ANSI/AWS A4.2M/A4.2:1997 An American National Standard

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1 ANSI/AWS A4.2M/A4.2:1997 An American National Standard Standard Procedures for Calibrating Magnetic Instruments to Measure the Delta Ferrite Content of Austenitic and Duplex Ferritic-Austenitic Stainless Steel Weld Metal

2 Key Words Instrument calibration, delta ferrite, stainless steel weld metal, austenitic stainless weld metal, duplex stainless weld metal ANSI/AWS A4.2M/A4.2:1997 An American National Standard Approved by American National Standards Institute November 6, 1997 Standard Procedures for Calibrating Magnetic Instruments to Measure the Delta Ferrite Content of Austenitic and Duplex Ferritic-Austenitic Stainless Steel Weld Metal Supersedes ANSI/AWS A Prepared by AWS Committee on Filler Metals and The Welding Research Council Subcommittee on Welding Stainless Steels Under the Direction of AWS Technical Activities Committee Approved by AWS Board of Directors Abstract Calibration procedures are specified for a number of commercial instruments that can then provide reproducible measurements of the ferrite content of austenitic stainless steel weld metals. Certain of these instruments can be further calibrated for measurements of the ferrite content of duplex ferritic-austenitic stainless steel weld metals. Calibration with primary standards (nonmagnetic coating thickness standards from the U.S. National Institute of Standards and Technology) is the preferred method for appropriate instruments. Alternatively, these and other instruments can be calibrated with weld-metal-like secondary standards. Reproducibility of measurement after calibration is specified. Problems associated with accurate determination of ferrite content are described. 550 N.W. LeJeune Road, Miami, Florida 33126

3 Table of Contents Personnel... iii Foreword... v List of Tables...vii List of Figures...vii 1. Scope Definitions Delta Ferrite Draw Filing Ferrite Number (FN) Primary Standards Weld-Metal-Like Secondary Standards Calibration Methods Primary Standards Secondary Standards Range of Calibration for All Calibration Methods Calibration of Magne-Gage-Type Instruments Calibration by Means of Primary Standards Calibration by Means of Weld-Metal-Like Secondary Standards Calibration of Feritscopes/Ferritescopes Calibration of Ferritescopes Model FE8-KF by Means of Primary Standards Calibration by Means of Weld-Metal-Like Secondary Standards Calibration of Inspector Gages Calibration by Means of Primary Standards Calibration by Means of Weld-Metal-Like Secondary Standards Calibration of Other Instruments Calibration by Means of Primary Standards Calibration by Means of Weld-Metal-Like Secondary Standards Use of Calibrated Instruments Maintaining Calibration Variations in Measurements Significant Figures in Reporting Measurement Results Calibration Data Measurement Data...12 Annex A1. Acknowledgment...13 A2. Ways of Expressing Ferrite Content...13 A3. Cautions on the Use of Ferrite Number...14 A4. Standards for Instrument Calibration...15 A5. Effect of Ferrite Size, Shape and Orientation...15 A6. Instruments...16 A7. Use of Calibrated Instruments...20 AWS Filler Metal Specifications by Material and Welding Process...23 AWS Filler Metal Specifications and Related Documents...25 vi

4 List of Tables Table 1 Ferrite Numbers (FN) for Primary Standards Calibration of Instruments Using a Magne-Gage No. 3 Magnet or Equivalent Ferrite Numbers (FN) for Primary Standards for Ferritescope Model FE8-KF Calibration Ferrite Numbers (FN) for Primary Standards for Inspector Gage Calibration Maximum Allowable Deviation, Calibration Point to Calibration Curve, for Instruments being Calibrated with Weld-Metal-Like Secondary Standards Tolerance on the Position of Calibration Points Using Primary Standards Maximum Allowable Deviation of the Periodic Ferrite Number (FN) Check for Feritscopes/ Ferritescopes Maximum Allowable Deviation of the Periodic Ferrite Number (FN) Check for Inspector Gages Maximum Allowable Deviation of the Periodic Ferrite Number (FN) Check for Magne-Gage-Type Instruments Expected Range of Variation in Measurements with Calibrated Magne-Gage-Type Instruments Expected Range of Variation in Measurements with Calibrated Feritscopes/Ferritescopes Expected Range of Variation in Measurements with Calibrated Inspector Gages...12 A1 Current NIST Coating Thickness Standards (Nominal Thicknesses) with Approximate Corresponding Ferrite Numbers...16 List of Figures Figure 1 Example of Calibration Lines for Two Magne-Gage Instruments, Each with a No. 3 Magnet for Measuring the Delta Ferrite Content of Weld Metals up to 26 FN Example of Calibration Lines for a Magne-Gage Instrument with a No. 3 Magnet for Measuring the Delta Ferrite Content of Weld Metals up to 77 FN...7 A1 Magne-Gage-Type Instruments...17 A2 Ferritescope Model FE8-KF...19 A3 Inspector Gage...19 A4 Ferrite Indicator (Severn Gage)...20 A5 Foerster Ferrite Content Meter...21 vii

5 A4.2M/A4.2:1997 Standard Procedures for Calibrating Magnetic Instruments to Measure the Delta Ferrite Content of Austenitic and Duplex Ferritic-Austenitic Stainless Steel Weld Metal 1. Scope 1.1 This standard prescribes procedures for the calibration and maintenance of calibration of instruments for measuring, by magnetic attraction or permeability, the delta ferrite content of an austenitic or duplex ferriticaustenitic stainless steel weld metal in terms of its Ferrite Number (FN). 1.2 A thorough review of the Annex is recommended before any instrument is calibrated or used. The Annex presents background information which is essential to understanding the many problems and pitfalls in determining and specifying the ferrite content of weld metals. 1.3 Calibration can be accomplished with the use of the National Institute of Standards and Technology (NIST, formerly National Bureau of Standards) primary standards or weld-metal-like secondary standards. At the present time, only three instruments (Magne-Gage [including a torsion balance using essentially a Magne- Gage No. 3 magnet, hereinafter referred to as a Magne- Gage-type instrument], Ferritescope Model FE8-KF 1, and Inspector Gage) 2 can be calibrated by the use of 1. This is a pre-1980 instrument. Post-1980 models and the current models, now identified as Feritscopes, cannot be easily calibrated with the NIST primary standards and the tables in this document. See Section These instruments were selected for testing from several similar instruments by the Welding Research Council s Subcommittee on Stainless Steel Welding. Each instrument was extensively tested to develop the data shown in Tables 1, 2, and 3. This standard contains those data and instructions for their use. For information or requests regarding the ability of other instruments to be calibrated to NIST Primary Standards, contact the Welding Research Council, 345 East 47th Street, New York, NY NIST primary standards and the values in Tables 1, 2, or 3 in this document. The range of possible calibration depends upon the particular instrument. This is not an endorsement of any particular instrument (see 3.1). 1.4 Some manufacturers may not calibrate their instruments to A4.2. Therefore, if calibration to A4.2 is required, it is the responsibility of the user of the instrument that this calibration be performed. 2. Definitions Delta Ferrite. The ferrite which remains at room temperature from that which was formed from the molten state upon freezing. Much of the original ferrite that formed upon freezing transforms to austenite during cooling. 2.2 Draw Filing. This weld pad surface preparation technique is suitable for subsequent ferrite measurements up to about 20 FN (see 8.2). A sharp, clean 350-mm [14-in.] mill bastard file, which has not been contaminated by ferromagnetic materials, held parallel to the base metal and perpendicular to the long axis of the weld metal sample, is stroked smoothly with a firm, downward pressure, in the forward (cutting) direction only, along the weld length. No cross-filing is done. The finished surface is flat with at least a 3-mm [1/8-in.] width where all weld ripples are removed. 3. For AWS terms and definitions, refer to the latest edition of ANSI/AWS A3.0, Standard Welding Terms and Definitions. Please note that some of the terms and definitions used in this publication are not included in AWS A3.0. They are either new terms defined after the latest revision of A3.0 or they are used specific to this publication. 1

AWS A4.2M:2006 (ISO 8249:2000 MOD) An American National Standard

AWS A4.2M:2006 (ISO 8249:2000 MOD) An American National Standard An American National Standard Standard Procedures for Calibrating Magnetic Instruments to Measure the Delta Ferrite Content of Austenitic and Duplex Ferritic-Austenitic Stainless Steel Weld Metal Key Words