Comparative study of laser surface hardening of 50CrMo4 steel using continuous-wave laser and pulsed lasers with ms, ns, ps and fs pulse duration

Maharjan, Niroj; Zhou, Wei; Zhou, Yu; Guan, Yingchun; Wu, Naien

doi:10.1016/j.surfcoat.2019.03.036

Cited by 47 publications

(27 citation statements)

References 40 publications

(40 reference statements)

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“…When a high‐energy pulsed laser beam is focused onto a surface, it results in direct ablation of the surface material 38 . The ablation generates a plasma blow‐off that creates a recoil shock wave pressure inside the material.…”

Section: Resultsmentioning

confidence: 99%

“…When a high-energy pulsed laser beam is focused onto a surface, it results in direct ablation of the surface material. 38 The ablation generates a plasma blow-off that creates a recoil shock wave pressure inside the material. Confinement medium such as water overlay, being transparent to the laser beam, prevents the free expansion of the hot plasma formed due to ablation.…”

Section: Discussionmentioning

confidence: 99%

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Fatigue performance of laser shock peened Ti6Al4V and Al6061‐T6 alloys

Maharjan¹,

Chan²,

Ramesh³

et al. 2020

Fatigue Fract Eng Mat Struct

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Propagation of fatigue crack in laser shock peened metallic component is retarded by introduction of deep compressive residual stresses during the process. Apart from large compressive residual stress build‐up near the surface, surface topography is also significantly altered during laser shock peening. However, a systematic evaluation of the individual effects of residual stresses and surface topography as well as their interaction effects on fatigue crack initiation and growth is still lacking. This study investigates the effect of laser shock peening on near‐surface properties of Ti6Al4V and Al6061‐T6 alloys and how these changes dictate their overall fatigue performance. Microstructure, surface topography, hardness and residual stress state of the alloys are investigated before and after peening, and four‐point bending fatigue tests are performed to obtain Wöhler curves (S‐N curves) for each case. The results show that both surface residual stresses and surface topography influence the fatigue life of a component. Compressive residual stresses were induced to a depth beyond 1 mm for both alloys. Fatigue life of Ti6Al4V alloy increased by at least 1.28 times after laser shock peening due to the introduction of deep compressive residual stresses with minimal change in surface topography. By contrast, the improvement is nominal for Al6061‐T6 alloy due to the surface roughening effect introduced by laser peening, which results in early crack initiation and negates the beneficial effect of compressive residual stresses.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Fatigue performance of laser shock peened Ti6Al4V and Al6061‐T6 alloys

Maharjan¹,

Chan²,

Ramesh³

et al. 2020

Fatigue Fract Eng Mat Struct

View full text Add to dashboard Cite

show abstract

“…When a high energy pulsed laser beam is focused onto a surface, it results in direct ablation of the surface material [34]. The ablation generates a plasma blow-off which creates a recoil shock wave pressure inside the material.…”

Section: Discussionmentioning

confidence: 99%

Fatigue performance of laser shock peened Ti6Al4V and Al6061-T6 alloys

Maharjan¹,

Chan²,

Ramesh³

et al. 2020

Preprint

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Propagation of fatigue crack in laser shock peened metallic component is retarded by introduction of deep compressive residual stresses during the process. Apart from large compressive residual stress build-up near the surface, surface topography is also significantly altered during laser shock peening. However, a systematic evaluation of the individual effects of residual stresses and surface topography as well as their interaction effects on fatigue crack initiation and growth is still lacking. This study investigates the effect of laser shock peening on near surface properties of Ti6Al4V and Al6061-T6 alloys and how these changes dictate their overall fatigue performance. The results show that both surface residual stresses and surface topography influence the fatigue life of a component. It is found that fatigue life of Ti6Al4V alloy increased by at least 1.28 times after laser shock peening. In contrast, the improvement is minimal for Al6061-T6 alloy due to the surface roughening effect introduced by laser peening which results in early crack initiation and negates the beneficial effect of compressive residual stresses.

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“…As shown by these authors [15], the only phase transformation introduced in the surface layer of material by this surface treatment is melting of a layer of material with a thickness varying in the 65–130 nm range. The laser treatment also induces the formation of defects in a layer of material less than 1 µm deep, as shown by Sedao et al [70], but these defects do not seem enough to change significantly the surface hardness of the material [71], so the observed effects are mainly to be accounted by the surface topography.…”

Section: Discussionmentioning

confidence: 99%

Influence of Femtosecond Laser Surface Nanotexturing on the Friction Behavior of Silicon Sliding Against PTFE

et al. 2019

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The aim of the present work was to investigate the influence of laser-induced periodic surface structures (LIPSS) produced by femtosecond laser on the friction behavior of silicon sliding on polytetrafluoroethylene (PTFE) in unlubricated conditions. Tribological tests were performed on polished and textured samples in air using a ball-on-flat nanotribometer, in order to evaluate the friction coefficient of polished and textured silicon samples, parallel and perpendicularly to the LIPSS orientation. In the polished specimens, the friction coefficient decreases with testing time at 5 mN, while it increases slightly at 25 mN. It also decreases with increasing applied load. For the textured specimens, the friction coefficient tends to decrease with testing time in both sliding directions studied. In the parallel sliding direction, the friction coefficient decreases with increasing load, attaining values similar to those measured for the polished specimen, while it is independent of the applied load in the perpendicular sliding direction, exhibiting values lower than in the two other cases. These results can be explained by variations in the main contributions to friction and in the wear mechanisms. The influence of the temperature increase at the interface and the consequent changes in the crystalline phases of PTFE are also considered.

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Comparative study of laser surface hardening of 50CrMo4 steel using continuous-wave laser and pulsed lasers with ms, ns, ps and fs pulse duration

Cited by 47 publications

References 40 publications

Fatigue performance of laser shock peened Ti6Al4V and Al6061‐T6 alloys

Fatigue performance of laser shock peened Ti6Al4V and Al6061‐T6 alloys

Fatigue performance of laser shock peened Ti6Al4V and Al6061-T6 alloys

Influence of Femtosecond Laser Surface Nanotexturing on the Friction Behavior of Silicon Sliding Against PTFE

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