Mechanical Surface Treatments of AISI 304 Stainless Steel: Effects on Surface Microrelief, Residual Stress, and Microstr
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JMEPEG https://doi.org/10.1007/s11665-019-04273-y
Mechanical Surface Treatments of AISI 304 Stainless Steel: Effects on Surface Microrelief, Residual Stress, and Microstructure D.A. Lesyk, H. Soyama, B.N. Mordyuk, V.V. Dzhemelinskyi, S. Martinez, N.I. Khripta, and A. Lamikiz (Submitted January 30, 2019; in revised form July 12, 2019) The surface roughness, residual stress, and microstructure of AISI 304 stainless steel specimens after laser shock peening (LSP), water jet cavitation peening (WjCP), water jet shot peening (WjSP), and multi-pin ultrasonic impact treatment (UIT) were studied in this work. Compared to the initial state, the surface roughness (Ra) was, respectively, decreased by approx. 5.5, 7.8, 38.2, and 91.1% after the LSP, WjCP, WjSP, and UIT processes. The volume fraction of e-martensite of 3-5% was observed in all treated specimens except for the LSP-treated ones. The volume fraction of a¢-martensite was increased in the following sequence: WjCP ( 5%), LSP ( 5%), WjSP ( 25%), UIT ( 50%). The studied mechanical surface treatments promote a significant reduction in grains size of both austenite ( 15-20 nm) and martensite ( 20-37 nm) leading to essential hardening. All studied processes result in the formation of compressive residual stresses (2 377…693 MPa) and the improvement in the bearing curve parameters. The microhardness estimated accounting for the contributions of different hardening mechanisms to the yield strength magnitude correlates well with the experimental data. The grain boundary hardening and dislocation hardening are concluded to be the most influential mechanisms. Keywords
bearing curve parameters, hardening mechanisms, laser shock peening, multi-pin ultrasonic impact treatment, roughness, water jet cavitation peening, water jet shot peening
1. Introduction Improvement in the surface properties of the end-products by changing their surface roughness, grain structure, hardness, and residual stresses is very relevant due to the fact that the destruction of the materials including wear, corrosion, and fatigue failure usually depends on the surface state. It is well known that enhancing the operational properties of the metallic parts is largely provided by the surface plastic deformation methods due to the formation of a specific surface microrelief (Ref 1, 2), fine-grained structure (Ref 3), and comprehensive residual stress (Ref 4) in subsurface layers. Austenitic stainless steels are the most widely used grade of stainless steel in the industry due to its superior resistance to
D.A. Lesyk and V.V. Dzhemelinskyi, Laser Systems and Physical Technologies Department, National Technical University of Ukraine ‘‘Igor Sikorsky Kyiv Polytechnic Institute’’, 37 Peremohy Ave., Kyiv 03056, Ukraine; H. Soyama, Finemechanics Department, Tohoku University, 6-6-01 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan; B.N. Mordyuk and N.I. Khripta, Physical Principles for Surface Engineering Department, G.V. Kurdyumov Institute for Metal Physics of the NAS of Ukraine, 36 Academician Vernadsky Blv
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