Neutral Molten Salt-Bath Carburizing of Ti6Al4V Alloy with Nanocrystalline Surface Layer at Low Temperature Assisted by Surface Mechanical Attrition Treatment

2017 ◽  
Vol 727 ◽  
pp. 1001-1008 ◽  
Author(s):  
Quan Tong Yao ◽  
Wei Ping Tong ◽  
Meng Yao Li ◽  
Guang Lan Zhang
Keyword(s):  
Surface Layer ◽  
Low Temperature ◽  
Molten Salt ◽  
Salt Bath ◽  
Coarse Grained ◽  
Experimental Result ◽  
Surface Mechanical Attrition Treatment ◽  
Neutral Salt ◽  
Mechanical Attrition ◽  
Molten Salt Bath

Nanocrystalline surface layer about 10~15μm thick was fabricated on the surface of Ti6Al4V sheet by means of the surface mechanical attrition treatment (SMAT). The average grain size was about 10nm and the grain characteristic presented equiaxed morphology. The nanocrystalline surface layer could be perfectly maintained below 550°C in the following thermal stability analysis. Neutral salt mixture was about 21% NaCl, 31% BaCl2 and 48% CaCl2 and additionally 5% Na2CO3 of total was utilized. After carburizing process, a continuous charcoal grey carburized layer was composed of TiC and carbon supersaturated solid solution, the hardening layer was about 10~15μm thick. The hardness of the outermost surface reached 1000HV, which was much higher than its coarse-grained counterpart in the same carburizing condition. The experimental result indicated that the carburizing kinetics was obviously enhanced by nanocrystalline surface layer assistance. Furthermore, the neutral molten salt-bath carburizing was verified that it could be performed in a relatively low temperature of 650°C.

Interface Diffusion in Cu Processed by Means of Surface Mechanical Attrition Treatment

2009 ◽  
Vol 289-292 ◽  
pp. 557-563 ◽  
Author(s):  
Z.B. Wang ◽  
K. Wang ◽  
K. Lu ◽  
Gerhard Wilde ◽  
Sergiy V. Divinski
Keyword(s):  
Grain Size ◽  
Surface Layer ◽  
Subsurface Layer ◽  
Coarse Grained ◽  
Surface Mechanical Attrition Treatment ◽  
Nanostructured Surface ◽  
Radiotracer Technique ◽  
Mechanical Attrition ◽  
The Difference ◽  
Effective Diffusivities

A nanostructured surface layer with a gradient microstructure was produced on a Cu plate by means of the surface mechanical attrition treatment (SMAT). Diffusion of Ni in the nanostructured layer was investigated by the radiotracer technique at temperatures from 383 to 438 K. The measured diffusion profiles consist of two distinct sections with different slopes, the steep one corresponding to the top surface layer with the grain size of 10 to 25 nm and the shallow one corresponding to a subsurface layer with a grain size of 25 to 100 nm. The effective diffusivities derived from both sections are more than 2 orders of magnitudes higher than the grain boundary diffusivities in coarse-grained Cu. The significantly accelerated diffusion rates are expected to be associated with the “non-equilibrium” states of interfaces in the nanostructured surface layer induced by SMAT. The difference between the diffusivities in the top and sub- surface layer might result from the fact that most interfaces developed from twin boundaries in the former while produced by dislocation activities in the latter.

Diffusion of Cr in Nanostructured Fe and Low Carbon Steel Produced by Means of Surface Mechanical Attrition Treatment

2006 ◽  
Vol 249 ◽  
pp. 147-154 ◽  
Author(s):  
Z.B. Wang ◽  
N.R. Tao ◽  
W.P. Tong ◽  
Jian Lu ◽  
K. Lu
Keyword(s):  
Surface Layer ◽  
Carbon Steel ◽  
Steel Plate ◽  
Low Carbon Steel ◽  
Coarse Grained ◽  
Surface Mechanical Attrition Treatment ◽  
Low Carbon ◽  
Triple Junctions ◽  
Exponential Factor ◽  
Mechanical Attrition

By means of surface mechanical attrition treatment (SMAT), nanostructured (NS) surface layers were fabricated on a pure iron plate and a low carbon steel plate. Cr diffusion behaviors in the NS Fe phase and the SMAT low carbon steel were investigated. Experimental results showed the activation energy of Cr diffusion in the NS Fe is comparable to that of the GB diffusion, but the pre-exponential factor is much higher. A much thicker Cr-diffusion surface layer was obtained in the SMAT low carbon steel plate than in the coarse-grained one after the same chromizing treatment. The much enhanced diffusivities of Cr in the SMAT samples can be attributed to numerous GBs and triple junctions with a high excess stored energy in the NS surface layer.

Assessment of wear properties on low temperature molten salt bath nitriding on austenitic stainless steel

2020 ◽  
Vol 27 ◽  
pp. 1541-1544
Author(s):  
B. Chaitanya kumar ◽  
P. Sri Charan ◽  
Kanishkar Jayakumar ◽  
D. Alankrutha ◽  
G. Sindhu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Low Temperature ◽  
Molten Salt ◽  
Salt Bath ◽  
Wear Properties ◽  
Salt Bath Nitriding ◽  
Molten Salt Bath

Enhanced Saturation Magnetization of Nanocrystalline Cobalt Produced by Surface Mechanical Attrition Treatment

2011 ◽  
Vol 686 ◽  
pp. 733-739 ◽  
Author(s):  
Wei Li ◽  
Ping Liu ◽  
Feng Cang Ma ◽  
Xin Kuan Liu ◽  
Xiao Hong Chen ◽  
...  
Keyword(s):  
Surface Layer ◽  
Saturation Magnetization ◽  
Hardened Steel ◽  
Coarse Grained ◽  
Surface Mechanical Attrition Treatment ◽  
Diffusion Phenomenon ◽  
Mechanical Attrition ◽  
Steel Balls

A nanocrystalline surface layer is produced in Co plate by surface mechanical attrition treatment (SMAT). The characterization of microstructure and composition indicates that elements of Fe, Cr diffuse from hardened steel balls into the surface layer during SMAT. The diffusion phenomenon results in the composition deviation in the surface layer, leading to higher value of saturation magnetization(Ms) for nanocrystalline Co surface layer in comparison with its coarse-grained counterpart.

Surface Nanocrystallines of Fe3Al Produced by Surface Mechanical Attrition

2011 ◽  
Vol 320 ◽  
pp. 325-328 ◽  
Author(s):  
Jiang Wei Ren ◽  
Dong Li ◽  
Pei Quan Xu
Keyword(s):  
Grain Size ◽  
Surface Layer ◽  
Surface Mechanical Attrition Treatment ◽  
Electronic Microscopy ◽  
X Ray ◽  
Structure And Morphology ◽  
Mechanical Attrition ◽  
Deformed Layer ◽  
Fe3al Intermetallic ◽  
Morphology Of Surface

A nanocrystallines surface layer was produced in Fe3Al intermetallic compound by surface mechanical attrition treatment (SMAT). The microstructure of deformed layer, phase structure and morphology of surface nanocrystallines were characterized through optical microscopy, X-ray diffractometry, transmission electronic microscopy and high resolution electronic microscopy. The results show that a deformed layer about 11μm wide is produced after 10min surface mechanical attrition. The grains on the top surface of Fe3Al are refined to nanocrystallines and the grain size of nanocrystallines is about 35nm. High density dislocations collect on the boundaries of grains. The formation of nanocrystallines is controlled by grain subdivision mechanism.

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