Predictions of Cleavage Fracture in Welded Components Incorporating Strength Mismatch Effects: A Weibull Stress Based Approach

2010 ◽  
Author(s):  
Claudio Ruggieri
Keyword(s):  
Cleavage Fracture ◽  
Driving Forces ◽  
Failure Strain ◽  
Pipeline Steel ◽  
Strong Support ◽  
Weld Strength ◽  
J Integral ◽  
X80 Pipeline Steel ◽  
Loading Parameter ◽  
Weibull Stress

This work describes the development of a toughness scaling methodology incorporating the effects of weld strength mismatch on crack-tip driving forces. The approach adopts a nondimensional Weibull stress, σ¯w, as a the near-tip driving force to correlate cleavage fracture across cracked weld configurations with different mismatch conditions even though the loading parameter (measured by the J-integral) may vary widely due to mismatch and constraint variations. Application of the procedure to predict the failure strain for an overmatch girth weld made of an API X80 pipeline steel demonstrates the effectiveness of the micromechanics approach. Overall, the results lend strong support to use a Weibull stress based procedure in defect assessments of structural welds.

A Transferability Model for Cleavage Fracture Toughness in Strength Mismatched Welds Using the Weibull Stress Approach

2010 ◽  
Author(s):  
Claudio Ruggieri
Keyword(s):  
Cleavage Fracture ◽  
Driving Forces ◽  
Failure Strain ◽  
Pipeline Steel ◽  
Strong Support ◽  
Weld Strength ◽  
J Integral ◽  
X80 Pipeline Steel ◽  
Loading Parameter ◽  
Weibull Stress

This work describes the development of a toughness scaling methodology incorporating the effects of weld strength mismatch on crack-tip driving forces. The approach adopts a nondimensional Weibull stress, σw, as a the near-tip driving force to correlate cleavage fracture across cracked weld configurations with different mismatch conditions even though the loading parameter (measured by the J-integral) may vary widely due to mismatch and constraint variations. Application of the procedure to predict the failure strain for an overmatch girth weld made of an API X80 pipeline steel demonstrates the effectiveness of the micromechanics approach. Overall, the results lend strong support to use a Weibull stress based procedure in defect assessments of structural welds.

A Weibull Stress Model to Predict Effects of Weld Strength Mismatch on Cleavage Fracture Toughness

2010 ◽  
Vol 7 (2) ◽  
pp. 102508
Author(s):  
Claudio Ruggieri ◽  
S. Kalluri ◽  
R. M. McGaw ◽  
A. Neimitz ◽  
S. W. Dean
Keyword(s):  
Fracture Toughness ◽  
Cleavage Fracture ◽  
Weld Strength ◽  
Stress Model ◽  
Weibull Stress

A FAD-Based Procedure for Defect Assessments of Welded Structures Including Effects of Weld Strength Mismatch: Micromechanics Approach and Application to Pipeline Girth Welds

2008 ◽  
Author(s):  
Gustavo H. B. Donato ◽  
Claudio Ruggieri
Keyword(s):  
Structural Integrity ◽  
Driving Forces ◽  
Pipeline Steel ◽  
Crack Tip ◽  
Weld Strength ◽  
Homogeneous Material ◽  
Fracture Parameter ◽  
Integrity Assessment ◽  
Girth Welds ◽  
Assessment Problems

ECA procedures of crack-like defects based upon the FAD philosophy have undergone extensive developments in the past decade to form the basis for industrial codes and guidelines for structural integrity assessments. However, the application of these procedures in welded structural components with mismatch in tensile properties between the weld and base metal remains a potential open issue. Weld strength mismatch may significantly alter the crack-tip driving forces, such as J and CTOD, thereby producing crack-tip stresses quite different than the fields that arise in corresponding homogeneous material. Weld strength mismatch also affects the plastic collapse load for the structural component which further complicates the interplay between fracture and plastic instability before gross yield section takes place. This work describes the development of a microme-chanics-based FAD methodology building upon a local fracture parameter, characterized by the Weibull stress (σw), to incorporate the effects of weld strength mismatch on crack-tip driving forces. As a further refinement, the study also addresses an exploratory application of a limit load analysis including effects of weld strength mismatch to correct the loading trajectory incorporated into the FAD procedure. Fracture testing of girth welds obtained from an API X80 pipeline steel provide the data needed to validate the proposed modified FAD procedure in failure predictions. Such an application serves as a prototype for a wide class of integrity assessment problems involving the effects of weld strength mismatch.

Study on Corrosion of X80 Pipeline Steel in Different Water Content of Soil

2014 ◽  
Vol 1015 ◽  
pp. 655-658
Author(s):  
Shu Zhen Yu ◽  
Guang Jun Xu ◽  
Han Hua Song ◽  
Xun Zhu ◽  
Wen We Lu ◽  
...  
Keyword(s):  
Water Content ◽  
High Frequency ◽  
Pipeline Steel ◽  
Electrochemical Corrosion ◽  
High Water ◽  
High Water Content ◽  
Linear Segment ◽  
X80 Pipeline Steel ◽  
The Third ◽  
In The Beginning

The electrochemical corrosion of X80 pipeline steel in Xinzhou’s soil with different water content is tested and analyzed. The corrosion signal time and frequency domain figure show that the corrosion signal fluctuates all the time in 30 days’ test with low water content (14%). The slope of high-frequency linear segment in the potential PSD is smaller than it is at the beginning. In the soil with the middle water content (18%), the intense wave motion lasts for 15 days. The noise fluctuation only exists before the third days when in the high water content soil (22%). After the third day, linear drift can be observed but no transient peak. The slope of high-frequency linear segment changes obviously compared with the situation in the beginning. And the high-frequency white noise appears.

Sign in / Sign up

Export Citation Format

Share Document