1 College of Materials and Metallurgy, Guizhou University, Guiyang 550025, China 2 School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
The surface of 20CrMnTi steel was strengthened by the square-spot laser shock peening(LSP) with 25J and 30J pulse energy. The layered style morphology, roughness, micro-hardness and residual compressive stress of the strengthened sample surface by LSP were test. The polarization curve and the corrosion morphology were investigated. The results show that, plastic deformation occurs in the surface after square-spot LSP, the surface roughness Ra of the specimens reduces to 0.433μm, and micro-hardness improves, great residual compressive stress is formed. The appropriate laser power density of LSP increases the density of the strengthened layer and passive film on the surface, and the transverse residual compressive stress makes the passive film more stable, and improves the corrosion resistance of materials. But the too large laser power density will cause the generation of pit defects in the material surface and the ablation of Al foil. Thus the Cl- is accumulated at the pit defects, the local tensile stress is generate on the surface of the material, and the surface passive film on the material is destroyed, and degrade the performance of corrosion resistance of the material.
WANG C J , TANG C M , WANG G C , et al. Experimental study of femtosecond laser-introduced generation of high energy ions[J]. Journal of Optoelectronics·Laser, 2013, (2): 403- 407.
2
FAIRAND B P , CLAUER A H , JUNG R G , et al. Quantitative assessment of laser-induced stress waves generated at confined surfaces[J]. Applied Physics Letters, 1974, 25 (8): 431- 433.
doi: 10.1063/1.1655536
3
IGNAT S , SALLAMAND P , GREVEY D , et al. Magnesium alloys laser (Nd:YAG) cladding and alloying with side injection of aluminium powder[J]. Applied Surface Science, 2004, 225 (1/4): 124- 134.
WANG X , LI X D , SONG Y G , et al. Effect of shot peening on fatigue limit stress concentration sensitivity of 3 kinds of typical materials for aeroengine[J]. Journal of Aeronautical Materials, 2017, 37 (6): 102- 107.
doi: 10.11868/j.issn.1005-5053.2017.000097
6
GOLDEN P J , HUTSON A , SUNDARAM V , et al. Effect of surface treatments on fretting fatigue of Ti-6Al-4V[J]. International Journal of Fatigue, 2007, 29 (7): 1302- 1310.
doi: 10.1016/j.ijfatigue.2006.10.005
CAO Z W , ZOU S K , LIU F J , et al. Laser shock processing on 1Cr11Ni2W2MoV martensite steel[J]. Chinese Journal of Lasers, 2008, 35 (2): 316- 320.
8
LIU K K , HILL M R . The effects of laser peening and shot peening on fretting fatigue in Ti-6Al-4V coupons[J]. Tribology International, 2009, 42 (9): 1250- 1262.
doi: 10.1016/j.triboint.2009.04.005
9
HAMMERSLEY G , HACKEL L A , HARRIS F . Surface prestressing to improve fatigue strength of components by laser shot peening[J]. Optics & Lasers in Engineering, 2000, 34 (Suppl 4/6): 327- 337.
ZOU S K , CAO Z W , YANG H L . Natural frequency test of turbine blades in laser shock processing[J]. China Mechanical Engineering, 2010, (6): 648- 651.
BI F Q , ZHANG C C , LI H C , et al. Development and application of laser shock processing[J]. Ordnance Material Science and Engineering, 2010, 33 (1): 101- 104.
12
MASSE J E , BARREAU G . Laser generation of stress waves in metal[J]. Surface & Coatings Technology, 1995, 70 (2): 231- 234.
13
CAO Z W , XU H Y , ZOU S K , et al. Investigation of surface integrity on TC17 titanium alloy treated by square-spot laser shock peening[J]. Chinese Journal of Aeronautics, 2012, 25 (4): 650- 656.
doi: 10.1016/S1000-9361(11)60429-9
CHEN J F , LI X C , ZHOU J Y , et al. Research on corrosion resistance and mechanism of strengthened layer on AM50 Mg alloy surface processed by laser shot peening[J]. Chinese Journal of Lasers, 2011, 38 (12): 53- 58.
15
周南, 乔登江. 脉冲束辐照材料动力学[M]. 北京: 国防工业出版社, 2002.
15
ZHOU N , QIAO D J . Material dynamics under pulse beam radiation[M]. Beijing: National Defense Industry Press, 2002.
16
PEYRE P , FABBRO R , MERRIEN P , et al. Laser shock processing of aluminium alloys. application to high cycle fatigue behaviour[J]. Materials Science and Engineering:A, 1996, 210 (1/2): 102- 113.
17
FABBRO R , FOURNIER J , BALLARD P , et al. Physical study of laser-produced plasma in confined geometry[J]. Journal of Applied Physics, 1990, 68 (2): 775- 784.
doi: 10.1063/1.346783
GE M Z , ZHANG Y K , XIANG J Y . Research on laser shock strengthening and stress corrosion cracking resistance of AZ31B magnesium alloy[J]. Chinese Journal of Lasers, 2010, 37 (11): 2925- 2930.
19
MAAWAD E , SANO Y , WAGNER L , et al. Investigation of laser shock peening effects on residual stress state and fatigue performance of titanium alloys[J]. Materials Science and Engineering:A, 2012, 536 (1): 82- 91.
HUA Y Q , CHEN R F , LU M , et al. Study on the experiment of 40Cr steel by laser shock processing[J]. Chinese Journal of Lasers, 2004, 31 (4): 495- 498.
21
CHU J P , RIGSBEE J M , BANAŚ G , et al. Laser-shock processing effects on surface microstructure and mechanical properties of low carbon steel[J]. Materials Science and Engineering:A, 1999, 260 (1/2): 260- 268.
22
HU Y X , YAO Z Q . Overlapping rate effect on laser shock processing of 1045 steel by small spots with Nd:YAG pulsed laser[J]. Surface & Coatings Technology, 2008, 202 (8): 1517- 1525.
23
PEYRE P , BERTHE L , FABBRO R . Improving the properties of materials with laser-peening:an overview on french activities[J]. American Society of Mechanical Engineers Pressure Vessels & Piping Division PVP, 2006, (10): 185- 192.
LUO X K , WANG Q , TANG Z H , et al. Effect of laser shock peening on surface integrity and fatigue property of Ti-6Al-4V alloy[J]. Titanium Industry Progress, 2016, 33 (2): 33- 37.
LI W , LI Y H , WANG C , et al. Effects of stress state and microstructure change on metallic fatigue performance under laser shock processing[J]. Aviation Precision Manufacturing Technology, 2009, 45 (3): 37- 39.
LIU T Q , LI C Z , SHENG W , et al. Microstructure of surface layer of 40CrNi2Si2MoVA steel after shot-peening[J]. Journal of Aeronautical Materials, 2016, 36 (2): 28- 32.
LI S Z , ZHANG L F , XING Q P . Effect of laser shock processing on electrochemical corrosion behavior of AZ91 magnesium alloy[J]. Chinese Journal of Lasers, 2013, (5): 74- 78.
CUI Z F , HAN Y C , ZHUANG L J , et al. Corrosion behavior and mechanisms of metals in Cl- environment[J]. Petrochemical Corrosion and Protection, 2011, 28 (4): 1- 5.
DIAO Z Y , HAN Y Y , LI H X . Corrosion study of iron in acid and alkali and Cl- media[J]. Journal of Shandong Normal University(Natural Science), 2000, 15 (3): 274- 278.
DONG Y Z , ZHOU X D , SHEN T S , et al. Progress of study on corrosion and protection of materials for ship equipments in marine environment[J]. Corrosion Science and Protection Technology, 2004, 16 (1): 29- 32.
32
CAO Z W , ZOU S K , CHE Z G , et al. Surface defects produced by laser shock peening with aluminium foil ablative layer[J]. Rare Metal Materials and Engineering, 2013, 42 (Suppl 2): 217- 221.