SYMPOSIA PAPER Published: 01 January 1965

Fracture Testing of Weldments


A new and improved apparatus has been designed and built for three-point loading of bend bars. A new formula for KIc independent of Young's modulus has been derived which fits experimental calibrations and calculations by B. Gross with satisfactory accuracy. A formula is provided by which the requirements for specimen size and notch depth can be calculated for measuring KIc for a given yield strength of material. A number of comparisors are shown for the effect of rolling direction on KIc for base plate and for several different kinds of welding. The effect of notch position on KIc is shown. The slow bend test has advantages of adaptability and simplicity for the purpose at hand.

It seems noteworthy that the effect of directionality on KIc in the base plate is in the same direction but magnified in tests of the welds in the 250-ksi yield-strength grade. For some welding procedures the KIc for some positions in welds was better than for the base plate with no deficiency of hardness. Significance tests were applied to the differences between average values of KIc. From the KIc numbers listed one may calculate the largest tolerable surface crack corresponding to a given stress applied. The center of the weld presents the lowest toughness of any position.

Author Information

Kies, JA
U.S. Naval Research Laboratory, Washington, D.C>
Smith, HL
U.S. Naval Research Laboratory, Washington, D.C>
Romine, HE
Warhead and Terminal Ballistics Lab., U.S. Naval Weapons Laboratory, Dahlgren, Va.
Bernstein, H
Special Projects Office, Bureau of Weapons, Washington, D.C.
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Developed by Committee: E08
Pages: 328–356
DOI: 10.1520/STP26599S
ISBN-EB: 978-0-8031-4569-6
ISBN-13: 978-0-8031-0105-0