The Experts below are selected from a list of 2277 Experts worldwide ranked by ideXlab platform
Shu Huang - One of the best experts on this subject based on the ideXlab platform.
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Enhancement of fatigue properties of 2024-T351 aluminum alloy processed by cryogenic Laser Peening
Vacuum, 2019Co-Authors: Li Jing, Jianzhong Zhou, Chen Huan, Yunjie Sun, Xuliang Tian, Yu Huang, Aixin Feng, Shu HuangAbstract:Abstract The tensile fatigue performance of 2024-T351 aluminum alloy processed by room temperature Laser Peening (RT-LP) and cryogenic Laser Peening (CLP) were explored. The nanoindentation measurement was performed. Scanning electron microscopic and transmission electron microscopic were used to inspect the microstructure evolution. Experimental results indicated that tensile fatigue life of the specimen subjected to CLP increased by 6.8% when compared with the RT-LP specimen. Additionally, CLP could induce finer grain and higher-density of dislocation structure, which have an important contribution to improving the nano-hardness and tensile fatigue properties of 2024-T351 aluminum alloy.
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Investigation on mechanical properties and microstructural evolution of TC6 titanium alloy subjected to Laser Peening at cryogenic temperature
Materials Science and Engineering: A, 2018Co-Authors: Li Jing, Meng Xiankai, Jianzhong Zhou, Shu Huang, Feng Aixin, Sun Yunhui, Yunjie Sun, Xuliang Tian, Yu HuangAbstract:Abstract The aim of this study was to investigate the influence of the synergistic function of cryogenic temperature and ultrahigh strain rate deformation during the process of Cryogenic Laser Peening (CLP) on the mechanical properties and microstructural evolution of TC6 titanium alloy. The measurements of tensile properties at room and elevated temperatures, as well as micro-hardness on the cross-sectional direction were carried out. Meanwhile, the microstructural evolution was characterizated by Electron Backscattered Diffraction (EBSD) analysis and Transmission Electron Microscopy (TEM) observation. The experimental results demonstrated that cryogenic Laser Peening could significantly improve the strength and ductility, as well as the stability at elevated temperature condition of TC6 titanium alloy. At the same time, cryogenic Laser Peening could provide higher surface micro-hardness than room temperature Laser Peening (RT-LP), the surface micro-hardness of the specimen subjected to cryogenic Laser Peening increased by 4.86% than that of the specimen treated by room temperature Laser Peening. Additionally, cryogenic Laser Peening could generate finer grains and higher-density of dislocation structures, while large numbers of sub-grains and mechanical twins were also observed in the surface layer. Finally, the microscopic strengthening mechanism of cryogenic Laser Peening for better mechanical properties on TC6 titanium alloy was also analyzed in detail.
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Analysis of microstructure and tensile properties produced by cryogenic Laser Peening on 2024-T351 aluminum alloy
Vacuum, 2018Co-Authors: Li Jing, Jianzhong Zhou, Shu Huang, Feng Aixin, Yunjie Sun, Xuliang Tian, Yu Huang, Meng XiankaiAbstract:Abstract The microstructural response and tensile properties on 2024-T351 aluminum alloy specimens induced by cryogenic Laser Peening were investigated. The microstructure behaviors were characterized by transmission electron microscopic examination and electron backscattered diffraction analysis. Tensile properties tests at room temperature were also performed. The experimental results cleared that compared with room temperature Laser Peening, cryogenic Laser Peening can induce higher-density of dislocation and smaller-size grain, while the strength and plasticity of the processed 2024-T351 aluminum alloy were simultaneously increased. The analysis results suggested that the more excellent tensile properties were attributed to the more beneficial microstructural evolution induced by cryogenic Laser Peening.
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Residual stress relaxation and its effects on the fatigue properties of Ti6Al4V alloy strengthened by warm Laser Peening
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2017Co-Authors: Meng Xiankai, Jianzhong Zhou, Su Chun, Shu Huang, Kaiyu Luo, Jie Sheng, Wensheng TanAbstract:Abstract A method combining experiment and simulation was used in this paper to study the effects of warm Laser Peening (WLP) on the residual stress relaxation (RSR) in Ti6Al4V titanium alloy. Moreover, the effects of RSR on fatigue properties and its mechanism were both revealed. Laser Peening experiments were conducted at room temperature (RT-LP) and elevated temperature (300 °C-WLP). Then the yield strengths of specimens were obtained through tensile experiments and their improvement induced by WLP was analyzed by microstructures. A finite element analysis was used to research the effects of RT-LP and 300 °C-WLP on the RSR during fatigue. Finally, the fatigue life and fracture microstructures were both measured and analyzed. The results indicate that the severe plastic strain induced by 300 °C-WLP results in lots of crossed acicular α phases with a short spacing, which promotes the interactions between α phases and leads to an increasing dislocation density. Therefore, the yield strength of 300 °C-WLPed specimens is much greater than RT-LPed samples based on the Hall-Petch relations. Besides, the simulated results show that the extended yield strength of 300 °C-WLPed specimens significantly decreases the d σ /d e during fatigue and thus reduces the relaxation of CRS. Moreover, it can be found that the fatigue life of 300 °C-WLPed specimens is subjected to an significant increase, which can be attributed to the increasing finished crack lengths and the decreasing RSR.
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effects of Laser Peening on residual stresses and fatigue crack growth properties of ti 6al 4v titanium alloy
Optics and Lasers in Engineering, 2014Co-Authors: Jianzhong Zhou, Shu Huang, Jie Sheng, L D Zuo, Xiankai Meng, Q Tian, Y H Han, Weili ZhuAbstract:Abstract The effects of Laser Peening (LP) with different Laser Peening coverage rates on residual stresses and fatigue crack growth (FCG) properties of Ti–6Al–4V titanium alloy were investigated. Residual stresses after LP and micro-structure with different fatigue striation patterns on fracture cross-sections were analyzed. Compressive residual stresses and dense dislocation arrangements can be obtained in the superficial layer after LP. The influence of compressive residual stresses induced under different LP coverage rates on FCG properties was revealed. LP coverage rate had an apparent influence on FCG properties as confirmed by the fatigue striation spacing on fracture cross-sections. Moreover, FCG rate decreased with the increase of compressive residual stresses perpendicular to the crack growth direction, which indicated that LP had an obvious inhibitory effects on FCG.
Jianzhong Zhou - One of the best experts on this subject based on the ideXlab platform.
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Enhancement of fatigue properties of 2024-T351 aluminum alloy processed by cryogenic Laser Peening
Vacuum, 2019Co-Authors: Li Jing, Jianzhong Zhou, Chen Huan, Yunjie Sun, Xuliang Tian, Yu Huang, Aixin Feng, Shu HuangAbstract:Abstract The tensile fatigue performance of 2024-T351 aluminum alloy processed by room temperature Laser Peening (RT-LP) and cryogenic Laser Peening (CLP) were explored. The nanoindentation measurement was performed. Scanning electron microscopic and transmission electron microscopic were used to inspect the microstructure evolution. Experimental results indicated that tensile fatigue life of the specimen subjected to CLP increased by 6.8% when compared with the RT-LP specimen. Additionally, CLP could induce finer grain and higher-density of dislocation structure, which have an important contribution to improving the nano-hardness and tensile fatigue properties of 2024-T351 aluminum alloy.
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Investigation on mechanical properties and microstructural evolution of TC6 titanium alloy subjected to Laser Peening at cryogenic temperature
Materials Science and Engineering: A, 2018Co-Authors: Li Jing, Meng Xiankai, Jianzhong Zhou, Shu Huang, Feng Aixin, Sun Yunhui, Yunjie Sun, Xuliang Tian, Yu HuangAbstract:Abstract The aim of this study was to investigate the influence of the synergistic function of cryogenic temperature and ultrahigh strain rate deformation during the process of Cryogenic Laser Peening (CLP) on the mechanical properties and microstructural evolution of TC6 titanium alloy. The measurements of tensile properties at room and elevated temperatures, as well as micro-hardness on the cross-sectional direction were carried out. Meanwhile, the microstructural evolution was characterizated by Electron Backscattered Diffraction (EBSD) analysis and Transmission Electron Microscopy (TEM) observation. The experimental results demonstrated that cryogenic Laser Peening could significantly improve the strength and ductility, as well as the stability at elevated temperature condition of TC6 titanium alloy. At the same time, cryogenic Laser Peening could provide higher surface micro-hardness than room temperature Laser Peening (RT-LP), the surface micro-hardness of the specimen subjected to cryogenic Laser Peening increased by 4.86% than that of the specimen treated by room temperature Laser Peening. Additionally, cryogenic Laser Peening could generate finer grains and higher-density of dislocation structures, while large numbers of sub-grains and mechanical twins were also observed in the surface layer. Finally, the microscopic strengthening mechanism of cryogenic Laser Peening for better mechanical properties on TC6 titanium alloy was also analyzed in detail.
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Analysis of microstructure and tensile properties produced by cryogenic Laser Peening on 2024-T351 aluminum alloy
Vacuum, 2018Co-Authors: Li Jing, Jianzhong Zhou, Shu Huang, Feng Aixin, Yunjie Sun, Xuliang Tian, Yu Huang, Meng XiankaiAbstract:Abstract The microstructural response and tensile properties on 2024-T351 aluminum alloy specimens induced by cryogenic Laser Peening were investigated. The microstructure behaviors were characterized by transmission electron microscopic examination and electron backscattered diffraction analysis. Tensile properties tests at room temperature were also performed. The experimental results cleared that compared with room temperature Laser Peening, cryogenic Laser Peening can induce higher-density of dislocation and smaller-size grain, while the strength and plasticity of the processed 2024-T351 aluminum alloy were simultaneously increased. The analysis results suggested that the more excellent tensile properties were attributed to the more beneficial microstructural evolution induced by cryogenic Laser Peening.
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Residual stress relaxation and its effects on the fatigue properties of Ti6Al4V alloy strengthened by warm Laser Peening
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2017Co-Authors: Meng Xiankai, Jianzhong Zhou, Su Chun, Shu Huang, Kaiyu Luo, Jie Sheng, Wensheng TanAbstract:Abstract A method combining experiment and simulation was used in this paper to study the effects of warm Laser Peening (WLP) on the residual stress relaxation (RSR) in Ti6Al4V titanium alloy. Moreover, the effects of RSR on fatigue properties and its mechanism were both revealed. Laser Peening experiments were conducted at room temperature (RT-LP) and elevated temperature (300 °C-WLP). Then the yield strengths of specimens were obtained through tensile experiments and their improvement induced by WLP was analyzed by microstructures. A finite element analysis was used to research the effects of RT-LP and 300 °C-WLP on the RSR during fatigue. Finally, the fatigue life and fracture microstructures were both measured and analyzed. The results indicate that the severe plastic strain induced by 300 °C-WLP results in lots of crossed acicular α phases with a short spacing, which promotes the interactions between α phases and leads to an increasing dislocation density. Therefore, the yield strength of 300 °C-WLPed specimens is much greater than RT-LPed samples based on the Hall-Petch relations. Besides, the simulated results show that the extended yield strength of 300 °C-WLPed specimens significantly decreases the d σ /d e during fatigue and thus reduces the relaxation of CRS. Moreover, it can be found that the fatigue life of 300 °C-WLPed specimens is subjected to an significant increase, which can be attributed to the increasing finished crack lengths and the decreasing RSR.
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effects of Laser Peening on residual stresses and fatigue crack growth properties of ti 6al 4v titanium alloy
Optics and Lasers in Engineering, 2014Co-Authors: Jianzhong Zhou, Shu Huang, Jie Sheng, L D Zuo, Xiankai Meng, Q Tian, Y H Han, Weili ZhuAbstract:Abstract The effects of Laser Peening (LP) with different Laser Peening coverage rates on residual stresses and fatigue crack growth (FCG) properties of Ti–6Al–4V titanium alloy were investigated. Residual stresses after LP and micro-structure with different fatigue striation patterns on fracture cross-sections were analyzed. Compressive residual stresses and dense dislocation arrangements can be obtained in the superficial layer after LP. The influence of compressive residual stresses induced under different LP coverage rates on FCG properties was revealed. LP coverage rate had an apparent influence on FCG properties as confirmed by the fatigue striation spacing on fracture cross-sections. Moreover, FCG rate decreased with the increase of compressive residual stresses perpendicular to the crack growth direction, which indicated that LP had an obvious inhibitory effects on FCG.
Meng Xiankai - One of the best experts on this subject based on the ideXlab platform.
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Analysis of microstructure and tensile properties produced by cryogenic Laser Peening on 2024-T351 aluminum alloy
Vacuum, 2018Co-Authors: Li Jing, Jianzhong Zhou, Shu Huang, Feng Aixin, Yunjie Sun, Xuliang Tian, Yu Huang, Meng XiankaiAbstract:Abstract The microstructural response and tensile properties on 2024-T351 aluminum alloy specimens induced by cryogenic Laser Peening were investigated. The microstructure behaviors were characterized by transmission electron microscopic examination and electron backscattered diffraction analysis. Tensile properties tests at room temperature were also performed. The experimental results cleared that compared with room temperature Laser Peening, cryogenic Laser Peening can induce higher-density of dislocation and smaller-size grain, while the strength and plasticity of the processed 2024-T351 aluminum alloy were simultaneously increased. The analysis results suggested that the more excellent tensile properties were attributed to the more beneficial microstructural evolution induced by cryogenic Laser Peening.
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Investigation on mechanical properties and microstructural evolution of TC6 titanium alloy subjected to Laser Peening at cryogenic temperature
Materials Science and Engineering: A, 2018Co-Authors: Li Jing, Meng Xiankai, Jianzhong Zhou, Shu Huang, Feng Aixin, Sun Yunhui, Yunjie Sun, Xuliang Tian, Yu HuangAbstract:Abstract The aim of this study was to investigate the influence of the synergistic function of cryogenic temperature and ultrahigh strain rate deformation during the process of Cryogenic Laser Peening (CLP) on the mechanical properties and microstructural evolution of TC6 titanium alloy. The measurements of tensile properties at room and elevated temperatures, as well as micro-hardness on the cross-sectional direction were carried out. Meanwhile, the microstructural evolution was characterizated by Electron Backscattered Diffraction (EBSD) analysis and Transmission Electron Microscopy (TEM) observation. The experimental results demonstrated that cryogenic Laser Peening could significantly improve the strength and ductility, as well as the stability at elevated temperature condition of TC6 titanium alloy. At the same time, cryogenic Laser Peening could provide higher surface micro-hardness than room temperature Laser Peening (RT-LP), the surface micro-hardness of the specimen subjected to cryogenic Laser Peening increased by 4.86% than that of the specimen treated by room temperature Laser Peening. Additionally, cryogenic Laser Peening could generate finer grains and higher-density of dislocation structures, while large numbers of sub-grains and mechanical twins were also observed in the surface layer. Finally, the microscopic strengthening mechanism of cryogenic Laser Peening for better mechanical properties on TC6 titanium alloy was also analyzed in detail.
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Residual stress relaxation and its effects on the fatigue properties of Ti6Al4V alloy strengthened by warm Laser Peening
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2017Co-Authors: Meng Xiankai, Jianzhong Zhou, Su Chun, Shu Huang, Kaiyu Luo, Jie Sheng, Wensheng TanAbstract:Abstract A method combining experiment and simulation was used in this paper to study the effects of warm Laser Peening (WLP) on the residual stress relaxation (RSR) in Ti6Al4V titanium alloy. Moreover, the effects of RSR on fatigue properties and its mechanism were both revealed. Laser Peening experiments were conducted at room temperature (RT-LP) and elevated temperature (300 °C-WLP). Then the yield strengths of specimens were obtained through tensile experiments and their improvement induced by WLP was analyzed by microstructures. A finite element analysis was used to research the effects of RT-LP and 300 °C-WLP on the RSR during fatigue. Finally, the fatigue life and fracture microstructures were both measured and analyzed. The results indicate that the severe plastic strain induced by 300 °C-WLP results in lots of crossed acicular α phases with a short spacing, which promotes the interactions between α phases and leads to an increasing dislocation density. Therefore, the yield strength of 300 °C-WLPed specimens is much greater than RT-LPed samples based on the Hall-Petch relations. Besides, the simulated results show that the extended yield strength of 300 °C-WLPed specimens significantly decreases the d σ /d e during fatigue and thus reduces the relaxation of CRS. Moreover, it can be found that the fatigue life of 300 °C-WLPed specimens is subjected to an significant increase, which can be attributed to the increasing finished crack lengths and the decreasing RSR.
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Effects of Laser Peening with different coverage areas on fatigue crack growth properties of 6061-T6 aluminum alloy.
International Journal of Fatigue, 2013Co-Authors: Shu Huang, Meng Xiankai, Jianzhong Zhou, Kaiyu Luo, Jie Sheng, L D Zuo, Liming Dai, H.y. RuanAbstract:Abstract The effects of coverage area on fatigue crack growth (FCG) properties of 6061-T6 aluminum alloy subject to multiple Laser Peening (LP) impacts were investigated. Residual stress, micro-structure and fatigue striation pattern on fracture cross-sections were analyzed. Compressive residual stresses and dense dislocation arrangements can be found in the superficial layer after LP. LP coverage area has a direct influence on FCG properties as verified by different size of shell ridges and fatigue striation spacing on fracture cross-sections. Meanwhile, FCG rate decreases with the increase of compressive residual stresses distribution perpendicular to the crack growth direction in the initial FCG stage.
Raghu V. Prakash - One of the best experts on this subject based on the ideXlab platform.
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Effect of Laser Peening and shot Peening on fatigue striations during FCGR study of Ti6Al4V
International Journal of Fatigue, 2016Co-Authors: B. K. Pant, Raghu V. Prakash, A.h.v. Pavan, M. KamarajAbstract:Abstract The fatigue life of steam turbine blades is enhanced by subjecting its fir tree blade root section to mechanical treatments like shot Peening and Laser Peening to introduce compressive stresses in the surface layers. In the case of higher power rated steam turbines, light alloys such as Ti6Al4V are now being adopted in the last stage blades since their exit diameters are very large and hence it is not technically possible to use steels for these machines due to the enormous stresses that would be experienced at the blade roots. This paper studies the effect of shot Peening and Laser Peening on the fatigue crack growth of Ti6Al4V alloy at a stress ratio R of 0.1 and the changes observed in the fracture microstructure during the fatigue crack growth (FCGR). In specific, study of the striations developed during the FCGR on the fracture surface at regular intervals of crack movement have been recorded; an attempt has been made to correlate the striation spacing with crack front growth. It is observed that the fatigue life in the initial stages of FCGR testing is affected by the shot Peening effect whereas it is more affected by Laser Peening effect at higher values of delta K (ΔK). The effect of closure is seen in both the shot peened and Laser peened samples to different degrees.
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Effect of Laser Peening on Steel and Titanium Alloy for Power Applications
Volume 2A: Advanced Manufacturing, 2013Co-Authors: B. K. Pant, Raghu V. Prakash, M. KamarajAbstract:Low pressure steam turbine (LPST) blades are made of martensitic stainless steel and Ti6Al4V alloy for the different ratings of steam turbines due to their high strength and toughness. These blade roots have a fir tree profile and experience severe stress concentrations all along their notched sections during turbine operation. The fatigue life of these blades can be increased by introducing compressive stresses either by shot Peening or by Laser Peening. The present work deals with Laser Peening of these two materials to understand its effect on their fatigue properties, surface roughness and hardness. It is observed that Laser Peening has significantly enhanced fatigue life of Ti6Al4V alloy at 550 MPa stress as compared to the shot peened sample. The penetration depth of residual stress due to Laser Peening in the Ti6Al4V alloy was twice that due to shot Peening. However, the fatigue life of steel was found to be similar for both the shot peened as well as Laser peened samples. Similar response was observed from testing at lower stresses (400 MPa). Since the depth of penetration of compressive residual stresses for both the Laser peened as well as the shot peened samples were similar for steels, it can be concluded that the fatigue life is a strong function of the penetration depth.Copyright © 2013 by ASME
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Studies towards development of Laser Peening technology for martensitic stainless steel and titanium alloys for steam turbine applications
Materials Science and Engineering: A, 2013Co-Authors: B. K. Pant, Lalit M. Kukreja, Harish Kumar, A.h.v. Pavan, R. Sundar, Rakesh Kaul, K. Ranganathan, Kushvinder S. Bindra, S. M. Oak, Raghu V. PrakashAbstract:Abstract Fatigue is a major life limiting factor affecting service life of low pressure steam turbine blades which, depending on turbine rating, are generally made of martensitic stainless steel or Ti6Al4V alloy. The results of the present study has demonstrated that with respect to conventional shot Peening, Laser Peening brought more than two times longer mean fatigue life of Ti6Al4V alloy. Enhanced fatigue performance of Laser peened specimens was attributed to the deeper peened layer and smoother finish. In the case of DIN X20Cr13 stainless steel, Laser Peening did not register significant improvement in fatigue resistance over shot Peening. At maximum test stress of 550 MPa, DIN X20Cr13 stainless steel specimens, shot peened and Laser peened specimens exhibited comparable fatigue lives. However, at lower magnitude of maximum test stress of 400 MPa, Laser peened specimens displayed about 30% longer fatigue lives than their shot peened counterparts. Similar fatigue lives of shot peened and Laser peened specimens of DIN X20Cr13 stainless steel specimens is attributed to comparable magnitude of surface residual stress and case depth produced by the two Peening treatments.
B. K. Pant - One of the best experts on this subject based on the ideXlab platform.
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Effect of Laser Peening and shot Peening on fatigue striations during FCGR study of Ti6Al4V
International Journal of Fatigue, 2016Co-Authors: B. K. Pant, Raghu V. Prakash, A.h.v. Pavan, M. KamarajAbstract:Abstract The fatigue life of steam turbine blades is enhanced by subjecting its fir tree blade root section to mechanical treatments like shot Peening and Laser Peening to introduce compressive stresses in the surface layers. In the case of higher power rated steam turbines, light alloys such as Ti6Al4V are now being adopted in the last stage blades since their exit diameters are very large and hence it is not technically possible to use steels for these machines due to the enormous stresses that would be experienced at the blade roots. This paper studies the effect of shot Peening and Laser Peening on the fatigue crack growth of Ti6Al4V alloy at a stress ratio R of 0.1 and the changes observed in the fracture microstructure during the fatigue crack growth (FCGR). In specific, study of the striations developed during the FCGR on the fracture surface at regular intervals of crack movement have been recorded; an attempt has been made to correlate the striation spacing with crack front growth. It is observed that the fatigue life in the initial stages of FCGR testing is affected by the shot Peening effect whereas it is more affected by Laser Peening effect at higher values of delta K (ΔK). The effect of closure is seen in both the shot peened and Laser peened samples to different degrees.
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Effect of Laser Peening on Steel and Titanium Alloy for Power Applications
Volume 2A: Advanced Manufacturing, 2013Co-Authors: B. K. Pant, Raghu V. Prakash, M. KamarajAbstract:Low pressure steam turbine (LPST) blades are made of martensitic stainless steel and Ti6Al4V alloy for the different ratings of steam turbines due to their high strength and toughness. These blade roots have a fir tree profile and experience severe stress concentrations all along their notched sections during turbine operation. The fatigue life of these blades can be increased by introducing compressive stresses either by shot Peening or by Laser Peening. The present work deals with Laser Peening of these two materials to understand its effect on their fatigue properties, surface roughness and hardness. It is observed that Laser Peening has significantly enhanced fatigue life of Ti6Al4V alloy at 550 MPa stress as compared to the shot peened sample. The penetration depth of residual stress due to Laser Peening in the Ti6Al4V alloy was twice that due to shot Peening. However, the fatigue life of steel was found to be similar for both the shot peened as well as Laser peened samples. Similar response was observed from testing at lower stresses (400 MPa). Since the depth of penetration of compressive residual stresses for both the Laser peened as well as the shot peened samples were similar for steels, it can be concluded that the fatigue life is a strong function of the penetration depth.Copyright © 2013 by ASME
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Studies towards development of Laser Peening technology for martensitic stainless steel and titanium alloys for steam turbine applications
Materials Science and Engineering: A, 2013Co-Authors: B. K. Pant, Lalit M. Kukreja, Harish Kumar, A.h.v. Pavan, R. Sundar, Rakesh Kaul, K. Ranganathan, Kushvinder S. Bindra, S. M. Oak, Raghu V. PrakashAbstract:Abstract Fatigue is a major life limiting factor affecting service life of low pressure steam turbine blades which, depending on turbine rating, are generally made of martensitic stainless steel or Ti6Al4V alloy. The results of the present study has demonstrated that with respect to conventional shot Peening, Laser Peening brought more than two times longer mean fatigue life of Ti6Al4V alloy. Enhanced fatigue performance of Laser peened specimens was attributed to the deeper peened layer and smoother finish. In the case of DIN X20Cr13 stainless steel, Laser Peening did not register significant improvement in fatigue resistance over shot Peening. At maximum test stress of 550 MPa, DIN X20Cr13 stainless steel specimens, shot peened and Laser peened specimens exhibited comparable fatigue lives. However, at lower magnitude of maximum test stress of 400 MPa, Laser peened specimens displayed about 30% longer fatigue lives than their shot peened counterparts. Similar fatigue lives of shot peened and Laser peened specimens of DIN X20Cr13 stainless steel specimens is attributed to comparable magnitude of surface residual stress and case depth produced by the two Peening treatments.
