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Influence of Ultrafine‐Grained Layer on Gaseous Nitriding of Large‐Sized Titanium Plate
Author(s) -
Yao Quantong,
Sun Jian,
Zhang Guanglan,
Tong Weiping,
Zuo Liang
Publication year - 2018
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201700455
Subject(s) - nitriding , materials science , titanium , scanning electron microscope , layer (electronics) , transmission electron microscopy , metallurgy , severe plastic deformation , surface layer , diffusion , diffusion layer , composite material , grain size , nanotechnology , physics , thermodynamics
In this paper, mechanical shot blasting on a large sized titanium plate is conducted to induce severe plastic deformation, which generates an ultrafine‐grained surface layer. The effect of an ultrafine‐grained layer on nitriding is evaluated at nitriding temperatures from 600 to 850 °C. The structural phases and mechanical property improvements are investigated and compared to those of a coarse‐grained specimen by using X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and mechanical property measurements. The results indicate that an ultrafine‐grained layer enhances the nitriding kinetics and produces a thicker nitrided layer than that of a coarse‐grained plate at the same gaseous nitriding temperatures. The improved kinetics are attributed to a greater number of grain boundaries and defects introduced into the titanium plate surface by the mechanical shot blasting treatment. Meanwhile, the surface and cross‐sectional hardness values improve compared to the coarse‐grained plate due to the thicker nitrided layer resulting from deeper nitrogen diffusion.