FCTM Esope

S2.12 - Fracture mechanical investigations on large scale tensile tests of high strength pressure vessel base material and welding joints

Oct 7, 2021 | 2:00 PM - 2:30 PM

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The construction of pressure vessels is currently dominated by normal-strength steels due to the material side. According to EN 13445, the use of high-strength steels with a yield strength higher than 500 MPa is subject to high regulatory requirements. As a result, high-strength steels are only used in individual cases in pressure vessel construction. The current standardization for the use of high-strength steels in pressure vessel construction has to be improved by enabling brittle fracture detection on the basis of simple design rules instead of the currently necessary complex fracture mechanical analysis. Thus, high-strength steels are less disadvantaged by lower safety coefficients. In order to quantify the toughness properties of high-strength steels, investigations were performed out on a quenched and tempered steel of grade P690QL which is suitable for use in pressure vessel construction. Large tensile tests were carried out on this steel on flat tensile specimens of similar thickness and varying test temperature. A DECT specimen geometry (Double Edge Crack Tension) was used. In addition, the same tests were also tested on welded specimens. The focus was on the heat-affected zone. The toughness requirements of the steel were then determined numerically using the finite element method. For this purpose, the experimental large-scale tensile tests were converted into a numerical model and simulated in accordance with the experimental test procedure. It could be shown that despite the higher requirements at a temperature of 100 °C, the investigated steel of the grade P690QL has a high toughness level.

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