Role of constraint on the shift of ductile-brittle transition temperature of subsize Charpy specimens ORIGINAL CONTRIBUTION

• Published in: Fatigue & fracture of engineering materials & structures 2014-05
• Main Authors: Capelle, Julien, Amara, M Ben, Pluvinage, G, Azari, Z
• Format: Article
• Language: English
• Subjects: Engineering Sciences; Materials and structures in mechanics; Mechanical engineering; Mechanics; Mechanics of materials
• ISSN: 8756-758X; 1460-2695
• DOI: 10.1111/ffe.12212

The ductile-brittle transition temperature is not intrinsic to steel but depends on the specimen type and loading mode used for the test. The influence of these parameters is related to the plastic constraint. Here, the constraint is evaluated by the effective T-stress obtained by the stress difference method on the notch tip stress distribution. From Charpy energy values at different temperatures, it is possible to obtain a material failure master curve where the notch fracture toughness is plotted versus the shift of test temperature with the transition temperature corresponding to the effective T-stress value. Values of the critical effective T-stress are obtained for three subsize Charpy specimens (3/4, 1/2 and 1/3) and are reported on a material transition temperature master curve versus effective T-stress. This allows obtaining the shift of transition temperature when comparing with those of a standard Charpy V specimen. The results do not confirm the prediction given by the empirical relation of the ASME. Keywords constraint; material failure master curve; subsize Charpy specimen; transition temperature; T-stress. N O M E N C L A T U R E a = notch depth A = constant A CV = constant A J,ρ = constant A % = elongation at failure b = ligament size B = constant B* = thickness B std = thickness for standard Charpy specimen B ss = thickness for subsize Charpy specimen B J,ρ = constant B CV = constant C = constant C* = compliance C CV = constant C j,ρ = constant D = constant D CV = constant D J,ρ = constant E = Young's modulus J = J integral J ρ,c = notch fracture toughness J ρ,c K CV = Charpy energy K CV,sd = energy for standard Charpy specimen K CV,ss = energy for subsize Charpy specimen