Preliminary Study of Testing Specimen Thickness Effect on Fracture Toughness for X70 Steel

Abstract:

The influences of testing specimen thickness (TST) on fracture toughness, including drop weight tear test shear area (DWTT) and crack tip opening distance (CTOD), are studied by experimental method for X70 steel. Results show that DWTT and CTOD reduce gradually with the specimen thickness increasing, showing an apparent TST effect. DWTT results also show that the TST effect is more significant at the middle transition temperature range. Parameters including J-integral, constraint parameters (T₃₃&T_z) and plastic volume ratio (V_r) of SENB specimens with different thickness are calculated by FEA method. Then the TST effect correlation of |T₃₃|, T_z and V_r are compared. All parameters show a strong thickness dependent. Crack tip constraint parameters, |T₃₃| and T_z, have a similar variation tendency, but different from that of J. Contrary, V_r has a more similar variation tendency with J. Therefore, plastic deformation behavior cannot be ignored during studying the TST effect of X70 steel. V_r can be treated as an alternate parameter to explain TST effect.

• Periodical: Key Engineering Materials (Volume 744)
• Pages: 264-269
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.744.264
• Online since: July 2017
• Authors: Qi Lou, Wei Du*
• Keywords: Fracture Toughness, T₃₃, Testing Specimen Thickness Effect, T_z, X70 Steel

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