scholarly journals High temperature crack initiation and defect assessment of P22 steel weldments using time dependent failure assessment method

2007 ◽  
Vol 74 (6) ◽  
pp. 839-852 ◽  
Author(s):  
B. Dogan ◽  
U. Ceyhan ◽  
B. Petrovski
Keyword(s):  
High Temperature ◽  
Crack Initiation ◽  
Assessment Method ◽  
Time Dependent ◽  
Defect Assessment ◽  
Failure Assessment ◽  
Dependent Failure ◽  
Temperature Crack

Some Fundamental Aspects of High Temperature Defect Assessment

2005 ◽  
Vol 297-300 ◽  
pp. 428-434 ◽  
Author(s):  
Shan Tung Tu ◽  
Fu Zhen Xuan
Keyword(s):  
High Temperature ◽  
Assessment Method ◽  
Damage Effect ◽  
Assessment Procedure ◽  
Continuum Damage ◽  
Creep Failure ◽  
Failure Assessment Diagram ◽  
Defect Assessment ◽  
Failure Assessment ◽  
Dependent Failure

Current research efforts in the development of high temperature defect assessment procedure are summarized. Creep exemption criteria are proposed for the assessment of defective structures at high temperature in consideration of the effects of loadings, operating temperature and service time. Time-dependent failure assessment diagram (TDFAD) is developed that covers major failure mechanisms of defective high temperature structures. Challenges due to the welding effect are discussed. TDFAD for weldments is derived for various combinations of materials. In order to develop a unified assessment method to cope with material and loading complexity, a new failure assessment diagram based on continuum damage concept is proposed to reflect the damage effect on ductile creep failure and brittle creep fracture.

TDFAD Analysis of Creep Crack Initiation in 0.5CMV/2.25CrMoV Steel Weldments

2019 ◽  
Author(s):  
M. Ejaz ◽  
C. M. Davies
Keyword(s):  
Crack Initiation ◽  
Creep Crack Growth ◽  
Compact Tension ◽  
Parent Material ◽  
Time Dependent ◽  
Creep Crack ◽  
Material Condition ◽  
Weld Material ◽  
Failure Assessment ◽  
Dependent Failure

Abstract The time dependent failure assessment diagram (TDFAD) is a convenient methodology to simultaneously assess whether a component is likely to fail by brittle, ductile or creep fracture, plastic collapse or creep rupture. In this work, creep toughness data, Kmatc, have been derived from experimental creep crack growth (CCG) tests on compact tension fracture mechanics specimens made of a weldment consisting of 0.5CMV parent material, 2.25CrMo, where the starter crack was located in the heat affected zone (HAZ). Time dependent failure assessment diagrams (TDFADs) are then constructed for each material condition and creep crack initiation (CCI) time predictions were obtained for the CCG tests performed on the weldment samples using both a TDFAD based on either parent and weld material data. The TDFAD based on the weld data provided the most conservative prediction of CCI times thus is recommended for use for weldment samples.

Integrity Assessment of Defected Structure at High Temperature With a Material Database

2010 ◽  
Author(s):  
Zhengdong Wang ◽  
Fu-Zhen Xuan ◽  
Shan-Tung Tu
Keyword(s):  
High Temperature ◽  
Crack Size ◽  
Pressure Vessels ◽  
Time Dependent ◽  
Integrity Assessment ◽  
Failure Assessment Diagram ◽  
Base Materials ◽  
Axial Tension ◽  
Failure Assessment ◽  
Dependent Failure

The basic theory of Time Dependent Failure Assessment Diagram (TDFAD) is introduced in this paper to be modified for cracks in mismatched welds at high temperature. A time-dependent failure assessment curve is constructed using the method of R6 Option 2. This curve depends not only on the geometry and crack size but also on the mechanical properties of both weld and base materials. The application of such an approach is given to an internal circumferentially defected welded-cylinder under axial tension. An engineering tool of integrity assessment for defected structure at high temperature has been developed for a decade based on the Time Dependent Failure Assessment Diagram (TDFAD) technology for pressure vessels. The software is illustrated in this paper by framework and interfaces and some industrial cases are introduced to show the procedure of the assessment by using the software. A high temperature material database (HTMD) of main properties for typical high temperature steels and alloys is constructed to meet the needs of the safety assessment of the pressure vessels and other structures. The structure of the database is shown in the paper with some tables and charts.

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