Assessment and Test of the Creep-Fatigue Crack Behaviour for a High Temperature Component

2008 ◽  
Author(s):  
Hyeong-Yeon Lee ◽  
Jae-Han Lee ◽  
Kamran Nikbin
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Crack Initiation ◽  
316L Stainless Steel ◽  
Fatigue Crack Initiation ◽  
Present Specimen ◽  
High Temperature Component ◽  
Creep Fatigue ◽  
Temperature Component ◽  
Creep Fatigue Crack

Creep-fatigue crack behaviour has been investigated for a welded component with 316L stainless steel and Mod. 9Cr-1Mo steel through an assessment and test. The evaluation of creep-fatigue crack initiation and propagation was carried out for 316L stainless steel according to the French RCC-MR A16 guide, and evaluation on creep-fatigue crack initiation for Mod.9Cr-1Mo steel in a specimen was carried out with an extended A16 method. A test for a structural specimen with a diameter of 500mm, height of 440mm and thickness of 6.3mm was performed to compare its results with that by assessment according to the A16 guide. The specimen was subjected to creep-fatigue loads with two hours of a dwell time at 600°C and variable primary loads. The creep-fatigue crack behaviours for the two materials were assessed, observed and compared. The results showed that the A16 guide for the austenitic stainless steel was overly conservative for the assessment of creep-fatigue crack initiation while it was reasonably conservative for creep-fatigue crack growth for the present specimen.

Assessment and Test of the Creep-Fatigue Crack Behavior for a High Temperature Component

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Hyeong-Yeon Lee ◽  
Jae-Han Lee ◽  
Kamran Nikbin
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Crack Initiation ◽  
316L Stainless Steel ◽  
Fatigue Crack Initiation ◽  
Steel Specimen ◽  
Present Specimen ◽  
Crack Behavior ◽  
Creep Fatigue ◽  
Creep Fatigue Crack

Creep-fatigue crack behavior has been investigated for a welded component with 316L stainless steel and Mod. 9Cr–1Mo steel through assessment and test. The evaluation of creep-fatigue crack initiation and propagation was carried out for 316L stainless steel according to the French RCC-MR A16 guide, and the evaluation of creep-fatigue crack initiation for a Mod.9Cr–1Mo steel specimen was carried out with an extended A16 method. A test for a structural specimen with a diameter of 500 mm, height of 440 mm, and thickness of 6.3 mm was performed to compare its results with that by an assessment according to the A16 guide. The specimen was subjected to creep-fatigue loads with 2 h of dwell time at 600°C and various primary loads. The creep-fatigue crack behaviors for the two materials were assessed, observed, and compared. The results showed that the A16 guide for the austenitic stainless steel was fairly conservative for the assessment of creep-fatigue crack initiation while it was reasonably conservative for creep-fatigue crack growth for the present specimen.

Creep-Fatigue Damage and Crack Initiation for a Mod 9Cr-1Mo Structure With Weldments

2007 ◽  
Author(s):  
Hyeong-Yeon Lee ◽  
Se-Hwan Lee ◽  
Jong-Bum Kim ◽  
Jae-Han Lee
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Fatigue Damage ◽  
Hold Time ◽  
Fatigue Crack Initiation ◽  
Creep Damage ◽  
Steel Specimen ◽  
Structural Test ◽  
Creep Fatigue ◽  
Creep Fatigue Crack

A structural test and evaluation on creep-fatigue damage, and creep-fatigue crack initiation have been carried out for a Mod. 9Cr-1Mo steel structural specimen with weldments. The conservatisms of the design codes of ASME Section III subsection and NH and RCC-MR codes were quantified at the welded joints of Mod.9Cr-1Mo steel and 316L stainless steel with the observed images from the structural test. In creep damage evaluation using the RCC-MR code, isochronous curve has been used rather than directly using the creep law as the RCC-MR specifies. A y-shaped steel specimen of a diameter 500mm, height 440mm and thickness 6.35mm is subjected to creep-fatigue loads with two hours of a hold time at 600°C and a primary nominal stress of 30MPa. The defect assessment procedures of RCC-MR A16 guide do not provide a procedure for Mod.9Cr-1Mo steel yet. In this study application of σd method for the assessment of creep-fatigue crack initiation has been examined for a Mod. 9Cr-1Mo steel structure.

Environmental Effects on Fatigue Crack Initiation in 2.25 Cr-1 Mo Steel and 316L Stainless Steel

1988 ◽  
Vol 110 (3) ◽  
pp. 240-246
Author(s):  
V. K. Mathews ◽  
T. S. Gross
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Crack Initiation ◽  
Room Temperature ◽  
316L Stainless Steel ◽  
Silicone Oil ◽  
Fatigue Crack Initiation ◽  
Type A ◽  
Order Of Magnitude ◽  
Number Of Cycles

Blunt notch fatigue crack initiation tests for Type A387 2.25 Cr-1 Mo steel and 316L stainless steel were performed in air at room temperature, in silicone oil at room temperature, in V-131B coal process solvent at 100°C, and in chlorine-modified V-131B coal process solvent at 100°C. For both steels the most damaging environment was room temperature air. The number of cycles to initiate a crack were almost identical in the coal process solvent and the silicone oil for the Type A-387 steel. These two environments resulted in the longest crack initiation lifetime for the Type A-387 steel. The crack initiation lifetime for the Type A-387 steel in the chlorine modified V-131 B coal process solvent was roughly a factor of five less than the lifetime in the silicone oil and the unmodified coal process solvent. The crack initiation lifetime for the Type A-387 steel in room temperature air was a factor of 30 less than the lifetime in the silicone oil or the unmodified coal process solvent. The improvement of the crack initiation lifetime for the Type A-387 steel in the unmodified coal process solvent and the silicone oil is attributed to protection of the material from embrittlement from room temperature air. The decrease in crack initiation lifetime in the chlorine modified coal process solvent indicates that chlorine can be an active embrittling agent in the coal process solvent. The crack initiation lifetime for 316L stainless steel was longest in the silicone oil. The lifetime decreased somewhat in the unmodified coal process solvent with a further decrease for the chlorine modified coal solvent. The crack initiation lifetime in air was an order of magnitude lower than the lifetime in the silicone oil. The silicone oil and the coal process solvent apparently protected the 316L stainless from the embrittlement in air. However, the coal process solvent is not entirely inert as in the case of Type A-387 steel. The chlorine is an active embrittling agent for the 316L stainless steel in the coal process solvent.

Creep-Fatigue Crack Initiation Assessments of an Instrument Guide Tube Within a Superheater Header

2014 ◽  
Author(s):  
Jinhua Shi ◽  
Hassam Dodia
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Fatigue Damage ◽  
Material Properties ◽  
Fatigue Crack Initiation ◽  
Guide Tube ◽  
New Approach ◽  
Weld Material ◽  
Creep Fatigue ◽  
Creep Fatigue Crack

In order to extend the boiler lives at Advanced Gas-Cooled Reactor (AGR) nuclear power stations in the UK, new temperature measuring instrumentation to monitor reactor gas temperature has been proposed to install on the bore of an intact boiler tube to provide additional boiler operating data to support the station lifetime extension. This paper details a creep-fatigue crack initiation assessment of the proposed installation of an instrument guide tube within the superheater header using the latest R5 high temperature assessment procedures based on detailed finite element thermal transient stress analysis values for a bounding start-up and shutdown cycle. The fatigue damage at welds has been calculated based on both weld and parent material properties. The new approach for assessing weldments has been used in this paper. This new approach involves splitting the existing Fatigue Strength Reduction Factor (FSRF) into a Weldment Endurance Reduction (WER), which accounts for reduced fatigue endurance due to weld imperfections, and a Weldment Strain Enhacement Factor (WSEF), which accounts for material mismatch and local geometry. The creep assessments of the weld material locations have been carried out on both parent and weld material properties including the welding residual stress. The total creep-fatigue damage is then obtained as the sum of fatigue damage, Df, and creep damage, Dc.

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