The influence of test duration and geometry on the creep crack initiation and growth behaviour of 316H steel

Davies, Catrin M.; Dean, David; Yatomi, Masataka; Nikbin, Kamran

doi:10.1016/j.msea.2008.04.109

Cited by 46 publications

(24 citation statements)

References 7 publications

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“…As discussed in Ref. 32, the slopes of the experimental data fits shown in Fig. 9 are consistent with that predicted from the NSW models.…”

Section: Comparison Of Fe Predictions With the Experimental Datasupporting

confidence: 87%

“…24 In NSW model calculations, the characteristic distance r c is generally taken as the grain size of the material, thus can be taken as 0?05 mm for 316H stainless steel. 32 The C* parameter may be determined from the load line displacement rate response, : D, using the relation 33…”

Section: Nsw Creep Crack Growth Prediction Modelmentioning

confidence: 99%

“…4,32 All analyses have been performed on the high constraint C(T) specimen geometry, although wide- Fig. 7a and b for the FE data obtained under PS and PE conditions, respectively.…”

Section: Normalised Reference Stress Variation In Ccg Simulationsmentioning

confidence: 99%

See 2 more Smart Citations

Creep crack growth rate predictions in 316H steel using stress dependent creep ductility

Mehmanparast

Davies

Webster

et al. 2014

Materials at High Temperatures

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Short and long term trends in creep crack growth (CCG) rate data over test times of 500-30 000 h are available for Austenitic Type 316H stainless steel at 550uC using compact tension, C(T), specimens. The relationship between CCG rate and its dependence on creep ductility, strain rate and plastic strain levels has been examined. Uniaxial creep data from a number of batches of 316H stainless steel, over the temperature range 550-750uC, have been collected and analysed. Power-law correlations have been determined between the creep ductility, creep rupture times and average creep strain rate data with stress s normalised by flow stress s 0?2 over the range 0?2,s/s 0?2 ,3 for uniaxial creep tests times between 100 and 100 000 h. Creep ductility exhibits upper shelf and lower shelf values which are joined by a stress dependent transition region. The creep strain rate and creep rupture exponents have been correlated with stress using a two-stage power-law fit over the stress range 0?2,s/s 0?2 ,3 for temperatures between 550 and 750uC, where it is known that power-law creep dominates. For temperature and stress ranges where no data are currently available, the data trend lines have been extrapolated to provide predictions over the full stress range. A stress dependent creep ductility and strain rate model has been implemented in a ductility exhaustion constraint based damage model using finite element (FE) analysis to predict CCG rates in 316H stainless steel at 550uC. The predicted CCG results are compared to analytical constant creep ductility CCG models (termed NSW models), assuming both plane stress and plane strain conditions, and validated against long and short term CCG test data at 550uC. Good agreement has been found between the FE predicted CCG trends and the available experimental data over a wide stress range although it has been shown that upperbound NSW plane strain predictions for long term tests are overly conservative.

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“…As discussed in Ref. 32, the slopes of the experimental data fits shown in Fig. 9 are consistent with that predicted from the NSW models.…”

Section: Comparison Of Fe Predictions With the Experimental Datasupporting

confidence: 87%

Section: Nsw Creep Crack Growth Prediction Modelmentioning

confidence: 99%

See 1 more Smart Citation

Creep crack growth rate predictions in 316H steel using stress dependent creep ductility

Mehmanparast

Davies

Webster

et al. 2014

Materials at High Temperatures

View full text Add to dashboard Cite

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“…Separate fits have been made to the long‐ and short‐term tests of 316H in Fig. 5a due to the distinct CCG behaviour observed in the long‐term tests, where plasticity is limited and thus high specimen constraint effects maintained 30 . The CCG rate constants for these fits (see ) are given in Table 2.…”

Section: Creep Fracture Behaviourmentioning

confidence: 99%

Predicting creep crack initiation in austenitic and ferritic steels using the creep toughness parameter and time‐dependent failure assessment diagram

Davies

2009

Fatigue Fract Eng Mat Struct

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Methods for evaluating the creep toughness parameter, mat c K , are reviewed and mat c K data are determined for a ferritic P22 steel from CCG tests on compact tension, C(T), specimens of homogenous parent material (PM) and heterogeneous specimen weldments at 565 ° C and compared to similar tests on austenitic 316H stainless steel at 550 °C. Appropriate relations describing the time dependency of mat c K are determined accounting for data scatter. Considerable differences are observed in the form of the mat c K data and the time dependent failure assessment diagrams (TDFADs) for both the 316H and P22 steel. The TDFAD for P22 shows a strong time dependency but is insensitive to time for 316H. Creep crack initiation (CCI) times predictions are obtained using the TDFAD approach and compared to experimental results from C(T) specimens and feature components. The TDFAD based on PM properties can be used to obtain conservative prediction of the CCI on the weldments. Conservative predictions are almost always obtained when lower bound

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“…Hence, many investigations about the fracture behavior have been done at elevated temperature. [4][5][6][7][8][9][10][11][12] For example, Chao et al 12 have proposed the higher-order asymptotic crack-tip fields for a mode-I crack in a power-law creeping material under the plane strain conditions.…”

Section: Introductionmentioning

confidence: 99%

Creep crack initiation prediction considering constraint effect for pressurized pipelines with circumferential surface cracks

Dan

Jing

Zhao

et al. 2018

Fatigue Fract Eng Mat Struct

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Theoretical 2‐parameter C*‐Q* approaches and numerical simulation were conducted to investigate the creep crack initiation (CCI) time and the effect of constraints induced by the geometrical sizes of pipelines with circumferential surface cracks. The theoretical enhancement model of the C*‐Q* approaches under the transient creep condition, which considered the load‐independent constraint parameter Q*, was proposed to predict the CCI time around the crack front. The results revealed that the distribution regulation of Q* along the crack front for circumferential internal surface cracks and external surface cracks was similar. The maximum constraint level occurred near the deepest crack front part for cracks with small a/c (a/c < 0.4), while it occurred near the free surface for cracks with large a/c (a/c > 0.4). The constraint values at the same position (2Φ/π) increased with the increasing of the crack depth when a/c kept constant. In addition, the circumferential internal surface cracks of pipelines were proved more dangerous than the external surface cracks with the same geometrical size. Furthermore, the CCI times were decided by the peak values of constraint, or the CCI firstly occurred at the position where the constraint level was maximum. Additionally, the variation of hydrostatic stresses, triaxiality, and multiaxial strain factor considering the constraint parameter Q* was discussed. The suitability of the analytical C*‐Q* approaches was verified to predict CCI. The comparison of CCI times between the analytical approach and the BS 7910 as well as the finite element results demonstrated that the solutions under stress intensity factor–Riedel‐Rice control (initially by stress intensity factor and then by transient creep stress or Riedel‐Rice conditions)—were more accurate when internal pressure P < 18 MPa, but the solutions under Hutchinson‐Rice‐Rosengren–Riedel‐Rice control (initially by plastic Hutchinson‐Rice‐Rosengren control and then by Riedel‐Rice conditions) were more appropriate when P > 18 MPa. Finally, the accuracy of C*‐Q* 2‐parameter approaches and the suitability of finite element simulation were validated.

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The influence of test duration and geometry on the creep crack initiation and growth behaviour of 316H steel

Cited by 46 publications

References 7 publications

Creep crack growth rate predictions in 316H steel using stress dependent creep ductility

Creep crack growth rate predictions in 316H steel using stress dependent creep ductility

Predicting creep crack initiation in austenitic and ferritic steels using the creep toughness parameter and time‐dependent failure assessment diagram

Creep crack initiation prediction considering constraint effect for pressurized pipelines with circumferential surface cracks

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