Creep Crack Growth in an Austenitic Cr-Ni-Mn Steel

1990 ◽  
Vol 112 (3) ◽  
pp. 353-357 ◽  
Author(s):  
M. Tanaka ◽  
H. Iizuka ◽  
F. Ashihara
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Crack Growth ◽  
Creep Crack Growth ◽  
Crack Size ◽  
Grain Boundary Sliding ◽  
Creep Crack ◽  
Boundary Sliding

Effects of grain-boundary sliding and strenthening by serrated grain boundaries on creep-crack growth are investigated using an austenitic 21Cr-4Ni-9Mn steel at 973 K in air. In surface notched specimens, crack growth rate is lower in specimens with serrated grain boundaries than in those with normal straight grain boundaries at the same stress intensity factor (K1), but the difference in crack growth rate between these specimens decreases with crack growth. In smooth bar specimens, growth rate of the largest surface crack is correlated with the average amount of grain-boundary sliding, although a unique relationship is not found between them. Grain-boundary sliding controls the crack growth when the crack size is small, but total creep deformation becomes important and crack linkage occurs with increasing crack length, thus reducing the strengthening effects of serrated grain boundaries.

Fractal scaling and crack-size effects on creep crack growth

2020 ◽  
Vol 13 (3) ◽  
pp. 131-142
Author(s):  
Alberto Carpinteri ◽  
Gianni Niccolini ◽  
Alessio Rubino
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Creep Crack Growth ◽  
Compact Tension ◽  
Crack Size ◽  
Scaling Effects ◽  
Crack Growth Behaviour ◽  
Creep Crack ◽  
Creep Crack Growth Rate

Scaling effects on the creep crack growth behaviour are investigated by analyzing the results of compact tension (CT) tests on different-sized notched steel specimens appearing in the literature. Creep crack growth rate data are correlated to the elastic stress-intensity factor in terms of a Paris-type law, da∕dt = C0Kq, where C0 turns out to be a crack-size dependent coefficient of proportionality. Considering specimens with the same loading configuration (CT) and the same thickness, the observed crack-size effect on the creep crack growth rate is discussed on the basis of self-similarity considerations, and geometrically interpreted in terms of fractal tortuosity of the crack profile. A size-independent formulation of the creep crack growth law correlating renormalized quantities is finally deduced and confirmed by the experimental results.

The Variation of Crack Energy Density (CED) on Creep Crack Growth

2007 ◽  
Vol 353-358 ◽  
pp. 106-109
Author(s):  
C.S. Jeong ◽  
Byeung Gun Nam ◽  
Katsuhiko Watanabe
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Energy Density ◽  
Crack Growth ◽  
Early Stage ◽  
Creep Crack Growth ◽  
Creep Crack ◽  
Crack Behavior ◽  
Creep Crack Growth Rate ◽  
Unified Description

Creep crack growth (CCG) rate has been organized frequently by C* or Ct parameter However, crack behavior of early stage under unsteady state condition has not been explained. Crack energy density (CED), which has been proposed as a parameter that can provide a unified description of crack behavior with no restriction on constitutive equation, can give the general expression about creep crack growth rate. By applying Ct and the concept of CED to the results, we showed that creep crack growth rate for all ranges of creep can be explained in a unified way by CED and its derivatives. Moreover, the physical meaning of the Ct is clarified in the discussion.

Application of Creep Ductility Model for Evaluation Creep Crack Growth Rate of Type 316SS Series

2005 ◽  
Vol 475-479 ◽  
pp. 1433-1436 ◽  
Author(s):  
Woo Gon Kim ◽  
Hyun Hie Kim ◽  
Kee Bong Yoon ◽  
Woo Seog Ryu
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Creep Crack Growth ◽  
Creep Ductility ◽  
Creep Crack ◽  
Creep Crack Growth Rate ◽  
Applied Stresses

This paper is to evaluate the creep crack growth rate (CCGR) of the type 316SS series: 316SS, 316FR and 316LN, and to apply a creep ductility model. A number of the data are collected through wide literature surveys and experiment, and evaluated by the C* parameter. The results of the CCGR data were nearly matched with a small scattering band regardless of the different applied stresses, temperatures and test specimens configuration. In the CCGR, type 316FR and 316LN steels were slower than type 316SS. Type 316SS showed a better agreement in the application of the creep ductility model than the type 316FR and 316LN steels.

Statistical Analysis of Creep Crack Growth Behavior in Modified 9Cr-1Mo Steel

2010 ◽  
Vol 654-656 ◽  
pp. 516-519
Author(s):  
Seon Jin Kim ◽  
Woo Gon Kim ◽  
Ik Hee Jung ◽  
Yong Wan Kim
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Probability Distribution ◽  
Weibull Distribution ◽  
Crack Growth ◽  
Creep Crack Growth ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Creep Crack ◽  
Creep Crack Growth Rate

In this paper, a series of statistical studies were conducted on creep crack growth behavior of Grade 9Cr-1Mo steel for next generation reactor. Creep crack growth tests were performed on pre-cracked compact tension (CT) specimens under the applied load ranges from 3800 to 5000N at the identical temperature condition of 600oC. The creep crack growth behavior has been analyzed statistically using the empirical equation between crack growth rate da/dt and C* parameter, namely da/dt=B(C*)q. First, the determination methods of B and q obtained from experiments were investigated by the least square fitting method and the mean value method. The probability distribution functions of B and q have been investigated using the normal, log-normal and Weibull distribution. The constant B and q are followed well 2-parameter Weibull. Second, the creep crack growth rate data were generated by Monte-Carlo simulation method assuming the 2-parameter Weibull in B and q parameters. The probability distribution of creep crack growth rate for arbitrary C* parameter values seems to follow well Weibull distribution.

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