1、RecommendedPractices forLaser BeamWelding, Cutting,and AlliedProcessesAWS C7.2M:2010An American National StandardAWS C7.2M:2010An American National StandardApproved by theAmerican National Standards InstituteJune 24, 2010Recommended Practices for Laser Beam Welding, Cutting, and Allied Processes2ndE
2、ditionSupersedes ANSI/AWS C7.2:1998Prepared by theAmerican Welding Society (AWS) C7 Committee on High-Energy Beam Welding and CuttingUnder the Direction of theAWS Technical Activities CommitteeApproved by theAWS Board of DirectorsAbstractThis document presents recommended practices for laser beam we
3、lding, cutting, drilling, and transformation hardening.It is intended to cover common applications of the process. Processes definitions, safe practices, general process require-ments and inspection criteria are provided.International Standard Book Number: 978-0-87171-777-1American Welding Society55
4、0 N.W. LeJeune Road, Miami, FL 33126 2010 by American Welding SocietyAll rights reservedPrinted in the United States of AmericaPhotocopy Rights. No portion of this standard may be reproduced, stored in a retrieval system, or transmitted in anyform, including mechanical, photocopying, recording, or o
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6、 appro-priate fee is paid to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, tel: (978) 750-8400;Internet: .AWS C7.2M:2010iiAWS C7.2M:2010iiiStatement on the Use of American Welding Society StandardsAll standards (codes, specifications, recommended practices, methods, classifi
7、cations, and guides) of the AmericanWelding Society (AWS) are voluntary consensus standards that have been developed in accordance with the rules of theAmerican National Standards Institute (ANSI). When AWS American National Standards are either incorporated in, ormade part of, documents that are in
8、cluded in federal or state laws and regulations, or the regulations of other governmen-tal bodies, their provisions carry the full legal authority of the statute. In such cases, any changes in those AWS standardsmust be approved by the governmental body having statutory jurisdiction before they can
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10、tween the contracting parties.AWS American National Standards are developed through a consensus standards development process that bringstogether volunteers representing varied viewpoints and interests to achieve consensus. While the AWS administers theprocess and establishes rules to promote fairne
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18、ion: Managing Director, Technical Services Division, 550 N.W. LeJeune Road, Miami, FL 33126 (see Annex B).With regard to technical inquiries made concerning AWS standards, oral opinions on AWS standards may be rendered.These opinions are offered solely as a convenience to users of this standard, and
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20、opinions are informal and should not be used as a substitute for an official interpretation.This standard is subject to revision at any time by the AWS C7 Committee on High-Energy Beam Welding and Cutting.It must be reviewed every five years, and if not revised, it must be either reaffirmed or withd
21、rawn. Comments (recom-mendations, additions, or deletions) and any pertinent data that may be of use in improving this standard are required andshould be addressed to AWS Headquarters. Such comments will receive careful consideration by the AWS C7Committee on High-Energy Beam Welding and Cutting and
22、 the author of the comments will be informed of theCommittees response to the comments. Guests are invited to attend all meetings of the AWS C7 Committee on High-Energy Beam Welding and Cutting to express their comments verbally. Procedures for appeal of an adverse decision con-cerning all such comm
23、ents are provided in the Rules of Operation of the Technical Activities Committee. A copy of theseRules can be obtained from the American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126.AWS C7.2M:2010ivThis page is intentionally blank.AWS C7.2M:2010vPersonnelAWS C7 Committee on High-Energy B
24、eam Welding and CuttingP. W. Hochanadel, Chair Los Alamos National LaboratoryT. A. Palmer, 1st Vice-Chair Lawrence Livermore National LaboratoryK. W. Lachenberg, 2nd Vice-Chair Sciaky, IncorporatedM. Rubin, Secretary American Welding SocietyP. Blomquist Applied Thermal Sciences, IncorporatedD. D. Ka
25、utz Los Alamos National LaboratoryG. R. LaFlamme PTR Precision Technologies Inc.E. D. Levert Lockheed Martin Missiles and Fire ControlAdvisors to the AWS C7 Committee on High-Energy Beam Welding and CuttingP. E. Denney Connecticut Center for Advanced TechnologyR. D. Dixon RetiredP. W. Fuerschbach Sa
26、ndia National LaboratoryR. W. Messler Jr. Rensselaer Polytechnic InstituteJ. O. Milewski Los Alamos National LaboratoryT. M. Mustaleski BWXT Y-12 LLCD. E. Powers PTR Precision Technologies, IncorporatedR. C. Salo Sciaky, IncorporatedAWS C7C Subcommittee on Laser Beam Welding and CuttingP. Blomquist,
27、 Chair Applied Thermal Sciences, IncorporatedP. E. Denney, Vice-Chair Connecticut Center for Advanced TechnologyM. Rubin, Secretary American Welding SocietyR. D. Bucurel WEC Welding other diode lasersemitting in the infrared are used for material processing.AWS C7.2M:20103disk laser. Characterized b
28、y a heat sink and laser output that are realized on opposite sides of a thin layer of active gainmedium. Despite their name, disk lasers do not have to be circular; other shapes have also been tried. Disk lasersshould not be confused with Laserdiscs, which are a disk-shaped optical storage medium.di
29、vergence. The expansion angle (measured in milliradians) of an optical beam in the far field. In specifying the beamdivergence, one should note whether it is the full-angle or half-angle divergence.divergence, full-angle. The expansion angle of an optical beam measure on both sides of the optic axis
30、.divergence, half-angle. The expansion angle of an optical beam measured from the optic axis to the extremities of thebeam (as specified by the beam diameter).doping. The process of adding a small concentration of a lasing ion or atom to a host material. The host material supportsthe dopants, influe
31、nces the emission of energy from the dopants, and conducts away excess heat.dross. The melted and resolidified metal or metal oxide produced during cutting or drilling that adheres to the top or bottom edge of a cut or drilled surface.duty cycle. The fraction of time that a repetitively pulsed laser
32、 is producing pulsed output.effective spot diameter. See melted spot diameter.energy density. Laser output energy per unit area, expressed, for example, as J/cm2.energy transfer efficiency. The ratio of the heat absorbed by the workpiece to the incident laser beam energy.enhanced pulse. A laser puls
33、e output containing an initial short-duration burst of power when the discharge is first ener-gized, which subsequently decays to a lower level of output. See leading edge spike.excimer laser. A laser that emits ultraviolet energy from molecules called excimers that are created in pulsed electricald
34、ischarges and exist only for a very short period of time, on the order of nanoseconds. Excimer lasers use combina-tions of a gas such as argon, xenon, or krypton with halogens such as fluorine. Wavelengths from 0.193 to 0.348 mhave been generated.excitation. Process of transferring energy from the e
35、nergy source to the active medium.far field. Far from the laser source; a term used in describing how a laser beam propagates. Mathematically, far fieldoccurs at a distance D such thatD w2o(Equation 1)where, = laser wavelengthwo= minimum radius of the output laser beamfast axial flow (FAF). A laser
36、design in which the active medium (gas) is transported at a high speed along the opticalaxis of the laser resonator so that it can be cooled by external heat exchangers. In industrial CO2lasers, where thisdesign is common, either a Roots pump or a centrifugal compressor is used to move the laser gas
37、 through the discharge region and heat exchangers.fiber laser. A solid-state laser design in which the active medium is a doped optical fiber. Ytterbium is the most commonactive element doped into the fiber.fiber optic. A small diameter solid fiber made of a transparent material such as fused quartz
38、 (or fused silica) and coatedto achieve total internal reflection of a laser beam along its path. A fiber optic beam delivery system transmits theoutput power of the laser to the workpiece and can be bent at a shallow radius, eliminating the use of mirrors.flashlamp. A device that converts electrica
39、l energy into light by means of a sudden electrical discharge. Flashlamps area source of excitation in a pulsed solid-state laser.fluence. See energy density.fluence threshold. The energy density level (measured in joules/cm2) at the surface of a material, at which there is sufficient energy to caus
40、e molecular bonds to break or some interaction to take place.AWS C7.2M:20104F-number. The ratio of the focal length of a lens or focusing mirror to the diameter of the beam incident on the lens ormirror. Note the definition is somewhat different than that for photographic systems.focal length. In a
41、lens or lens system, the distance from the principal plane, the surface at which the projections of anentering and exiting ray intersect, to the focal point. In a thick lens or system of lenses, the principal plane is ofteninside the lens itself; for setup purposes, operators often use the back foca
42、l length, which is the distance from thefront surface of a focusing lens or mirror system to the focal point.focal plane. A plane through the focal point at right angles to the direction of propagation of the beam where the minimum spot size occurs.focal point. A nonstandard term for focal spot.foca
43、l spot. A location at which the beam has the most concentrated energy and the smallest cross-sectional area.focusing head. An assembly located near the end of the beam path that is used to converge an unfocused laser beam forprocessing materials. The assembly consists of one or more focusing lenses
44、or mirrors, and may include assist- andpurge-gas delivery system, a focal point adjustment mechanism, and optic protection devices.following error. In CNC equipment, the deviation of the actual path traced by the focused beam or by a machine toolfrom the programmed motion. This error is most importa
45、nt when making abrupt turns at high speed and can bereduced by slowing the speed.fused quartz. A glass formed by heating crystalline quartz to white heat, then cooling. It has a lower index of refractionthan crystal quartz.fused silica. Glass consisting of almost pure silicon dioxide. It is purer th
46、an fused quartz.gallium arsenide (GaAs). A synthetically grown crystal used, among other things, in laser optics like lenses and mirrors.gas laser. A laser in which the lasing medium is a gas. This type of laser is subdivided by medium into atomic (such asheliumneon laser), molecular (such as carbon
47、 dioxide laser), and ionic (such as argon, krypton, xenon, orheliumcadmium laser, for example). Excimer lasers are also gas lasers.gas recirculation. A system to circulate the laser gas through the active laser region and the heat exchangers in a closedloop. The gases are cooled and re-excited conti
48、nually. Commonly used in high-power lasers, a means to circulatethe laser gas through the active laser region and heat exchangers in a closed loop.Gaussian distribution. A symmetric two-dimensional equation which approximately describes the spatial power distribution of many laser beams. The equatio
49、n of the Gaussian distribution is:P(r) = Poe2r1w2(Equation 2)where,P(r) = power densityPo= maximum power densityr = radial distance out from the center of distributionW = radius at which power density is 0.135 times maximum(see beam diameter)Gaussian mode. The fundamental transverse mode of a stable laser resonator (called TEM00mode). A laser operating inthis mode produces a beam having a Gaussian distribution.glass laser. A laser in which the active medium is an optical glass doped with a small concentration of a lasing material,typically neodymium. Glass is easier to produ
