Wheel Life and Cutting-Edge Wear in Mirror-Grinding Using a Coarse-Grained cBN Wheel Treated by Microdressing

2016 ◽  
Vol 10 (5) ◽  
pp. 753-758 ◽  
Author(s):  
Yoshio Ichida ◽  

This paper presents the wheel life and wear behavior of the cutting edges of a coarse-grained, microdressed cubic boron nitride (cBN) wheel used in mirror-grinding of hardened roll-steel. Many grain-cutting edges with smooth, ductile-mode cut surfaces and numerous brittle-mode-fractured micro dents are formed on the wheel’s working surface after microdressing with a fine-grained diamond dresser. Cylindrical mirror-grinding experiments are conducted using a metal-bonded cBN wheel with a mesh size of #140 (Average grain sizeda=105 μm). A mirror surface with a roughness below 0.2 μmRzcan be efficiently formed with the wheel surface treated by the abovementioned microdressing method. This wheel surface can perform mirror-grinding with precision for more than nine hours. A flat plane formed via attritious wear of the cutting edge gradually extends with increasing accumulated stock removal, and simultaneously, the unevenness due to wear streaks on this flat plane increases. This increase in the unevenness of the worn flat plane is the main factor causing an increase in the roughness of the mirror surface.

2013 ◽  
Vol 829 ◽  
pp. 177-181 ◽  
Author(s):  
Reyhane Nafar Dehsorkhi ◽  
Soheil Sabooni ◽  
Fathallah Karimzadeh ◽  
Ahmad Rezaeian ◽  
Mohammad Hossein Enayati

An ultrafine grained 304L stainless steel with average grain size of 650±100 nm was produced by a combination of cold rolling and annealing. Wear behavior of the steel was examined by dry sliding wear tests under different loads. Different microstructural characterizations were conducted on the ultrafine grained structure after thermomechanical processing and wear tests. The results demonstrated that the steel had yield strength of 720 MPa and total elongation of 47%, which is almost twice higher than typical coarse grained strength. Also, wear tests results showed a good linear relation between the cumulative wear loss and distance in each normal load. Wear rate was about 0.024, 0.043 and 0.093 mg/m for normal loads of 10, 20 and 30N, respectively. Wear mechanism was also recognized as delamination (in the early stage) and mixture of delamination and abrasion in higher distances.


2005 ◽  
Vol 475-479 ◽  
pp. 401-404 ◽  
Author(s):  
Yong Suk Kim ◽  
J.S. Ha ◽  
Dong Hyuk Shin

Coarse grains of commercial 5052 Al and 5083 Al alloys were refined by the accumulative roll bonding (ARB) process. Average grain size of the refined microstructure was 200 nm. The 5083 Al alloy that has higher Mg content required more deformation for the refinement. Dry sliding wear behavior of the ultra-fine grained (UFG) Al alloys was investigated using a pin-on-disk wear tester at room temperature. The UFG microstructure of the processed alloys hardly increased the wear resistance of the Al alloys in spite of the increased strength and hardness. Wear rate of the UFG Al alloys was higher than that of the non processed coarse-grained starting alloys. The SEM observation of worn surfaces revealed that surface deformation controlled the wear. The low wear resistance of the UFG Al alloys was attributed to non-equilibrium and unstable grain boundaries and low strain hardening capability of the alloys.


2021 ◽  
Vol 5 (3) ◽  
pp. 77
Author(s):  
Berend Denkena ◽  
Alexander Krödel-Worbes ◽  
Sascha Beblein ◽  
Markus Hein

One of the decisive factors for the performance of milling tools is the quality of the cutting edge. The latter results from the process control of the individual steps along the tool manufacturing process chain, which generally includes the sintering or pressing of the blanks, grinding, cutting edge preparation, and coating of the tools. However, the targeted and application-specific design of the process steps in terms of high economic efficiency is currently limited by a lack of knowledge regarding the influence of the corresponding process parameters on the resulting cutting edge quality. In addition, there is a lack of suitable parameters that adequately represent the characteristics of the cutting edge microtopography. This publication therefore investigates the influence of manufacturing processes on cutting edge quality and wear behavior of end mills. On this basis, different characterization parameters for the cutting edge quality are derived and evaluated with regard to their ability to predict the wear behavior.


2021 ◽  
Vol 111 (11-12) ◽  
pp. 833-839
Author(s):  
Kolb Moritz ◽  
Tim Mayer ◽  
Nico Rasenberger

Dieser Beitrag beschreibt, wie sich die Standzeit von Kreissägeblättern durch Schneidkantenpräparation gezielt beeinflussen lässt. Hierfür wurden zunächst einzelne Segmente aus einem Sägeblatt herausgetrennt und Einzahnproben mit variierenden Schneidenmikrogeometrien mittels Bürstspanen präpariert. Anschließend wurde das Einsatz- und Verschleißverhalten der zuvor hergestellten Proben in einem Kreissäge-Modellversuch untersucht.   This article describes how the service life of circular saw blades can be specifically influenced by cutting edge preparation. For this purpose, individual segments were first cut out of a saw blade. These single-tooth specimens with varying cutting edge microgeometries were prepared by abrasive brushing. Then the usage and wear behavior of the previously produced samples was investigated in a circular saw model test.


Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 794 ◽  
Author(s):  
Osman El Atwani ◽  
Kaan Unal ◽  
William Streit Cunningham ◽  
Saryu Fensin ◽  
Jonathan Hinks ◽  
...  

The use of ultrafine and nanocrystalline materials is a proposed pathway to mitigate irradiation damage in nuclear fusion components. Here, we examine the radiation tolerance of helium bubble formation in 85 nm (average grain size) nanocrystalline-equiaxed-grained tungsten and an ultrafine tungsten-TiC alloy under extreme low energy helium implantation at 1223 K via in-situ transmission electron microscope (TEM). Helium bubble damage evolution in terms of number density, size, and total volume contribution to grain matrices has been determined as a function of He+ implantation fluence. The outputs were compared to previously published results on severe plastically deformed (SPD) tungsten implanted under the same conditions. Large helium bubbles were formed on the grain boundaries and helium bubble damage evolution profiles are shown to differ among the different materials with less overall damage in the nanocrystalline tungsten. Compared to previous works, the results in this work indicate that the nanocrystalline tungsten should possess a fuzz formation threshold more than one order of magnitude higher than coarse-grained tungsten.


Author(s):  
Ahmad Omar Mostafa

Grain refinement, by adding master alloys, is an important industrial process for aluminum casting operations. In this work, microstructure, microhardness, tensile properties, surface roughness and wear behavior of Al and both Al-0.15Ti and Al-0.05Ti-0.01B microalloys were investigated. The addition of Ti and B to pure Al reduced the grain size by 83%. The grain refinement effect was due to the presence of Al3Ti and TiB2 particles, which activated the columnar-to-equiaxed transition and improved both microhardness and tensile properties. The presence of both Al3Ti and TiB2 particles was confirmed using thermodynamic calculations. Average microhardness values increased form 39 HV for pure Al to 95 and 76 HV for Al-Ti and Al-Ti-B microalloys, respectively, by solid solution hardening. The enhanced wear behaviour of Al was due to the coarse-grained structure where the plastic deformation mechanism took place. Whereas, grain pull-out dominated the wear behavior of fine-grained specimens. It was concluded that the material with a smooth surface has high friction coefficient and low wear rate.


Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 917 ◽  
Author(s):  
Jiang Liu ◽  
Junbiao Liu ◽  
Xuehui Zhang ◽  
Tahir Ahmad ◽  
Tongxiang Liang ◽  
...  

The nanograins (NG) on the top surface layer of alloy 690 were successfully prepared by ultrasonic surface rolling treatment (USRT). The average grain size of NG alloy 690 was 55 nm, and the thickness of the NG surface layer was about 1 μm. Meanwhile, the surface roughness was significantly reduced after surface nanocrystalliztion. The corrosion behavior of alloy 690 before and after USRT was studied in a secondary side environment containing chloride. Electrochemical corrosion experiments demonstrated that the passive film generated by USRT was denser than that formed on coarse-grained (CG) alloy 690. Pitting corrosion was prone to occur in grain boundaries of CG alloy 690, and the pits on the surface of NG alloy 690 were smaller than those generated on CG alloy 690 after 1000 h of an immersion experiment.


Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 911
Author(s):  
Qiang Wu ◽  
Tao Qin ◽  
Mingxue Shen ◽  
Kangjie Rong ◽  
Guangyao Xiong ◽  
...  

The influence of surface gas nitriding on wheel/rail rolling contact fatigue and wear behavior of CL60 wheel was studied on a new rolling contact fatigue/wear tester (JD-DRCF/M). The failure mechanisms of the wheel/rail surface after the gas nitriding and without gas nitriding on the wheel surface were compared and analyzed. The results show that the wheel with gas nitriding could form a dense and hard white bright layer which was approximately 25 μm thick and a diffusion layer which was approximately 70 μm thick on the wheel surface. Thus, the gas nitriding on the railway wheel not only significantly improved the wear resistance on the surface of the wheel, but also effectively reduced the wear of the rail; the results show that the material loss reduced by 58.05% and 10.77%, respectively. After the wheel surface was subjected to gas nitriding, the adhesive coefficient between the wheel/rail was reduced by 11.7% in dry conditions, and was reduced by 18.4% in water media, but even so, the wheel with gas nitriding still could keep a satisfactory adhesive coefficient between the wheel/rail systems, which can prevent the occurrence of phenomena such as wheel-slip. In short, the gas nitriding on the wheel surface can effectively reduce the wear, and improve the rolling contact fatigue resistance of the wheel/rail system. This study enlarges the application field of gas nitriding and provides a new method for the surface protection of railway wheels in heavy-duty transportation.


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