GB/T 13320-2025Metallographic grading atlas and assessment method for steel die forgings (English PDF)

3 Terms and definitions

4 Grouping and grading of the rating charts

5 Application of the rating charts

6 Preparation of the test specimens

7 Assessment of the metallographic structure

Foreword

This document was issued on 31 December 2025 by the State Administration for Market Regulation and the Standardization Administration of the People's Republic of China, and has been in force since 1 July 2026.

It replaces GB/T 13320-2007.

The document is under the responsibility of the Standardization Administration of China.

Classification: ICS 77.140.85, CCS J 32.

3 Classification and status

GB/T 13320-2025 is classified under ICS 77.140.85, in the field of metallurgy. ICS is the International Classification for Standards, the same scheme used by ISO and by the national bodies of most countries, which is what allows a Chinese standard to be placed beside its foreign counterparts on subject rather than on number.

Its Chinese Standard Classification code is CCS J 32. CCS is the domestic scheme, a letter for the sector and two digits for the subject within it, and it is the code by which the standard is filed and searched in China.

The GB/T prefix marks a recommended national standard. It is not, in itself, law: it becomes binding when a contract names it, when a regulation or a mandatory standard refers to it, or when a producer declares conformity with it. In practice that covers most of the cases in which it will be read — a purchase specification, an inspection agreement or a certification scheme.

The document is under the responsibility of the Standardization Administration of China, which is the body that maintains it and that will answer a formal question about its interpretation.