GB/T 6394-2002 — Metal Average Grain Size Rating Chart
Metallographic Structure Standard Atlas — Metal Average Grain Size Determination Chart GB/T 6394-2002
Series I — Non-Twinned Grains (Light Etching) ×100
Grain size grades ranging from 00 to 8, showing non-twinned austenite grains under light etching at 100× magnification.
Grade 00 – Grade 2
Grade 2½ – Grade 5
Grade 5½ – Grade 8
Series II — Twinned Grains (Light Etching) ×100
Grain size grades 3 through 8, showing twinned austenite grains under light etching at 100× magnification.
Grades 3 – 8
Series IV — Austenite Grains in Steel (Carburizing Method) ×100
Austenite grain size determination using the carburizing method at 100× magnification.
Grade 1 – Grade 6
Grade 7 – Grade 8
Download Original PDF
Click the link below to view or download the original Chinese version of this grain size rating chart:
📥 Download Original PDF — GB/T 6394-2002 Grain Size Rating Chart
Note: This chart follows the Chinese National Standard GB/T 6394-2002 (equivalent to ASTM E112 grain size methodology). Grain size number (G) relates to the average grain area — higher numbers indicate finer grains.
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