Peening Techniques for Surface Modification: Processes, Properties, and Applications

Abstract

Surface modification methods have been applied to metals and alloys to change the surface integrity, obtain superior mechanical properties, and improve service life irrespective of the field of application. In this review paper, current state-of-the-art of peening techniques are demonstrated. More specifically, classical and advanced shot peening (SP), ultrasonic impact peening (UIP), and laser shock peening (LSP) have been discussed. The effect of these techniques on mechanical properties, such as hardness, wear resistance, fatigue life, surface roughness, and corrosion resistance of various metals and alloys, are discussed. This study also reports the comparisons, advantages, challenges, and potential applications of these processes.

Keywords: fatigue life; laser shock peening; microstructure; severe plastic deformation; shot peening; ultrasonic impact peening.

Figure 1

Schematic illustration of different peening techniques and the corresponding plastically deformed top surface of the target material: (a) SP; (b) UIP; (c) LSP. Reproduced with permission from [44]. Copyright Elsevier, 2021.

Figure 2

TEM bright field (BF) and the corresponding dark filed (DF) image from the topmost surface of treated Hastelloy X alloy: (a,b) SP; (c,d) SSP sample. Inset in Figure 2d is the statistical distribution of the grain size. Reproduced with permission from [64]. Copyright Elsevier, 2021.

Figure 3

The illustration of grain refinement mechanism of Mg-8Gd-3Y alloy during SSP. Reproduced with permission from [70]. Copyright Elsevier, 2020.

Figure 4

SEM of cast iron surfaces developed by (a) SP; (b) SSP and (c) RSSP. Reproduced with permission from [71]. Copyright Elsevier, 2014.

Figure 5

Ultrasonic peening equipment. Reproduced with permission from [80]. Copyright Elsevier, 2015.

Figure 6

TEM showing (a) trapezoidal Al₂Cu particle as emission source of dislocations (b) DC and DT in the aluminum matrix. Reproduced with permission from [38]. Copyright Elsevier, 2002.

Figure 7

SEM of SS 304 sheets (a) microcracks in weld toe; (b) after UIP treatment closure of microcracks and modified weld toe curvature. Reproduced with permission from [39]. Copyright Elsevier, 2012.

Figure 8

Comparison of the data at the same depth for (a) the variation of magnetization with martensite ratio; and (b) variation of the coercivity with grain size. Reproduced with permission from [83]. Copyright Elsevier, 2020.

Figure 9

SEM of weld bead of CMT welded 6062 aluminum alloy (a) without UIP; (b) with UIP. Reproduced with permission from [85]. Copyright Elsevier, 2018.

Figure 10

Polarization curves for specimens with different impact intensities. Reproduced with permission from [92]. Copyright Elsevier, 2021.

Figure 11

Cross-sectional morphologies of laser cladded AlCoCrCuFeNi HEA coatings: (a) without UIT; (b) with UIT. Reproduced with permission from [94]. Copyright Elsevier, 2021.

Figure 12

LSP on ANSI 304 SS and variation of (a) nano hardness and elastic moduli (b) residual stress with and without LSP. Reproduced with permission from [27]. Copyright Elsevier, 2011.

Figure 13

Optical micrographs of cross-section of 316L steel subjected to (a) SP; (b) LSP. Reproduced with permission from [115]. Copyright Elsevier, 2000.

Figure 14

TEM on (a) LSP treated; (b) untreated specimen Ti6Al4V alloy. Reproduced with permission from [116]. Copyright Elsevier, 1999.

Figure 15

Surface profile comparisons (a) BM; (b) SP and (c) LSP treated specimen. Reproduced with permission from [117]. Copyright Elsevier, 2012.

Figure 16

Typical TEM images of the LSP’ed SLM specimen. (a) Refined acicular martensite and MTs (b) dislocations and refined acicular martensite. Reproduced with permission from [120]. Copyright Elsevier, 2021.

Figure 17

The experimental system of nanoparticle implantation induced by LSP. Reproduced with permission from [123]. Copyright Elsevier, 2021.

Figure 18

Comparison of WLSP and LSP on AISI 4140 steel (a) stress relaxation at 300 °C; (b) stress relaxation after cyclic loading. Reproduced with permission from [131]. Copyright Elsevier, 2011.

Figure 19

Integrated SLM with LSP (a) Process diagram and (b) laser scanning strategy. Reproduced with permission from [136]. Copyright Elsevier, 2020.

Figure 20

(a) Surface hardness and (b) roughness measurements in fs-LSP processed SS 304 under different conditions. Reproduced with permission from [140]. Copyright Elsevier, 2021.

Figure 21

A schematic illustration of indirect-LSSP process. Reproduced with permission from [146]. Copyright Elsevier, 2018.

Figure 22

OM showing the microstructure of direct-LSSP-patterned AZ31B with laser intensities of: (a) 0; (b) 1.18; (c) 1.47; (d) 1.70; (e) 1.92; and (f) 2.12 GW/cm². Reproduced with permission from [147]. Copyright Elsevier, 2020.

Figure 23

TEM images of dislocations in α-SiC ceramics generated by LSP: (a) weak-beam dark- field and (b) bright-field images of dislocations underneath the surface. Reproduced with permission from [149]. Copyright Elsevier, 2019.