Session: MF-15-01 Fatigue and Fracture of Welds and Heat Affected Zones

Paper Number: 106163

106163 - Fracture Toughness Estimation of High-Grade Pipeline Steel Girth Weld in Ductile-Brittle Transition Zone 

Estimation of fracture toughness for weld has always been a difficult problem because of the existing of defects and discontinuity of material in weld. In order to investigate the fracture toughness distribution and ductile-brittle transition characteristic of X70 pipeline steel girth weld, fracture toughness curves based on RT_NDT, master curve method, indentation test and convention fracture toughness test were adopted together，and applicability of these methods is studied by comparing with the actual measured fracture toughness values and charpy impact test results. The results show that fracture toughness curves based on RT_NDT have sufficient conservation during the ductile-brittle transition zone and lower bound. The lower envelop curve is more conservative when being higher than DBTT, while revised fracture toughness curve has more conservation when being lower than DBTT. The reference temperature of Master Curve for X70 pipeline steel girth weld by 0.5T SE(B) specimens equals -98 ℃, 1% and 95% cumulative failure probability curves can well envelop the fracture toughness distribution of X70 girth weld, which shows great flexibility in the estimation of fracture toughness of X70 pipeline steel girth weld. Fracture toughness values of ductile mode by instrumented indentation can be used to estimate the DBTT of X70 girth weld.

Presenting Author: Lele Gui CSEI

Presenting Author Biography: Dr GUI works as a senior engineer in China Special Equipement Inspection and Research Institute, and works on the testing of material and strandardaization.

Authors:

Lele Gui CSEI
Tianyu Zhou CSEI
Renyang He CSEI