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Volume 2017 (2017), Article ID 2189614, 4 pages
https://doi.org/10.1155/2017/2189614
Research Article

Characterization of Surface Modification of 347 Stainless Steel upon Shot Peening

1School of Metallurgy and Materials Engineering, Chongqing University of Science & Technology, Chongqing 401331, China
2The Center of Material Analysis and Testing, Chongqing University of Science & Technology, Chongqing 401331, China
3School of Nano & Advanced Materials Engineering, Changwon National University, Changwon 51140, Republic of Korea

Correspondence should be addressed to Kejian Li; moc.liamg@nnaijekil

Received 24 July 2017; Revised 8 October 2017; Accepted 24 October 2017; Published 12 December 2017

Academic Editor: Guosong Wu

Copyright © 2017 Kejian Li et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Plastic deformations, such as those obtained by shot peening on specimen surface, are an efficient way to improve the mechanical behavior of metals. Generally, scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) are commonly used to observe the complex microstructural evolutions, such as grain refinement and phase transformation, induced by the surface treatment. In this work, the microstructure of 347 stainless steel, after ultrasonic shot peening (USP) treatments, was investigated. SEM, EBSD, transmission electron microscopy, and X-ray diffraction were used to observe the microstructural evolutions, such as grain refinement and phase transformation. Deformation depth after the USP treatment was about 200 μm. Grain size on the treated surface layer was about 100 nm, with two phases: austenite and α′-martensite. The percentages of the austenite and α′-martensite phases were 54% and 46%, respectively, which constitute an exact expression of the degree of plastic deformation on austenitic stainless steel.