The Effect of Specimen Size for the P91 Steel at Elevated and High Temperatures

2017 ◽  
Author(s):  
Ludek Stratil ◽  
Filip Siska ◽  
Hynek Hadraba ◽  
Stanislava Fintova ◽  
Tomas Mrna ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Size Effect ◽  
Temperature Dependence ◽  
Pressure Vessels ◽  
Specimen Size ◽  
Dynamic Strain ◽  
Dynamic Strain Ageing ◽  
P91 Steel ◽  
Piping Systems ◽  
Curve Determination

The contribution aims to evaluate fracture toughness of the P91 steel in the ductile regime. This steel is broadly used for applications for pressure vessels and piping systems. The J–R curves were obtained using 1T, 0.5T and 0.25T CT specimens at 23 °C and using 0.5T and 0.25T CT specimens up to 600 °C. The energy normalization method for the J–R curve determination according to the ASTM E1820 was used. The resistance to crack propagation shows temperature dependence and the dynamic strain ageing effect with minimum values at 400 °C. Both specimen sizes 0.5T and 0.25T give a similar trend of the temperature dependence of fracture toughness. However, the size effect is observed as fracture toughness decreases with the specimen size. The results obtained are compared with the results of other authors pointing the specimen size effect and the temperature dependence of the steel.

Fracture toughness in the dynamic strain ageing regime

1991 ◽  
Vol 25 (11) ◽  
pp. 2585-2588 ◽  
Author(s):  
M. Srinivas ◽  
G. Malakondaiah ◽  
K.Linga Murty ◽  
P.Rama Rao
Keyword(s):  
Fracture Toughness ◽  
Dynamic Strain ◽  
Dynamic Strain Ageing ◽  
Strain Ageing

SPECIMEN SIZE EFFECT ON J-INTEGRAL FRACTURE TOUGHNESS

1978 ◽  
pp. 267-272 ◽  
Author(s):  
D. Sunamoto ◽  
M. Satoh ◽  
T. Funada ◽  
M. Tomimatsu
Keyword(s):  
Fracture Toughness ◽  
Size Effect ◽  
Specimen Size ◽  
J Integral

Influence of Dynamic Strain Ageing and Long Term Ageing on Deformation and Fracture Behaviors of Alloy 617

2016 ◽  
Vol 879 ◽  
pp. 306-311
Author(s):  
Guo Cai Chai ◽  
Mattias Calmunger ◽  
Sten Johansson ◽  
Johan Moverare ◽  
Joakim Odqvist
Keyword(s):  
Fracture Toughness ◽  
Dynamic Strain ◽  
Dislocation Slip ◽  
Aged Alloy ◽  
Dynamic Strain Ageing ◽  
Alloy 617 ◽  
Strain Ageing ◽  
Damage And Fracture ◽  
Fracture Behaviors

Influences of dynamic strain ageing and long term ageing on deformation, damage and fracture behaviors of Alloy 617 material have been studied. Dynamic strain ageing can occur in this alloy at temperature from 400 to 700°C, which leads to a strain hardening and also an increase in fracture strain due to plastic deformation caused by twinning. Long term ageing at 700°C for up to 20 000 hours can cause different precipitation such as γ ́, M6C (Mo-rich) and M23C6 (Cr-rich) carbides. These carbides are both inter-and intra-granular particles. The long term ageing reduces the fracture toughness of the material, but the alloy can still have rather high impact toughness and fracture toughness even with an ageing at 700°C for 20 000 hour. The mechanisms have been studied using electron backscatter detection and electron channeling contrast imaging. It shows that besides dislocation slip, twinning is another main deformation mechanism in these aged Alloy 617 materials. At the crack front, plenty of micro or nanotwins can be observed. The formation of these twins leads to a high ductility and toughness which is a new observation or a new concept for this type of material.

Ductile Crack Growth Resistance and Rotation Behavior of Miniature C(T) Specimen

2020 ◽  
Author(s):  
Tomoki Shinko ◽  
Masato Yamamoto
Keyword(s):  
Fracture Toughness ◽  
Size Effect ◽  
Crack Growth ◽  
Crack Extension ◽  
Crack Tip ◽  
Crack Growth Resistance ◽  
Specimen Size ◽  
Ductile Crack ◽  
Rotation Center ◽  
Ductile Crack Growth

Abstract A utilization of a miniature compact tension (Mini-C(T)) specimen is expected to enable effective use of limited remaining surveillance specimens for the structural integrity assessment of a Reactor Pressure Vessel (RPV). For developing a direct fracture toughness evaluation method using Mini-C(T) specimen in the upper-shelf temperature range as well as ductile-brittle transition temperature range, this study is aimed to experimentally characterize the Mini-C(T) specimen’s size effect on ductile crack growth resistance and interpolate its mechanism. Mini-C(T) specimen and 0.5T-C(T) specimen were prepared from a Japanese RPV steel SQV2A, and the ductile crack growth tests were conducted on them at room temperature. As a result, the crack growth resistance of Mini-C(T) and 0.5T-C(T) specimens are comparable if the crack extension Δa is less than 0.5 mm. On the other hand, if Δa exceeds 0.5 mm, the crack growth resistance of Mini-C(T) specimen becomes lower than that of 0.5T-C(T) specimen. The measurements of stretch zone width and depth support the fact that the fracture toughness for ductile crack initiation of Mini-C(T) specimen is lower than that of 0.5T-C(T) specimen. From the rotational (crack mouth opening) deformation of Mini-C(T) specimen was measured by simultaneously measuring load-line and front face displacements. The distance between the crack tip and the rotation center of Mini-C(T) specimen is smaller than that of 0.5T-C(T) specimen during the test. Furthermore, The plastic zone in front of the crack tip reaches the rotation center up to the crack extension of Δa = 0.3 mm on Mini-C(T) specimen, indicating that the mechanism of the specimen size effect of Mini-C(T) specimen is likely a plastic constraint due to the influence of the rotation center locating near the crack tip. This suggests that the specimen size effect of Mini-C(T) specimen on ductile crack growth resistance is expected to be corrected by considering an effect of the plastic constraint.

Dynamic strain ageing in C -Mn steels and associated welds. II. Effect on fracture toughness behaviour

2001 ◽  
Vol 98 (5) ◽  
pp. 473-484 ◽  
Author(s):  
D. Wagner ◽  
J. C. Moreno ◽  
C. Prioul ◽  
J. M. Frund ◽  
B. Houssin
Keyword(s):  
Fracture Toughness ◽  
Dynamic Strain ◽  
Dynamic Strain Ageing ◽  
Strain Ageing
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