Part 1: Specimen Thickness Effects for Elastic-Plastic CTOD Toughness of an A36 Steel
This paper describes the results of an experimental and analytical study of the effect of specimen size on the fracture-toughness behavior of A36 steel, primarily in the lower-transition region. This region is beyond the limits of plane-strain as defined by ASTM E-399, but in the region where failure occurs prior to any macroscopic fibrous tearing. Experimental results were obtained using Crack-Tip Opening Displacement (CTOD) three-point bend specimens, and analytical results were obtained using a 3-D elastic-plastic finite-element analysis. Two specimen sizes, full thickness [31.8-mm (1.25-in.) thick] and reduced thickness [12.7-mm (0.50-in.) thick], were investigated using the preferred t X 2t X 8t specimen size.
Part 2: An Analytical and Experimental Comparison of Rectangular and Square CTOD Fracture Specimens of an A36 Steel
Analytical and experimental investigations of both the rectangular cross-section (t * 2t) and square crosssection (t * t) three-point bend CTOD fracture specimens were conducted on an A36 steel. This study is part of a long-range investigation aimed at developing criteria to evaluate the susceptibility to fracture in specific structural situations, i.e., pressure vessels and structural steels with short cracks (a/W≃ 0.15), where the square CTOD specimen must be used. Generally the rectangular CTOD specimen is used in laboratory testing, but for weldment testing where shallow surface cracks may exist or for other structural applications with crack depth ratios other than a/W≃0.5, the square specimen is often required. The objective of this study was to compare the CTOD fracture toughness results of square specimens with those of rectangular specimens using equivalent crack depth ratios (a/W = 0.5). The next phase of this long-range investigation will study the fracture behavior of specimens with shallow cracks (a/W ≃ 0.15).
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| Number of Pages : | 30 |
| Published : | 1987 |
