A test program was conducted to determine the effects of specimen thickness variations, side grooves, and crack length variations on the deformation and ductile fracture of A533-B, Cl-1 steel at 93°C.
The crack extensions were estimated using the correlation between elastic compliance and crack length. Crack extensions were also estimated using a correlation among crack-opening displacements, load line displacements (δ - VL), and crack length. The inferred estimates of crack extension were supplemented by some measurements on heat-tinted fracture surfaces. The results suggest that the observation of thickness or side-groove effects on crack-extension resistance curves is dependent on the method of measuring crack extension.
The compliance correlation method was less sensitive to crack extension and showed a classical thickness effect: increased crack growth resistance with decreasing thickness, and decreased resistance with the use of side grooves. The δ - VL correlation method was more sensitive to crack extension and showed no effect of thickness or of side grooves on crack growth resistance. The presence of side grooves promoted flat fracture and suppressed shear lips. Specimens without side grooves developed large shear lips.