Numéro : 2750 - Year : 2020
Charpy V tests - Risks linked to the tests with 3 samples
Michel HUTHER - Vice-Président ATMA - Paris (France)
Henri-Paul LIEURADE - Président CCRS Fatigue – Paris (France)
To verify the non brittleness of a steel component during service it is generally performed Charpy tests with 3 samples. The works performed since a large number of years in welded joints fatigue applying probabilities and statistics have shown that, to have a good evaluation of the minimum resistance, it is cleary necessary to have a larger number of test results.
In view to analyse the risk attached to this practice of 3 samples it has been selected a test result series of 17 values of Charpy V on a same steel plate. From this series, by translation, it has been generated 2 series, first with one 3 samples test giving a acceptable steel and secondly with one 3 samples test giving a non acceptable steel.
The method of verification with 3 samples has been applied to these series leading to a possible number of 12 tests each. It has been so observed that the testing with 3 samples leads to a risk of error of some 30 to 40%. It has also been observed that the determination of the transition curve of a DH36 steel shows that the temperature for a CV of 27J is about -50°C when the rules require only ‑20°C.
In conclusion it is given a possibility of improvement of the test procedure which is the subject of study within the scope of the "CCRS rupture et fatigue" of the SF2M.
Advanced search
Year