Abstract
Four methods for determining JIC value using small specimens are compared on A533B Cl. 1 steel (HSST 03 Plate). Three-point bend tests are carried out at temperatures between-65 and 70°C. The crack initiation point on a load-deflection curve is determined by an electrical potential method. Besides this, precracked Charpy type specimens of A533B Cl. 1 and A542 steels are tested using the R-curve method to clarify the relation between the J integral value and COD value. The test results obtained are as follows:
(1) The method proposed by RICE is the most useful with respect to its simplicity, accuracy, and requirement of only one specimen.
(2) The specimen size requirement for a valid JIC value can be described by the following equation; B≥25 (J/δY) where B is the specimen thickness and δY is the yield strength.
(3) The empirical results obtained with small specimens are in good agreement with those obtained with large ones.
(4) The blunting line used in the R-curve method can be described by the following equation; J=3.7δYΔa where δY is the yield strength and Δa is the crack extension.
(5) J value, COD, and lateral contraction, LC are related with each other as follows; J/σY=2.6 (COD) J/σY=2.0 (LC) COD=0.77 (LC)
