1、Specification for Automotive Weld QualityResistance Spot Welding of AluminumAWS D8.2M:2017An American National StandardAWS D8.2M:2017An American National StandardApproved byAmerican National Standards InstituteMarch 9, 2017Specification forAutomotive Weld QualityResistance Spot Welding of AluminumFi
2、rst EditionPrepared by theAmerican Welding Society (AWS) D8 Committee on Automotive WeldingUnder the Direction of theAWS Technical Activities CommitteeApproved by theAWS Board of DirectorsAbstractThis document contains both visual and measurable acceptance criteria for resistance spot welds in alumi
3、num. The information contained herein may be used as an aid by designers, resistance welding equipment manufacturers, welded product producers, and others involved in the automotive industry and resistance spot welding of aluminum.AWS D8.2M:2017iiISBN: 978-0-87171-910-2 2017 by American Welding Soci
4、etyAll 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 any form, including mechanical, photocopying, recording, or otherwise, without the prior written permission of the copyright o
5、wner.Authorization to photocopy items for internal, personal, or educational classroom use only or the internal, personal, or educational classroom use only of specific clients is granted by the American Welding Society provided that the appropri-ate fee is paid to the Copyright Clearance Center, 22
6、2 Rosewood Drive, Danvers, MA 01923, tel: (978) 7508400; Internet: AWS D8.2M:2017iiiStatement on the Use of American Welding Society StandardsAll standards (codes, specifications, recommended practices, methods, classifications, and guides) of the American Welding Society (AWS) are voluntary consens
7、us standards that have been developed in accordance with the rules of the American National Standards Institute (ANSI). When AWS American National Standards are either incorporated in, or made part of, documents that are included in federal or state laws and regulations, or the regulations of other
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9、arry the full legal authority of the contract or other document that invokes the AWS standards. Where this contractual relationship exists, changes in or deviations from requirements of an AWS standard must be by agreement between the contracting parties.AWS American National Standards are developed
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18、sed to the American Welding Society, Attention: Managing Director, Standards Development, 8669 NW 36 St, # 130, Miami, FL 33166 (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 conv
19、enience to users of this standard, and they do not constitute professional advice. Such opinions represent only the personal opinions of the particular individuals giving them. These individuals do not speak on behalf of AWS, nor do these oral opinions constitute official or unofficial opinions or i
20、nterpretations of AWS. In addi-tion, oral 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 D8 Committee on Automotive Welding. It must be reviewed every five years, and if not revised, it must be e
21、ither reaffirmed or withdrawn. Comments (recommendations, additions, or deletions) and any pertinent data that may be of use in improving this standard are requested and should be addressed to AWS Headquarters. Such comments will receive careful consideration by the AWS D8 Committee on Automotive We
22、lding and the author of the comments will be informed of the Committees response to the comments. Guests are invited to attend all meetings of the AWS D8 Committee on Automotive Welding to express their comments verbally. Procedures for appeal of an adverse decision concerning all such comments are
23、provided in the Rules of Operation of the Technical Activities Committee. A copy of these Rules can be obtained from the American Welding Society, 8669 NW 36 St, # 130, Miami, FL 33166.AWS D8.2M:2017ivThis page is intentionally blank.AWS D8.2M:2017vPersonnelAWS D8 Committee on Automotive WeldingD. L
24、. Galiher, Chair Tower InternationalT. Coon, Vice Chair Ford Motor CompanyM. D. Tumuluru, Second Vice Chair U. S. SteelA. I. Babinski, Secretary American Welding SocietyW. H. Brafford ConsultantE. Cross Meggitt Aircraft Braking SystemsJ. W. Dolfi ConsultantD. F. Hart ITW WeldingF. W. Hunt Hitachi Am
25、erica, Ltd.J. G. Hunt AET IntegrationS. C. Kelley ArcelorMittalD. P. Kelly Fusion Welding SolutionsD. R. Kolodziej ConsultantD. F. Maatz R 2) Spot welds with surface cracks adjacent to the periphery of the electrode impression (see Figure 3).5.1.3 Holes. A weld is discrepant when, upon visual inspec
26、tion without a magnification device, any opening contained within the electrode impression is found extending through the stack-up.5.1.4 Indentation. Indentation is the ratio of the amount of weld depression to the pre-welded sheet thickness, expressed as a percentage. Indentation should be less tha
27、n 30% of the thickness of each outside sheet of the welded joint, unless otherwise specified on the engineering drawing (see Figure 4). Care must be taken during measurement if distortion is present. Distortion must not add to the value of the indentation.5.2 Destructive Inspection Metallographic Cr
28、iteria5.2.1 Nugget Width. An acceptable weld has a nugget width greater than or equal to the minimum weld size shown in Table 1 unless specified otherwise on the controlling engineering documents. An illustration of nugget width is shown in Figure 5. Information on weld specimen preparation for nugg
29、et width measurement is contained in AWS D8.9M, Test Methods for Evaluating the Resistance Spot Welding Behavior of Automotive Sheet Steel Materials. When determining aFigure 2Minimum Edge DistanceFigure 3Surface CracksAWS D8.2M:20175Figure 4Indentation MeasurementTable 1 Minimum Acceptable Weld Siz
30、eaGoverning MetalThickness (t) (mm)Weld Sizeb(mm)0.600.80 3.60.811.00 4.01.011.30 4.51.311.60 5.01.611.90 5.51.912.30 6.02.312.70 6.52.713.10 7.03.113.60 7.5a. Weld sizes are calculated to ensure that weld size will always exceed 4*sqrt(t).b. For sheet thicknesses greater than 3.60 mm, the minimum w
31、eld size is 4*sqrt(t).AWS D8.2M:20176the nugget width of a weld that has already been destructively tested, the cross section must be taken through what appears to be the minimum dimension of the fused area. The purpose of sectioning the minimum dimension is to verify the accuracy of the destructive
32、 evaluation and not intended to classify the weld exclusively.5.2.2 Penetration. Penetration is the ratio of the nuggets maximum depth of fusion to the pre-welded sheet thickness, expressed as a percentage. Penetration must exceed 20% of the pre-welded sheet thickness into each sheet of the weldment
33、 (see Figure 6).Figure 6Penetration Measurement5.2.3 Porosity. Porosity measurement includes voids having a major length (L) greater than 1 t of the GMT and a minor dimension greater than 0.2 t of the GMT and the porosity (V) is contained inside the 85% of the nugget. Examination shall occur at a ma
34、gnification of 10X. A weld is discrepant when any of the following conditions is present:1. Sum of all areas of porosity (e.g., Area V1 + Area V2 + Area V3) is greater than 25% of the nugget area.2. Porosity intersects the heat affected zone (HAZ).NOTE: Higher magnifications may be used to aid area
35、or length measurements using metallographic viewing aids.Figure 5Attributes of a Spot Weld Measured from a Cross SectionAWS D8.2M:201775.2.4 Internal Cracks. Cracks observed in a weld cross section are considered internal cracks. Welds with cracks located in the nugget or HAZ meeting any one of the
36、criteria listed in Figure 8 are considered discrepant. Examination shall occur at a magnification of 10X. A weld is discrepant when any of the following conditions is present:1. Sum of all lengths in the fusion zone (e.g., L1 + L2 + L3) 25% of Nugget Width.2. Cracks in the HAZ (i.e. L4) or area boun
37、ded by the inboard 15% of the fusion zone (L1) where the area extends 15% of the fusion zone periphery and its center. An exception can be considered for those that would have been deemed acceptable by surface inspection and do not extend into the fusion zone.NOTE: Higher magnifications may be used
38、to aid area or length measurements using metallographic viewing aids.15% INBOARD OF FUSION ZONEPERIPHERY OF THE NUGGETV1V2V3Figure 7Examples of Discrepant Voids in the NuggetFigure 8Example of Discrepant Internal CracksAWS D8.2M:201785.3 Destructive Inspection Peel and Chisel CriteriaDestructive pee
39、l and chisel testing will result in different fracture modes depending on the material thickness, material composition, material strength, part geometry, or the type and rates of loading. The basic fracture modes are button pull, partial thickness fracture, interfacial fracture, or combinations ther
40、eof.5.3.1 Weld Size. In destructive testing, weld size is determined by measuring the known fused area. In most instances this means measuring only button and partial thickness fractures (i.e. material protruding from one of the previously welded sheets). Interfacial fractures can be included in the
41、 measurement when substantiated by the amount of deformation of the metal adjacent to the weld and the level of effort required to produce fracture or metallographic inspection.The weld size is calculated as the average of the maximum dimension and the minimum dimension, which may not always be 90 f
42、rom each other. These measurements are typically made with calipers. Irregularly shaped welds are meas-ured as shown in Figures 9 and 10. All welds must not exceed an aspect ratio of 2 to 1. The tail that might be formed on a button by destructively tearing the two sheets apart shall not be included
43、 in the button measurement.An acceptable weld size is defined by Table 1. As with nugget width, the governing metal thickness (GMT) determines the minimum acceptable weld size unless specified otherwise in the controlling engineering documents. The use of sec-tioning the minimum dimension is to veri
44、fy the accuracy of the destructive evaluation and not intended to classify the weld exclusively.MINIMUMFUSED DIAMETERMINIMUMBUTTON DIAMETERFigure 9Measurement MethodAWS D8.2M:201795.3.2 Fracture Mode. Eight combinations of fracture modes are described in Figures 1118, where their weld quality accept
45、ance criteria are also summarized. When interpretation of weld size is disputed, metallographic inspection must be used to measure nugget width. When determining the nugget width of a weld that has already been destructively tested, the cross section must be taken through the minimum dimension of th
46、e fused area. The purpose of sectioning the minimum dimension is to verify the accuracy of the destructive evaluation and not intended to classify the weld exclusively.5.4 Destructive Inspection Weld Strength CriteriaThe two primary methods to determine the weld strength of individual aluminum spot
47、welds are tensile-shear and cross tension testing (see Figure 19). The mechanical properties to be considered when evaluating weld quality are weld strength and weld fracture energy. Weld mechanical performance of aluminum spot welds may depend upon the loading mode, loading rate, and degree of cons
48、traint. The strength of a weld can be quantified by the peak load achieved during mechanical testing. Weld strength shall be recorded using the test methods described in 5.4.2. While only values for minimum strength are used to describe weld quality in this specification, weld fracture energy values
49、 may be qualitatively considered.Tensile-shear strength is a measure of weld mechanical strength. Welds with strengths below those in Table 2 are consid-ered discrepant. The strength values are applicable to welds between two sheets of the same alloy and gauge. They are applicable to sheet thicknesses between 0.6 mm and 3.6 mm, with weld size assumed to be at minimum per Table 1.5.4.1 Tensile-Shear5.4.1.1 Minimum Tensile-Shear Strength. The minimum tensile-shear strength for various aluminum sheet gauges and material strengths are provided
