On the transfer of specimen J–R curve to piping components with throughwall circumferential flaw

Abstract

A B S T R A C T Transferability of the specimen J-R/J-T curve to the component level is an importantissue in the field of fracture mechanics. Towards this goal, fracture experiments have been carried out on single-edge bend (SE(B)) and compact tension (CT) specimens and throughwall circumferentially cracked straight pipes/elbows of 200 mm nominal bore (NB) diameter. The pipe material is SA 333 Gr 6 steel (low strength and high toughness material) and specimens are machined from the pipes. Subsequently, elastic-plastic finiteelement analyses have been carried out on these cracked components/specimens in order to evaluate the stress triaxiality levels. It is found that the triaxial levels for these cracked components are similar. Hence, similar fracture behaviour is expected for these components. Consequently, one of the pipe J-R curves is used as a reference J-R curve to consider the crack growth in the analysis and the load deformation behaviour of other pipes/elbows is predicted. The load deformation behaviour of the piping components is also predicted using an extrapolated J-R curve from a specimen that exhibits the similar triaxiality level to that of the cracked components. The predicted results are in good agreement with the experiments.Keywords J-R curve; multiaxiality quotient; stress triaxiality; tearing modulus. N O M E N C L A T U R Ea = crack length a 0 = initial crack length b = ligament length B = thickness of the specimen B N = net thickness of the specimen after side grooving E = Young's modulus of elasticity h = stress triaxiality parameter, see Eq.(2) J = J-integral J iC = initiation toughness (J i ) SZW = initiation toughness obtained using ESIS-P2-92 standard J-R = resistance curve J-T = J-integral-tearing modulus approach n = Ramberg-Osgood power exponent Q = Q-stress T = T-stress W = specimen width for SE(B) and CT specimens α = constant in Ramberg-Osgood constitutive equation η = a function to multiply the area under load versus load point deflection curve to get the J-integral Correspondence:

Translating the material fracture resistance into representations in welded tubular structures

“…The current study focuses on the data from small-scale yielding, high-constraint fracture specimens, in deriving the lower-bound J-R curve. The J-R curve data included in the current study covers a wide range of structural steels with various grades for different applications, comprising of the pressure and reactor vessel steels [37][38][39][40][41][42], pipe and pipeline steels [43][44][45][46][47][48], steels for other structural applications [49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65] and weld materials [66,67].…”