AWS A4.2M/A4.2

X-REF BY AWS A4.2M * PHOTOCOPY

This standard prescribes procedures for the calibration and maintenanceof calibration of instruments for measuring, by magnetic attraction orpermeability, the delta ferrite content of an austenitic or duplexferritic-austenitic stainless steel weld metal in terms of its FerriteNumber (FN).

A thorough review of the Annex is recommended before any instrument iscalibrated or used.The Annex presents background information which isessential to understanding the many problems and pitfalls in determiningand specifying the ferrite content of weld metals.

Calibration can be accomplished with the use of the National Instituteof Standards and Technology (NIST, formerly National Bureau ofStandards) primary standards or weld-metal-like secondary standards.Atthe present time, only three instruments (Magne-Gage [including atorsion balance using essentially a Magne-Gage No. 3 magnet, hereinafterreferred to as a Magne-Gage-type instrument], Feritscope Model FE8-KF(Footnote 1), and Inspector Gage) (Footnote 2) can be calibrated by theuse of NIST primary standards and the values in Tables 1, 2, or 3 inthis document.The range of possible calibration depends upon theparticular instrument.This is not an endorsement of any particularinstrument (see 3.1).

Some manufacturers may not calibrate their instruments to A4.2. Therefore, if calibration to A4.2 is required, it is the responsibilityof the user of the instrument that this calibration be performed.

Footnote 1 – This is a pre-1980 instrument.Post-1980 models and thecurrent models, now identified as Feritscopes, cannot be easilycalibrated with the NIST primary standards and the tables in thisdocument.See Section 5.

Footnote 2 – These instruments were selected for testing from severalsimilar instruments by the Welding Research Council's Subcommittee onStainless Steel Welding.Each instrument was extensively tested todevelop the data shown in Tables 1, 2, and 3.This standard containsthose data and instructions for their use.For information or requestsregarding the ability of other instruments to be calibrated to NISTPrimary Standards, contact the Welding Research Council, 345 East 47th

Edition:

97

Published:

01/01/1997

ANSI:

ANSI Approved

Number of Pages:

31