On fracture toughness and its size dependence for steels showing thickness delamination
✍ Scribed by Karl Markström
- Publisher
- Elsevier Science
- Year
- 1972
- Tongue
- English
- Weight
- 759 KB
- Volume
- 4
- Category
- Article
- ISSN
- 0013-7944
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✦ Synopsis
The effect of thickness delamination on fracture toughness has been studied. The test material used was a martensitic-austenitic pressure vessel steel. Tests were performed on compact tension and three point bend specimens ofvarying sizes. All specimens were machined from plate material of 100 mm thickness. it was found that the ASTM practice of test evaluation leads to a size dependence of fracture toughness although data for all specimens fulfill the ASTM size requirements. This size dependence has been explained theoretically and it was shown that an evaluation method based on a fixed absolute amount of apparent crack extension would lead to coinciding data for all specimen sizes.
NOTATION
crack lengt,t specimen thickness crack opening displacement measured at specimen surface mode I stress intensity factor plane strain fracture toughness provisional fracture toughness value according to ASTM secant fracture toughness value according to ASTM modified fracture toughness value charpy V-notch impact energy applied load formal plastic zone radius loading span total relative deviation from linearity in the test record relative deviation from linearity in the test record due to plastic effects specimen width ratio of deviation from linearity at loads corresponding to K, and @8 K,s, respectively elongation of tensile specimen ultimate tensile strength 0.2 per cent offset yield strength, 593