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ASTM Selected Technical Papers
Charpy Impact Test: Factors and Variables
By
JM Holt
JM Holt
1
Alpha Consultants & Engineering
?
1504 Williamsburg Place Pittsburgh, PA 15235-4924
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ISBN-10:
0-8031-1295-5
ISBN:
978-0-8031-1295-7
No. of Pages:
226
Publisher:
ASTM International
Publication date:
1990

The effect of preparing the notches for Charpy V-Notch impact specimens is evaluated. Two methods of preparation are used for this evaluation. They are grinding and broaching. Impact specimens with two energy levels were used: low energy, 15 J (11 ft∙lbf) and high energy, 94 J (69 ft∙lbf). Twenty-four specimens of each level were made with ground notches and with broached notches. Each was tested with a calibrated impact tester. The material used for the specimens was AISI-4340 alloy steel. The notch characteristics were documented by the following methods: notch angles, notch radii, surface conditions, and near-surface microstructure. Other parameters documented for this study were the ligament thickness, specimen width, and specimen length. In addition, test conditions and results are provided as follows: test temperature, absorbed energy, and lateral expansion. Besides tabular data, photographs give views of the notch surface. Evaluation of the results indicated both types of notches gave equally consistent values, but the ground and broached values differed in their averages. Possible causes for this variation were differences in ligament sizes and bottom of notch radii, surface tears and shallow microstructural deformation in the case of the broached notches.

1.
Driscoll
D.E.
, “
Reproducibility of Charpy Impact Test
,” Symposium on Impact Testing, ASTM STP 176,
American Society of Testing and Materials
,
1955
, p. 170.
2.
Fahey
N.H.
, “
Effects of Variables in Charpy Impact Testing
,”
Materials Research & Standards
, Vol.
1
, No.
11
,
11
1961
, page 872.
3.
ASTM Standard E 23, “
Standard Methods for Notched Bar Impact Testing of Metallic Materials
,” 1988 Annual Book of ASTM Standards, Vol.
03.01
, Metals-Mechanical Testing; Elevated and Low-Temperature Tests; Metallography, by
American Society for Testing and Materials
,
Philadelphia
,
1988
, p. 191.
4.
ASTM Standard E 3-80 (Reapproved 1986), “
Standard Methods of Preparation of Metallographic Specimens
,” , p. 74.
5.
ASTM Standard E 407-70 (Reapproved 1982), “
Standard Methods for Microetching Metals and Alloys
,” , p. 505.
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