ASTM B645-21 PDF

Full title and description

ASTM B645-21 — Standard Practice for Linear-Elastic Plane-Strain Fracture Toughness Testing of Aluminum Alloys. This practice provides supplementary guidance for applying Test Method E399 to aluminum alloys, with emphasis on specimen sampling, specimen-size selection, and interpretation of test results when full plane‑strain validity requirements cannot be met for lot-release and quality‑assurance purposes.

Abstract

ASTM B645-21 supplements Test Method E399 by giving consistent procedures for dealing with routine quality-assurance fracture toughness testing of aluminum alloys when the strict requirements for valid plane‑strain fracture toughness measurements are not achievable. The practice addresses specimen selection and placement, recommended specimen sizes (C(T) specimens only), interpretation of invalid KIC/KQ results for lot release, and related reporting considerations to support material qualification and release decisions.

General information

• Status: Published
• Publication date: Approved Dec 1, 2021; published January 2022
• Publisher: ASTM International
• ICS / categories: 77.120.10 (Aluminium and aluminium alloys)
• Edition / version: B645-21
• Number of pages: 6

Scope

This practice is applicable to fracture‑toughness testing of all aluminum alloys, tempers, and product forms where tests are used to determine whether individual lots meet specification requirements for release. It is intended as a supplement to Test Method E399 and covers specimen sampling, specimen size selection (current practice accommodates compact‑tension (C(T)) specimens), and interpretation of invalid plane‑strain fracture‑toughness results for quality‑assurance and lot‑release decisions.

Key topics and requirements

• Supplemental practice to ASTM E399 for aluminum alloys.
• Guidance on specimen sampling locations and orientation within product cross sections (plate, forgings, extrusions, rod).
• Recommendations for specimen size selection and minimum dimensions, focused on C(T) specimens.
• Procedures for interpreting and using invalid plane‑strain fracture‑toughness (K) test results for lot‑release and QA when valid KIC cannot be obtained.
• Use of SI units as the standard; inch‑pound values provided for information only.
• References to related ASTM methods and terminology (for example, E399, E1823, B646, E29, E561).

Typical use and users

Materials testing laboratories, OEM and supplier quality engineers, metallurgists, and spec writers in industries that use aluminum (aerospace, defense, transportation, and general manufacturing) use this practice as a tool for routine fracture‑toughness quality assurance, lot release decisions, and interpretation of test data when full plane‑strain validity is not obtainable.

Related standards

Key related standards referenced in the practice include ASTM E399 (Test Method for Linear‑Elastic Plane‑Strain Fracture Toughness of Metallic Materials), ASTM E1823 (Terminology Relating to Fatigue and Fracture Testing), ASTM B646 (Practice for Fracture Toughness Testing of Aluminum Alloys), ASTM E561 (K‑curve determination), and ASTM E29 (use of significant digits).

Keywords

aluminum alloys, fracture toughness, plane‑strain, linear‑elastic, C(T) specimen, KIC, invalid K, quality assurance, lot release, specimen sampling, ASTM B645

FAQ

Q: What is this standard?

A: ASTM B645-21 is a practice that supplements ASTM E399 by providing guidance for linear‑elastic plane‑strain fracture‑toughness testing of aluminum alloys, specifically for quality‑assurance and lot‑release situations where full plane‑strain validity may not be achievable.

Q: What does it cover?

A: It covers specimen sampling and placement in product cross sections, specimen‑size selection (written to accommodate C(T) specimens), interpretation of invalid fracture‑toughness results for material release, and reporting conventions—using SI units as the standard.

Q: Who typically uses it?

A: Test laboratories, quality and materials engineers, suppliers and manufacturers of aluminum products, and organizations (including defense and aerospace) that require consistent approaches to fracture‑toughness QA and lot release.

Q: Is it current or superseded?

A: B645-21 is the current edition (approved Dec 1, 2021; published January 2022) and supersedes the prior reapproved edition B645‑10 (2015). It remains the active practice for the subject matter at the time of publication.

Q: Is it part of a series?

A: It is part of the suite of ASTM standards addressing fracture toughness and testing of light metals, intended to be used alongside E399 and related test methods and practices rather than as a standalone test method.

Q: What are the key keywords?

A: Aluminum alloys; fracture toughness; plane‑strain; linear‑elastic; C(T) specimen; KIC; quality assurance; lot release; specimen sampling.