What is ISO 643 about?

ISO 643 specifies a micrographic method of determining apparent ferritic or austenitic grain size in steels.

ISO 643 describes the methods of revealing grain boundaries and of estimating the mean grain size of specimens with unimodal size distribution. ISO 643 provides a technical specifications on revealing ferritic grain boundaries, revealing austenitic and prior-austenitic grain boundaries and other methods for revealing prior-austenitic grain boundaries.

Who is ISO 643 for?

ISO 643 on the micrographic determination of grain size in steels is applicable to:

Manufacturers of steel and steel components
Suppliers and dealers of steel and steel components
Quality control personnel

Why should you use ISO 643?

Grains are three-dimensional in shape, the metallographic sectioning plane can cut through a grain at any point from a grain corner to produce a range of apparent grain sizes on the two-dimensional plane. Determination of grain size is used for quality assessment purposes.

ISO 643 provides you guidance on the principle, selection and preparation of specimens for the test method. ISO 643 also helps you to characterize grain size and provides an evaluation method to determine the grain size in steel. This enables you to improve the physical properties of steel such as strength and toughness.

ISO 643 guidelines enable you to determine ferritic and austenitic grain size in steels to produce high corrosion-resistant steel products.

What’s changed since the last update?

BS EN ISO 643:2020 supersedes BS EN ISO 643:2012, which is now withdrawn.

Changes in BS EN ISO 643:2020 include –

7.1.2 has been modified
The original Annex B has been deleted and the original Annex C has been renumbered as Annex B
Minus sign replaced with a plus sign between the values in Formula B.9

BS EN ISO 643:2020

Steels. Micrographic determination of the apparent grain size

Published:

31 May 2020

Withdrawn:

6 Sep 2024