INVESTIGATIONS IN FRACTURE-MECHANICS FAILURE CONCEPTS WITH THERMOMECHANICALLY ROLLED STEELS

Thermomechanically rolled steels of quality StE-480 TM and a conventional mild steel (St 52-3) were investigated in instrumented Charpy impact tests, fracture mechanics tests, tension tests with fatigue precracked specimens and wide plate tests with notched specimens (CNT or DENT) up to a maximum load of 4 MN. Several specimens were welded. The results were used for determining various transition temperatures and for checking several actual safety concepts of linear elastic and elastic-plastic fracture mechanics, namely the K(I)-concept, two methods basing on CTOD (CTOD design curve and PD 6493), and two methods using J-integral (EPRI and R6). Of these methods the new version of the R6 methods seems most promising. J-integral values of wide plates calculated with various finite element programs agreed rather well with one another and with experimental results.