Creep Crack Growth in High-Temperature Impure Helium Environments

2014 ◽  
pp. 203-209
Author(s):  
D. Grierson ◽  
G. Cao ◽  
A. Glaudell ◽  
D. Kuettel ◽  
G. Fisher ◽  
...  
Keyword(s):  
High Temperature ◽  
Crack Growth ◽  
Creep Crack Growth ◽  
Creep Crack

Assessment of Power Plant Components With Flaws and Defects Operating in the Long-Term Creep Range

2019 ◽  
Author(s):  
Magdalena Speicher ◽  
Thorben Bender ◽  
Andreas Klenk ◽  
Falk Mueller ◽  
Christian Kontermann ◽  
...  
Keyword(s):  
High Temperature ◽  
Fracture Mechanics ◽  
Crack Initiation ◽  
Crack Growth ◽  
Creep Crack Growth ◽  
Material Behavior ◽  
Critical Crack Length ◽  
Creep Crack ◽  
Combining Data ◽  
Crack Problems

Abstract Originating from defects and flaws in high temperature components crack initiation and crack propagation under service conditions can occur. Fracture mechanics data and procedures are needed to study crack problems and to support an advanced remnant life evaluation. During subsequent research in the past 35 years, data were determined for different high temperature materials. Methodologies and concepts taking into account the specific material behavior were developed in order to be able to describe crack initiation and crack growth and have appropriate assessment methods available. For creep crack initiation two criteria principles were used and for creep crack growth assessment based on the integral C* parameter were applied. Furthermore, a method for determination of critical crack length was developed allowing decisions whether modified stress analysis methods are sufficient or more complicated fracture mechanics methods are needed. To provide data and methodologies in a user-friendly way, a program system combining data and methods was implemented. The paper describes developed features and shows comparisons to other methods. The methods can be applied for design purposes as well as remnant life assessments.

The Influence of Creep-Fatigue Interaction on High Temperature Crack Growth in 316 Steel Weldments

2009 ◽  
Author(s):  
C. M. Davies ◽  
David W. Dean ◽  
A. N. Mehmanparast ◽  
K. M. Nikbin
Keyword(s):  
High Temperature ◽  
Crack Growth ◽  
Static Load ◽  
Growth Models ◽  
Creep Crack Growth ◽  
Crack Tip ◽  
Parent Material ◽  
Creep Crack ◽  
Static Creep ◽  
Temperature Crack

High temperature crack growth in weldments is of great concern and generally occurs along the boundary between the heat affected zone (HAZ) and parent material (PM) of welded components in high temperature plants. Static creep and low frequency cyclic crack growth tests have been performed on compact tension, C(T), specimens manufactured from sections taken from a 316 steel weldment at 550 °C, where the crack tip was located along the fusion line within the HAZ. The data has been analyzed in terms of both the creep-brittle and creep-ductile crack tip parameters, K and C*, respectively. The cyclic test results have been compared to static creep crack growth tests on 316 steel weldments and homogeneous parent material specimens, and to crack growth models. The cracking rates of the cyclic crack growth tests are found to be higher than that of the of the static load creep crack growth tests on weldments. The data may be bounded by the high frequency fatigue and the static load creep crack growth predictions. However, further work is required to establish the fatigue and subsequently the creep component of the cyclic load crack growth tests on weldments.

Effects of Temperature Changes on Creep Crack Growth for a Low Alloy Butt Weld

2013 ◽  
Author(s):  
Jinhua Shi
Keyword(s):  
High Temperature ◽  
Residual Stresses ◽  
Crack Growth ◽  
Creep Crack Growth ◽  
Welding Residual Stress ◽  
Assessment Procedure ◽  
Butt Weld ◽  
Temperature Changes ◽  
Creep Crack ◽  
Effects Of Temperature

R5 is an assessment procedure for the high temperature response of structures and R5 Volume 7 specifies the creep crack growth assessment for low alloy welds. For high temperature low alloy butt welds, the effects of the welding residual stresses on the creep crack growth for a circumferential defect has been investigated by Shi under a constant temperature of 532.7°C. In addition to the welding residual stresses, it is well known that temperatures also affect significantly creep deformation, creep rupture and accordingly creep crack growth. Hence, in this paper an investigation for the effects of temperature changes on the creep crack growth and also on component remnant lives has been carried out. In this paper, for a typical low alloy butt weld in ½Cr½Mo¼V (‘½CMV’) pipework with 2¼Cr weld metal under a given internal pressure and a bending welding residual stress of 60MPa, a series of creep crack growth analyses have been conducted using the R5 Volume 7 assessment procedure, assuming different operating temperatures during different operating periods. A postulated internal circumferential defect (semi-elliptical surface-breaking surface defect) of 2.3 mm deep by 15 mm long has been used. The investigation results are presented by a series of graphs which show the effects of the temperature changes on the creep crack growth and plant remnant lives for the weld studied. After a detailed discussion, conclusions can be drawn.

Specimen Geometry Effects on Creep Crack Initiation and Growth in Parent Materials and Weldments

2011 ◽  
Author(s):  
Catrin M. Davies ◽  
Robert C. Wimpory ◽  
David W. Dean ◽  
Kamran M. Nikbin
Keyword(s):  
High Temperature ◽  
Crack Initiation ◽  
Crack Growth ◽  
Creep Crack Growth ◽  
Parent Material ◽  
Crack Growth Behaviour ◽  
Creep Crack ◽  
Significant Difference ◽  
Constraint Effects

High temperature crack growth in weldments is of great practical concern in high temperature plant components. Cracking typically occurs in the heat affected zone (HAZ) and often propagates into adjacent parent material (PM). Recently, the importance of constraint effects on creep crack growth behaviour has been recognised and creep crack growth testing on a range of specimen geometries has been performed. Experimental crack growth testing has been performed at 550 °C on a range of fracture specimens using sections taken from a non-stress-relieved 316 steel weldment. These specimens include the compact tension, C(T), middle tension, M(T) and circumferentially cracked bar, CCB, geometries. Results are presented from two long-term creep crack growth (CCG) tests performed on M(T) weldment specimens and these are compared with available data on C(T) and CCB weldment specimens together with both long and short term tests on parent material for a range of specimen geometries. The creep crack initiation (CCI) and growth (CCG) behaviour from these tests has been analysed in terms of the C* parameter. As high levels of residual stress exist in non-stress-relieved weldments, the residual stresses remaining in the weldment specimens have therefore been quantified using the neutron diffraction technique. Long-term (low-load) tests are required on PM specimen to observe specimen constraint effects in 316 steel at 550 °C. When interpreted in terms of the C* parameter the CCG behavior of PM and Weldment materials follow the same trendline on low constraint geometries. However, significant difference is observed in the CCG behavior of PM and weldments on the high constraint C(T) geometry. Long term tests on C(T) specimen weldments are required to confirm the results found.

Sign in / Sign up

Export Citation Format

Share Document