Grain Size (ASTM E112 Number)
Engineering definition, metallurgical mechanisms, standard testing specifications, and manufacturing guidelines for closed-die forgings up to 50 kg.
Quick AnswerFeatured
The standardized numerical ranking (from 1 to 10+) of the average crystal size in a polycrystalline metal, where higher numbers represent finer grains.
Technical Explanation & Metallurgical Principles
Per the Hall-Petch relationship, finer grain sizes simultaneously improve yield strength and impact toughness. ASTM Grain Size No. 5 or finer (fine austenitic grain practice) is mandatory for low-temperature carbon steels (ASTM A350 LF2) and high-yield pipeline flanges.
Key Engineering Specifications & Parameters
| Technical Parameter / Metric | Engineering Benchmark / Value |
|---|---|
| Standard Ranking | ASTM No. 5 to 8 considered 'Fine Grain' |
| Formula | N = 2^(n-1) where N is grains/in² at 100x magnification |
Application at Jayesh Forge (Rajkot Plant)
Verified microscopically at 100x on metallographic sample mounts at our Rajkot laboratory for all normalized and Q&T forgings.
Related Materials, Standards & Products
Related Metallurgical & Testing Terms
Normalizing Heat Treatment
A heat treatment process where steel is heated 40°C to 60°C above its upper critical transformation temperature (Ac3), soaked, and cooled in still air.
Charpy V-Notch Impact Test (CVN)
A standardized dynamic test that measures the kinetic energy absorbed by a notched 10x10mm specimen when fractured by a swinging pendulum hammer at specified temperatures.
Ductile-to-Brittle Transition Temperature (DBTT)
The critical temperature threshold below which a body-centered cubic (BCC) metal loses its plastic ductility and fractures in a sudden, brittle cleavage manner.
Questions Regarding Grain Size (ASTM E112 Number)
A greater density of grain boundaries forces advancing cleavage micro-cracks to repeatedly change direction, consuming crack energy and preventing rapid brittle failure.
Request a Forging Quote with Grain Size (ASTM E112 Number) Compliance
Our Rajkot metallurgy desk is ready to review your technical drawings, testing protocols, and delivery schedules for custom closed-die forgings strictly up to 50 kg.