Dec 14, 2018 nickeltitanium niti alloy is an attractive material for biomedical implant applications. Laser shock peening lsp is an efficient surface treatment technique used to improve the fatigue performance of metals. Effects of laser shock peening on the surface integrity of 18 % ni. A study on the surface morphology evolution of the gh4619. Laser peening is a more targeted and controlled process than shot peening. Lsp can greatly improve the resistance of a material to crack initiation and propagation brought on by cyclic loading and fatigue. The purpose of this paper is to model 3d shock pressure and. Laser peening was first developed at battelle laboratory circa 1965, but was not commercialized for years due to the lack of a reliable, high repetition rate, high averagepower laser. Dec 17, 2019 laser shock peening lsp is one of the widely used surface processing techniques for tailoring functional behavior of surfaces. Navy has announced a laser shock peening facility at cherry point, n.
Dynamic response and residual stress fields of ti6al4v. Traditional lsp process involves using a protective bilayer of thin metal foil and vacuum grease in order to protect the workpiece from direct laser ablation. Short energy pulses are then focused to create a highpressure pulse at the surface of the ablative layer, producing a shock wave. In this study, laser shock peening lsp has been applied to ods 304 austenitic steels, during which a high density of dislocations, stacking faults, and deformation twins are generated in the near surface of the material due to the interaction of laser driven shock waves and the austenitic steel matrix. Finite element modeling of hybrid additive manufacturing. Peening is normally a cold work process, with laser peening being a notable exception. Laser shock peening of oxidedispersionstrengthened. Shock peening of engineering ceramics using contactless energy beams pratik shukla 3 could cost up to 30 k gbp. Pdf laser peening process and its impact on materials.
Warm laser shock peening driven nanostructures and their. A prestrain laser shock peening method is proposed to fabricate fatigueresistant nanocrystalline niti with graded nanolayers and compressive residual stress layers. In response to the rapidly expanding plasma, a shock wave peak pressure 100 kbars is generated in the part, and run into the material, creating a plastic strain that. Laser shock peening free download as powerpoint presentation. Characterization of plastic deformation induced by microscale laser shock peening. Laser shock peening produces a compressive residual stress in the surface of metallic materials, which significantly increases fatigue life in applications where. Lsp is an innovative surface treatment 5 that can increase the fatigue strength of metallic parts by generating. Laser shock peening of ceramics using litron lasers youtube. Nickeltitanium niti alloy is an attractive material for biomedical implant applications. Compared to mechanical shock peening, it is a noncontact process.
It is found that the nanostructure shows a gradient distribution from middle region. In this study, the effects of laser shock peening lsp on the biocompatibility, corrosion resistance, ion release rate and hardness of niti were characterized. Modeling, simulations, and applications find, read and cite all the research you. Lsp is superior to the mechanical shot peening in the benefits of deeper penetration of compressive stress, shorter process time 7 ns for 1 laser pulse, precise control, accuracy, flexibility and no contamination. Nanocrystallization in the duplex ti6al4v alloy processed. Abstract laser shock peening lsp, or hardening the material surface by laser shock wave is very modern and progressive technology, which allows a significant increase in. Lsp has been used to enhance friction, wear, and mechanical properties. F35s to get warfare system upgrades, laser shock peening. Posttreatment of arcwelded aluminum alloy joints by laser shock. Effect of laser shock peening on the wearcorrosion.
Aug 17, 2015 the video filmed at university of chester laser engineering and manufacturing research group, uk in conjunction with dr. Yag or a co 2 high power laser system brand new would cost up to 200 k to 250 k gbp. Laser shock peening lsp, an innovative surface treatment technique, generates compressive residual stress on the surface of metallic components to improve their fatigue performance, wear resistance and corrosion resistance. Effects of laser shock peening on the corrosion behavior. Laser is irradiated on the metal surface under confinement layer. In this study, laser shock peening lsp has been applied to ods 304 austenitic steels, during which a high density of dislocations, stacking faults, and deformation twins are generated in the near surface of the material due to the interaction of laserdriven shock waves and the austenitic steel matrix. Laser shock peening of aluminum and titanium using dipole. Here, we use laser shock peening lsp as a surface treatment for mitigation of stress corrosion cracking scc, and explore how the material differences of 304. Laser peening or laser shock peening counteracts metal fatigue to prevent corrosion and cracking of missioncritical parts. Deeper residual compressive stress enabling better resistance to. Enhance fatigue resistance of nanocrystalline niti by laser. Laser peening generates a stronger shock wave at the part surface, and the benefits of laser peening remain stable at higher temperatures.
Laser peening lp, or laser shock peening lsp, is a surface engineering process used to impart beneficial residual stresses in materials. The development of the lsp technique and its numerous advantages over the conventional shot peening sp such as better surface finish, higher depths of residual stress and uniform distribution of intensity were discussed. Laser shock peening of bulk metallic glasses part 1. The residual elastic strain varies with the distance from the laser shock peened surface. Laser peening is a cold working process that forms a compressive residual stress layer on gearteeth surfaces by impacting them with a highenergy, pulsed laser beam 30. Lawrence department of mechanical engineering, columbia university, new york 10027, usa abstract. During the laser shock peening, an acoustic emission sensor at a defined position is used to collect the acoustic wave signals that propagate in the air. The laser shock peening laboratory showing target station apparatus. Improvement in fatigue performance of aluminium alloy.
The acoustic wave signal is sampled, stored, digitally filtered and analyzed by the online laser shock peening detection system. Laser shock peening lsp is a surface treatment which improves the fatigue performance of metallic structures by introducing compressive residual stresses. Effects of laser shock peening on mechanical properties and. Residual elastic strain due to laser shock peening.
The effect s of peak pressure and layer thickness were studied when coupling laser shock peening with selective laser melting. Pdf laser peening process and its impact on materials properties. The purpose of this paper is to model 3d shock pressure and dynamic mechanical behavior at high strain rates. Lasershock peening lsp was first used by battelle columbus laboratories in 1974 ref. These deeper residual stresses have proven to signifi. The effects of shot and laser peening on fatigue life and. Before processing, an opaque overlay typically black paint or tape and a transparent overlay.
Laser shock peening from curtiss wright surface technologies. An absorption overlay disposed on the target surface of the workpiece absorbs the laser beam. Laser peening is not a replacement for controlled shot peening, but has additional advantages that. Abstract laser shock peening lsp, or hardening the material surface by laser shock wave is very modern and progressive technology, which allows a significant increase in fatigue life of cyclically loaded parts.
Experimental and numerical investigation of residual stresses in. Laser peen forming we utilize our laser peening process to form and shape the contour of metal components such as wing skins. Laser shock peening stress corrosion cracking is a phenomenon that can lead to sudden failure of metallic components. Laser shock peening and mechanical shot peening processes. In this process, the surface of the material is covered with a thin layer of opaque material such as black paint and over this layer a thick layer of transparent material such as water is placed. Laser peening equipment and services lsp technologies. Pdf laser shock peening for fatigue resistance allan. The effect of laser shock peening on the life and failure mode of a. The deep, high magnitude compressive residual stresses induced by laser peening increase the resistance of materials to surfacerelated failures, such as fatigue, fretting fatigue and stress corrosion cracking. Acoustic wave detection of laser shock peening opto. Laser shock peening is been used to prolong the fatigue life of critical aerospace components such as turbine engines and aircraft structures as well as for wing skins to achieve the requirements of the new generation of intercontinental aircraft.
Laser shock peening and conventional mechanical shot peening are both comparable processes generally applicable to surface treat various metals and alloys. Apodizers for laser peening systems abstract a method and apparatus for improving the functionality, quality, and usefulness of a beam of coherent energy used in laser shock processing by utilizing an apodizer within the oscillator or amplifier of a laser. Effects of laser shock peening on the corrosion behavior and. Dynamic response and residual stress fields of ti6al4v alloy. Laser shock peening produces a compressive residual stress in the surface of metallic materials, which significantly increases fatigue life in applications where failure is caused by surfaceiniti. Laser shock peening laser shock peening of 6061t6 aluminum alloy rubiogonzalez c. Pdf characterization of plastic deformation induced by. Apodizers for laser peening systems lsp technologies. Laser peening process is proposed to carry out using lowenergy lasers. Effect of laser shock peening on the microstructures and. Laser peening laser peening induces exceptionally deep residual compressive stresses which enhance the fatigue strength and durability of critical metallic components. This paper presents the after effect of laser shock peening lsp on aa2024 alloy specimen irradiated with the lspiral scanning pattern at different pulse energies.
Laser shock peening lsp is a relatively new surface treatment for metallic materials. Material influence on mitigation of stress corrosion. Domec pradeep kumar mallenahalli john fletcher wheeler original assignee franks international, inc. Effects of laser shock peening on mechanical properties. Feasibility study on laser microwelding and laser shock. Lsp is a process to induce compressive residual stresses using shock waves generated by laser pulses. Pdf laser shock processing and its effects on microstructure and. Laser peening is proven to increase the lifespan of metal parts by five to 10 times the life of untreated parts even components treated with shot peening, ulrasonic peening, and other conventional processes. Reprinted with permission from the metal society of aime laser. Warm laser shock peening wlsp is an effective surface treatment method to improve the stability of microstructure and residual stress of metallic materials at high temperature, which takes the advantages of both lsp and dsa.
Laser shock peening is a surface treatment technique that relies on inducing a shock compression wave propagating from the material surface by rapid discharge of energy within an absorptive layer of, say, carbon. Laser shock peening lsp is a surface treatment process to improve surface integrity. A brief introduction covering lsp process, lsp on various materials and some innovative applications of lsp have been discussed. Laser shock peening in the recent years has proved to be successful with steels, aluminium and titanium surfaces and metallic alloys in general. Compared to traditional laser shock peening lsp, warm laser shock peening wlsp i.
Laser peening process laser peening is not a thermal treatment. Process control techniques for laser peening metals. Although it is believed that the shock wave induced by laser abrasion has been used for submerged laser peening 27, the impact generated by collapsing bubbles developed after laser abrasion, and which behave in the same way as cavitation bubbles, was larger than that due to the laser abrasion 28. Higounenc1 1 metal improvement company i curtiss wright surface technologies, bayonne, france abstract in laser peening lp, compared to shot peening sp, the magnitude of residual compressive. A highenergy laser apparatus can be utilized to direct an intense laser beam through a confining medium and onto the target surface of a workpiece. Laser shock peeningforming laser materials processing lab.
In laser peening, an ablative layer, usually tape or paint, is applied to absorb laser energy. The xray diffraction analysis of the lsp treated specimens were compared with the untreated specimen. Peening is the process of working a metals surface to improve its material properties, usually by mechanical means, such as hammer blows, by blasting with shot shot peening or blasts of light beams with laser peening. To illustrate the dynamic response during lsp and residual stress. The deeper compressive stress achieved by laser peening allows the formation of thicker sections and tighter curvatures. Feasibility study on laser microwelding and laser shock peening using femtosecond laser pulses by dongkyun lee a dissertation submitted in partial ful. Shock peening of engineering ceramics using contactless. Laser peening, or laser shock peening, is the process of hardening or peening metal using a powerful laser. The laser beam passes through the transparent material. The surface morphology indicates an increase in surface roughness after lsp. Laser shock peening air an extension of conventional peening laser peening provides highly compressive surface residual stress deep layer of compressive residual stress smooth surface excellent process control laser near field image laser peened aluminum. Warm laser shock peening is an innovative manufacturing process that integrates laser shock peening and dynamic aging to improve materials fatigue performance. The freeform geometries of these tools such as dental scalers, bring challenges to surface operations such as shot peening and laser shock peening lsp.
The response of materials after microscale laser shock peening lsp was experimentally. As laser technology has developed rapidly in recent years, laser shock peening lsp is now applied in the postprocessing enhancement of metal weld joints. Priority date the priority date is an assumption and is not a legal conclusion. Aug 28, 2019 warm laser shock peening wlsp is an effective surface treatment method to improve the stability of microstructure and residual stress of metallic materials at high temperature, which takes the advantages of both lsp and dsa. Whereas shot peening may be applied over the entire surface of a part, laser peening is only applied to critical, fatigueprone areas. Nevertheless, minimal research has been conducted on laser shock peening and mechanical shot peening of technical grade ceramics. Laser shock peening lsp is an advanced surface enhancement technique for metallic materials to improve fatigue, corrosion and wearing resistance. Characterization of plastic deformation induced by. Lspt uses its patented laserpeen process to provide laser peening production services at our facility for customers that include power generation and aerospace oems, allowing them to achieve the component life extensions and reduce operational. Shock waves laser beam plasma ods steel plasmaconfining media sacrificial layer figure 1. Critical laser parameters for lsp such as laser energy, pulse width, wavelength, overlap rate, role of sacrificial coating and. Commercial advantages offered by the laser systems such as flexibility, deep penetration of laserinduced shocks with precise control of the thermal pulses, shorter process times, high speeds, accuracy and aesthetics are. Introduction laser shock peening lsp process is one of the surface treatments to induce residual compressive stress on the material surface to improve the fatigue property of material.
Laser peening system laser peening is a rapidly developing surface treatment process that puts the surface in a state of compressive residual stress. A laser shock peening process for producing one or more compressive residual stress regions in a medical device is disclosed. Lsp is a transient process with laser pulse duration time on the order of 10 ns. Laser shock peening lsp is one of the widely used surface processing techniques for tailoring functional behavior of surfaces. Also in this area the residual tensile stresses turns into residual compressive stresses. Advances in microscale laser shock peening 507 micronlevel spatial resolution in copper thinfilm samples by recording the diffraction intensity contrast of the underlying single crystal silicon substrate6. This phenomenon occurred because of the permanent reverse plastic deformation generated at laser spot center. Laser shock peeningforming l aser bending is a noncontact forming method for sheet metals, in which the sheet metal can be bent, shaped and precision aligned with the use of straight or curved laser scan lines to acquire desirable three dimensional 3d features.
Lsp can greatly improve the resistance of a material to c. Critical laser parameters for lsp such as laser energy, pulse width, wavelength, overlap rate, role of sacrificial coating and transparent overlay are. Pdf download for residual elastic strain due to laser shock peening. Laser shock peening deformation engineering fatigue. The laser spot diameter was adjusted to 3 mm on the target surface. Laser peening is not a replacement for controlled shot peening, but has additional advantages that can influence which method to use. Laser shock peening lsp was first used by battelle columbus laboratories in 1974 ref. Pratik shukla shows the effect of laser shock peening of advanced ceramics. Lsp technologies lspt is the worlds premier provider of laser peening services and equipment. Laser peening process and its impact on materials properties.
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