Creep Crack Growth in X20CrMoV 12 1 Steel and Its Weld Joint

2000 ◽  
Vol 123 (2) ◽  
pp. 191-196 ◽  
Author(s):  
Y. K. Park ◽  
K. S. Kim ◽  
Y. K. Chung ◽  
J. J. Park
Keyword(s):  
Steady State ◽  
Crack Growth ◽  
Weld Joint ◽  
Computational Study ◽  
Creep Crack Growth ◽  
Steady State Creep ◽  
Creep Crack ◽  
Creep Analysis ◽  
Calculated Load ◽  
Crack Growth Rates

A combined experimental and computational study is carried out on creep crack growth in X20CrMoV 12 1 steel and its weld joint. Crack growth tests are conducted on compact specimens at 545°C. For weld specimens, the crack propagates in the heat-affected zone parallel to the fusion line. It is found that C*t correlates crack growth rates satisfactorily under the loads used in the test not only for base metal specimens but also for weld specimens. An elastic-plastic-steady-state creep analysis of crack growth is performed using a finite element code. Calculated load point displacement rates agree with experimental measurements during steady-state crack growth. The creep zone is asymmetric, and it becomes more so in weld specimens as the crack propagates. Yet the mode II effect appears to be insignificant.

Assessment of Creep Crack Growth Rates for Grade 91 Weld Joint at 550°C

2018 ◽  
Author(s):  
Woo-Gon Kim ◽  
Jae-Young Park ◽  
Hyeong-Yeon Lee ◽  
Eung-Seon Kim ◽  
Seon-Jin Kim
Keyword(s):  
Crack Growth ◽  
Weld Joint ◽  
Growth Rates ◽  
Creep Crack Growth ◽  
Tensile Creep ◽  
Fracture Parameter ◽  
Creep Crack ◽  
Elevated Temperature Design ◽  
Grade 91 ◽  
Crack Growth Rates

This study presents assessment of creep crack growth rates (CCGRs) for the base metal (BM), weld metal (WM), and heat affected zone (HAZ) of Gr. 91 weld joint, which was prepared by a shield metal arc weld (SMAW) method. A series of tensile, creep, creep crack growth (CCG) tests were performed for the BM, WM, and HAZ at the identical temperature of 550°C. The CCGR laws for the BM, WM and HAZ were constructed and compared in terms of a C*-fracture parameter. In addition, the CCGR law tested for BM was compared to that of RCC-MRx code. For a given value of C*, the WM and HAZ were almost similar in the CCGR, but they were significantly faster than the BM. This reason was closely attributed to the higher creep rate in the WM and HAZ than the BM. Currently elevated temperature design (ETD) code in French, RCC-MRx was found to be non-conservative in the CCGR when compared with the present investigation.

OS0708 The Effect of Multi-axial Stress on Creep Crack Growth for Weld Joint of P92

2008 ◽  
Vol 2008 (0) ◽  
pp. _OS0708-1_-_OS0708-2_
Author(s):  
Ryuji Sugiura ◽  
Kazuto Suzuki ◽  
A. Toshimitsu Yokobori Jr. ◽  
Masaaki Tabuchi
Keyword(s):  
Crack Growth ◽  
Weld Joint ◽  
Axial Stress ◽  
Creep Crack Growth ◽  
Creep Crack

Experimental Investigation of Constraint Effects on Creep Crack Growth

2002 ◽  
Author(s):  
Adam D. Bettinson ◽  
Noel P. O’Dowd ◽  
Kamran M. Nikbin ◽  
George A. Webster
Keyword(s):  
Stainless Steel ◽  
Crack Growth ◽  
Creep Crack Growth ◽  
Compact Tension ◽  
Growth Data ◽  
Creep Crack ◽  
Low Constraint ◽  
Constraint Effects ◽  
Crack Growth Model ◽  
Crack Growth Rates

In this work the effects of specimen size and type on creep crack growth rates in stainless steel are examined. Experiments have been carried out on high constraint compact tension specimens (CT) and low constraint centre cracked panels (CCP) of ex-service 316H stainless steel. All testing was carried out at 550°C. Constraint effects have been observed in the data, with the large CT specimens having the fastest crack growth rate and the small CCP specimens the slowest. These trends are consistent with those that would be predicted from two parameter (C*–Q) theories. However, it is found that a constraint dependent creep crack growth model based on ductility exhaustion overpredicts the constraint dependence of the crack growth data.

The Influence of Metallurgical and Mechanical Pre-Damage on Creep-Crack and Fatigue-Crack Growth Rates of CrMoV Steel

2004 ◽  
Author(s):  
Masaru Sekihara ◽  
Shigeo Sakurai
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Creep Crack Growth ◽  
Creep Crack ◽  
The Relationship ◽  
Crack Growth Rates

The effects of mechanical degradation on the creep- and fatigue-crack growth rates in power plants operated long-term were studied. Creep-crack growth tests and fatigue-crack growth tests were performed using creep-pre-strained and repetitive-strained CrMoV rotor-steel specimens. It was found that the creep-crack growth rates, da/dt, of the creep-pre-damaged specimens were larger than those of virgin specimens under constant load. It was also found that under the same stress intensity factor K, da/dt in the case of about 10%-crept and creep void induced specimens was increased five times, while in the case of 0.8%- and 2.8%-crept specimens, it only increased a little. However, all the data fell in a narrow scatter band in the relationship between C* and da/dt. The effect of long-term operating degradation appeared on the creep- and fatigue-damage under the Slow-Fast waveform. Also the crack density was larger in the damaged specimens compared with the virgin specimens. Other results showed that the fatigue-crack growth rates, da/dN, of creep- and fatigue-pre-damaged specimens were larger than those of virgin specimens. Under the same stress intensity factor range ΔK, da/dN in a specimen with approximately 10%-creep was increased 20 times. Moreover da/dN in fatigue-pre-damaged specimens was accelerated 10 times. However, the results of the strain-controlled crack growth test fell in a narrow scatter band in the relationship between J integral range ΔJ and da/dN. These results suggest that the creep remaining lives and fatigue remaining lives of mechanically damaged CrMoV steel can be estimated using the C* & ΔJ values considering the creep rate and the deformation rate of the pre-damaged materials and the da/dt and da/dN values of the virgin material.

Prediction of creep crack growth from uniaxial creep data

1984 ◽  
Vol 396 (1810) ◽  
pp. 183-197 ◽  
Keyword(s):  
Crack Growth ◽  
Growth Rates ◽  
Process Zone ◽  
Creep Crack Growth ◽  
Creep Process ◽  
Uniaxial Tensile ◽  
Creep Data ◽  
Creep Ductility ◽  
Creep Crack ◽  
Crack Growth Rates

In this paper uniaxial tensile creep data are used in conjunction with fracture mechanics concepts to predict creep crack growth rates in materials having a wide range of creep ductilities. A model is proposed of creep damage accumulation in a process zone ahead of the crack tip. The model allows all stages of creep to be incorporated in an approximate manner and creep ductility to be stress and stress-state sensitive. Good agreement is obtained with experimental crack growth data on a range of low alloy steels, a stainless steel, an aluminium alloy and a nickel-base superalloy. It is found that cracking rate is insensitive to the creep process zone size but inversely proportional to creep ductility. Crack growth rates under plane strain conditions are shown to be about fifty times those for plane stress loading.

Finite Element Damage Simulations for Creep Crack Growth of SS316H With Different Geometries

2011 ◽  
Author(s):  
Chang-Sik Oh ◽  
Nak-Hyun Kim ◽  
Han-Sang Lee ◽  
Yun-Jae Kim
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Crack Growth ◽  
Creep Test ◽  
Damage Model ◽  
Creep Crack Growth ◽  
Test Results ◽  
Creep Ductility ◽  
Creep Crack ◽  
Crack Growth Rates

In this paper, creep crack growth simulations were performed based on finite element (FE) damage simulations for several types of test specimens such as C(T), CS(T), SEN(T), M(T) and SEN(B). The Graham-Walles creep law was adopted to describe all three phases of creep. The Creep parameters were obtained from uni-axial creep test results of SS316H at 550°C. Damage model was also included based on creep ductility exhaustion concept, which is defined as the ratio of creep strain to the multi-axial creep ductility. Creep crack growth rates resulting from FE simulations were compared with the experimental data.

Three Dimensional Criterion for Creep Crack Propagation in C(T) Specimen

2016 ◽  
Vol 853 ◽  
pp. 142-147
Author(s):  
Wen Ming Ye ◽  
Xu Teng Hu ◽  
Wan Lin Guo ◽  
Ying Dong Song
Keyword(s):  
Crack Propagation ◽  
Crack Growth ◽  
Growth Rates ◽  
Three Dimensional ◽  
Creep Crack Growth ◽  
Growth Control ◽  
Compact Tension ◽  
Thickness Effect ◽  
Creep Crack ◽  
Crack Growth Rates

Experimental of two kinds of compact tension (CT) specimens’ creep crack propagation are carried out in this paper. Traditional fracture mechanics and three-dimensional fracture theory are compared and the results show that: The K-Tz two-parameter model can eliminate the thickness-effect on the crack growth rates in the relatively low K range, however when K exceed certain values the effect of thickness for crack growth rates still exists; The Ct and Ct-Tz model can describe the thickness-effect of creep crack growth rates in regions of high Ct; When the crack tip stress intensity factor K of the two kinds of thickness (B=5 mm, B=10 mm) specimens equal to 35 and 31 respectively, this material’s creep crack growth control parameter change from K to Ct.

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