀具磨损的影响显著性及其排序,通过回归分析,建立了刀具磨损量与刀具角度之间的回归方程.研究表明,刀具角度参数对刀具磨损量的影响程度依次为刃倾角,后角,前角,主偏角和副偏角.刀具磨损受到刀具角度间交互作用的影响,其中前角与主偏角、后角和主偏角的交互作用极显著.所建立的回归方程能够较好地描述高速钢刀具磨损量与高速钢刀具角度之间的关系.

Dimple texturing on CuSn6 tin bronze specimen surfaces were fabricated with laser surface texturing (LST) and drilled surface texturing (DST) methods, respectively. Friction coefficients and wear of textured and non textured specimens were measured and compared. Experimental results show that more severe wear of laser textured specimens is observed than that of non-textured specimens. Shrinkages, porosities, cracks and inverse segregation in the heat affected zone will result in material softening of laser dimple edges. Material softening can cause the destruction of oxide film easily, and shorten the duration of mild wear regime of LST specimens. However, the work hardening of drilled dimple edges on bronze surface can increase the duration of mild wear regime and improve wear resistance of DST specimens.