Creep crack growth of GH3535 alloy at elevated temperatures

2011 ◽

Vol 230-232 ◽

pp. 596-599

Author(s):

Li Jie Chen ◽

Zun Qun Gong ◽

Qi Zhao

Keyword(s):

Stainless Steel ◽

Austenitic Stainless Steel ◽

Crack Propagation ◽

Crack Growth ◽

Elevated Temperatures ◽

Creep Crack Growth ◽

Tensile Creep ◽

Computational Error ◽

Propagation Length ◽

Creep Crack

First, tensile creep curve and creep propagation tests are conducted for austenitic stainless steel 0Cr18Ni9, i.e. 304 stainless steel at 550°C. The corresponding time hardening creep law is given for stresses ranging from 240 to 320 Mpa and the creep crack propagation length under a tension load of 10kN is measured by using QUESTAR long focus microscope system. Second, with the commercial finite element (FE) code ANSYS, the critical crack tip opening displacement (CTOD) is considered as crack propagation criterion to simulate the creep crack growth in the standard compact tension (CT) specimen. The FE predictions of the creep crack length in the primary and secondary stages are found to agree reasonably with the experimental results. The maximum computational error between the predictions and the experiment results is within 10%. Hence, the critical CTOD is a feasible criterion for crack growth simulations at elevated temperatures.

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Sagbo Effect on Creep Crack Growth of Inconel 718 Superalloy at Elevated Temperatures

Superalloys 718, 625, 706 and Various Derivatives (1994) ◽

10.7449/1994/superalloys_1994_579_579 ◽

1994 ◽

Cited By ~ 1

Author(s):

B.S.-J. Kang ◽

G. Zhang ◽

P. Liu ◽

M. Sutton ◽

J. Lyons

Keyword(s):

Crack Growth ◽

Inconel 718 ◽

Elevated Temperatures ◽

Creep Crack Growth ◽

Creep Crack ◽

Inconel 718 Superalloy

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Specimen Geometry and Size Effects on the Creep Crack Growth Behaviour of P91 Weldments

Volume 6A: Materials and Fabrication ◽

10.1115/pvp2013-97417 ◽

2013 ◽

Cited By ~ 2

Author(s):

A. Mehmanparast ◽

S. Maleki ◽

M. Yatomi ◽

K. M. Nikbin

Keyword(s):

Crack Growth ◽

Elevated Temperatures ◽

Creep Crack Growth ◽

Compact Tension ◽

Initial Crack ◽

Parent Material ◽

Specimen Geometry ◽

Crack Growth Behaviour ◽

Creep Crack ◽

Constraint Effects

The influence of specimen size and geometry on the creep crack growth (CCG) behaviour of P91 parent and weld materials at 600–625 °C has been examined. CCG tests have been performed on compact tension, C(T), specimens with an initial crack located in the heat affected zone (HAZ). Further tests have also been performed on specimens made of parent material (PM). Higher creep crack growth rates have been found in the HAZ material compared to the PM when the CCG rate is characterized using the C* fracture mechanics parameter. The experimental data from these tests are compared to those of available from specimens with different size and geometries. The results are discussed in terms of specimen geometry and constraint effects on the CCG behaviour of P91 weldments at elevated temperatures.

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Modelling Crack Growth in the Life Assessment of Elevated Temperature Components

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.348-349.709 ◽

2007 ◽

Vol 348-349 ◽

pp. 709-712

Author(s):

Kamran M. Nikbin

Keyword(s):

Fracture Mechanics ◽

Crack Growth ◽

Plane Strain ◽

Elevated Temperatures ◽

Creep Crack Growth ◽

Crack Propagation Rate ◽

Life Assessment ◽

Manganese Steel ◽

Growth Data ◽

Creep Crack

Modelling of Creep Crack Growth (CCG) using analytical and numerical methods is relevant to life assessment procedures of components operating at elevated temperatures. This paper compares an analytical crack prediction and a numerical based virtual CCG technique used in fracture mechanics components with sample experimental results. Two approaches are presented. First the well developed strain exhaustion model called the NSW and the modified NSW-MOD models which predict plane stress/strain bound crack initiation and growth rates for engineering alloys and the second a damage-based approach used to numerically predict the crack propagation rate in Finite Element models of fracture mechanics specimens. The results from both methods are correlated against an independently determined C* parameter. As an example the NSW and the extended NSW-MOD strain exhaustion models are applied to compare to the experimental data and FE predictions for two steels at Carbon-Manganese steel tested at 360 oC and a weld 316H stainless steel at 550 oC. For values of C* within the limits of the present creep crack growth data presented the plane strain crack growth rate predicted from the numerical analysis is found to be less conservative than the plane strain NSW model but more conservative than plane strain NSW-MOD model.

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Creep Crack Growth Predictions in 316H Steel Over a Wide Range of Stresses and Temperatures

Volume 6A: Materials and Fabrication ◽

10.1115/pvp2014-28709 ◽

2014 ◽

Cited By ~ 1

Author(s):

A. Mehmanparast ◽

C. M. Davies ◽

K. M. Nikbin ◽

G. A. Webster

Keyword(s):

Crack Growth ◽

Elevated Temperatures ◽

Prediction Models ◽

Creep Crack Growth ◽

Life Assessment ◽

Creep Ductility ◽

Crack Growth Behaviour ◽

Creep Crack ◽

Uniaxial Creep ◽

Wide Range

The prediction of the creep crack growth (CCG) behaviour in engineering materials is of great importance in the life assessment of power plant components. The conventional technique to predict CCG is to employ uniaxial creep properties and appropriate damage models in finite element (FE) simulations or analytical CCG prediction models. Uniaxial creep trends for Type 316H SS have been recently estimated for a wide range of stresses and temperatures in [1] and FE CCG predictions have been made at 550 °C and validated through comparison with the experimental data. In this paper, FE CCG predictions using the developed uniaxial creep trends for a wide range of stresses and temperatures are presented and the results are compared with the predicted CCG trend at 550 °C and also with the analytical constant creep ductility NSW CCG prediction models. The results from FE predictions are discussed in terms of the temperature effects on the creep deformation and crack growth behaviour of components operating at elevated temperatures.

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An Engineering Approach to the Prediction of Creep Crack Growth

Journal of Engineering Materials and Technology ◽

10.1115/1.3225859 ◽

1986 ◽

Vol 108 (2) ◽

pp. 186-191 ◽

Cited By ~ 138

Author(s):

K. M. Nikbin ◽

D. J. Smith ◽

G. A. Webster

Keyword(s):

Crack Growth ◽

Plane Strain ◽

Plane Stress ◽

Elevated Temperatures ◽

Process Zone ◽

Creep Crack Growth ◽

Crack Tip ◽

Creep Damage ◽

Creep Ductility ◽

Creep Crack

This paper is concerned with assessing the integrity of cracked engineering components which operate at elevated temperatures. Fracture mechanics parameters are discussed for describing creep crack growth. A model is presented for expressing growth rate in terms of creep damage accumulation in a process zone ahead of the crack tip. Correlations are made with a broad range of materials exhibiting a wide spread of creep ductilities. It is found that individual propagation rates can be predicted with reasonable accuracy from a knowledge only of the material uni-axial creep ductility. An engineering creep crack growth assessment diagram is proposed which is independent of material properties but which is sensitive to the state of stress at the crack tip. Approximate bounds are presented for plane stress and plane strain situations and it is shown that crack growth rates about fifty times faster are expected under plane strain conditions than when plane stress prevails.

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