This publication is an extract of AWS B2.1@ Specification for Welding Procedure and Performance Qualification@ and is identical to Annex IV@ Base Metal Grouping@ in the 2005 edition of that standard. This publication may be referred to by other codes and standards that have welding procedure and performance requirements in order to avoid duplication of materials tables in those publications. Base metals and filler metals have been grouped into categories that will minimize the number of qualification tests required. Substitution of one base metal or filler metal for another@ even when within the allowable rules@ should only be made after an evaluation of the factors involved. For some materials@ additional tests may be required. Materials not listed require separate qualification.