Title: Influence of hydrogen on surface integrity and phase transformation of laser peened 316L stainless steel

Authors: Jianzhong Zhou; Yang Zheng; Shu Huang; Jie Sheng; Wensheng Tan

Addresses: School of Mechanical Engineering, Jiangsu University, 212013 Zhenjiang, China ' School of Mechanical Engineering, Jiangsu University, 212013 Zhenjiang, China ' School of Mechanical Engineering, Jiangsu University, 212013 Zhenjiang, China ' School of Mechanical Engineering, Jiangsu University, 212013 Zhenjiang, China ' Changzhou Key Laboratory of Large Plastic Parts Intelligence Manufacturing, Changzhou College of Information Technology, 213164 Changzhou, China

Abstract: To investigate the influence of hydrogen atoms on the surface integrity and the phase transformation of type 316L stainless steel after laser peening, specimens of laser peened 316L austenitic stainless steel were cathodic hydrogen charged. The surface residual stress of samples subjected to laser peening, the metallurgical structures and the microhardness were studied. The result shows that compressive residual stress is induced by laser peening. The compressive residual stress is 35.55 MPa, 46 MPa and 72 MPa, respectively, when the laser energy is 2 J, 5 J and 8 J. Meanwhile, laser peening refines the grain size, and the surface microhardness reveals that laser peening suppress the increase of microhardness caused by hydrogen atoms. Compared with unimpacted specimens, the amount of hydrogen attacked holes on impacted samples is decreased. The X-ray diffraction reveals that hydrogen charging is responsible for the martensite formed on the surface and the laser peening suppress the formation of martensite.

Keywords: laser peening; 316L stainless steel; hydrogen embrittlement; surface residual stress; surface integrity; metallographic structure; surface microhardness; phase transformation; nanotechnology.

DOI: 10.1504/IJNM.2017.085115

International Journal of Nanomanufacturing, 2017 Vol.13 No.3, pp.257 - 269

Received: 01 Dec 2015
Accepted: 21 Apr 2016
Published online: 12 Jul 2017 *

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