




















































































Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community for help and clear up your study doubts
Discover the best universities in your country according to Docsity users
Free resources
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
The measurement of grain size, which is an important characteristic in materials science and engineering. It covers various methods for determining grain size, including the jeffries planimetric method, the heyn/hilliard/abrams intercept method, and the snyder-graff intercept method. The document also discusses the astm standards for grain size measurement, such as astm e112 and astm e930, and the relationship between the astm grain size number and the number of grains per square inch or square millimeter. Additionally, the document covers the history of grain size measurement, the importance of grain shape and topology, and the use of techniques like liquid metal embrittlement and scanning electron microscopy to study actual grain shapes. A comprehensive overview of the topic, making it a valuable resource for students, researchers, and professionals in materials science and engineering.
Typology: Study notes
1 / 92
This page cannot be seen from the preview
Don't miss anything!
Shapes must be space filling
Surfaces must exhibit minimum surface area and minimum surface tension (Plateau, 1873)
Lord Kelvin (1887) showed that the optimum grain shape meeting these requirements was a polyhedron called a tetrakaidecahedra with 14 faces
24 Corners
36 Edges
But, the tetrakaidecahedron does not exhibit 120 dihedral angles between grain boundaries where 3 adjacent grains meet at an edge – unless the faces exhibit curvature.
First to study actual grain shapes by LME of β - brass in liquid Hg. For isolated grains, he found:
Avg. No. Faces/Grain = 14.5 (11 to 20)
Avg. No. Edges/Face = 5.14 (3 to 8) 5-sided grains were most frequent
Used stereomicroradiography to study grains and found:
Avg. No. Edges/Face = 5. Avg. No. Faces/Grain = 12.
For a single polygon, B = 1 and C – E + F = 2
The two- dimensional form of Euler’s Law for an array of polygons is
C – E + F = 1
5/16 Sieve 4 Sieve
8 Sieve
14 Sieve
Separation of grains by sieving after liquid metal embrittlement of Brass in Hg
Actual Grain Shapes
3.3 mm (^) 3.3 mm
3.3 mm
3.3 mm
Types of Grain Sizes
- Non -twinned(ferrite, BCC metals, Al) - Twinned FCC Metals (austenite) - Prior -Austenite (Parent Phase in Q&T Steels)
- Number of Grains/inch^2 at 100X: G - Number of Grains/mm^2 at 1X: NA - Average Grain Area, μm^2 : A **- Average Grain Diameter, μm: d
n = 2 G-
n = number of grains/in^2 at 100X G = ASTM Grain Size Number
Introduced when E 91 – ASTM Method for Estimating the Average Grain Size of Non-Ferrous Metals, Other Than Copper, and Their Alloys – was introduced in 1951. The equation was developed by Timken Co.
Current ASTM Standards for Grain Size
ASTM E 112: For equiaxed, single- phase grain structures
ASTM E 930: For grain structures with an occasional very large grain
ASTM E 1181: For characterizing duplex grain structures
ASTM E 1382: For image analysis measurements of grain size, any type
Other countries established grain size scales using the metric system, based on the number of grains per sq. mm at 1X, NA:
Sweden (SIS 11 11 01); Italy (UNI 3245); Russia (GOST 5639); France (NF A04-102); and ISO (ISO 643) according to: M = 8 (2Gm)
where m = No. Grains/mm^2 at 1X