Effect of Residual Stresses Caused by Thermal Treatment on Creep Crack Growth Rate in Aluminium Gas Cylinders

1998 ◽  
Author(s):  
Raafat Ibrahim ◽  
Dmitry Ischenko
Keyword(s):  
Residual Stress ◽  
Growth Rate ◽  
Residual Stresses ◽  
Crack Growth ◽  
Creep Crack Growth ◽  
Stress Distributions ◽  
Creep Crack ◽  
Quenching Process ◽  
Creep Crack Growth Rate ◽  
Gas Cylinders

Abstract Aluminum gas cylinders, which are in common use for various purposes, are susceptible to creep crack growth. Residual stresses introduced during the quenching process in aluminum gas cylinders contribute to the development of cracks. This may result in leakage or fracture of the cylinders. Finite element studies were conducted to evaluate the effect of the quenching process on through thickness inelastic strain and the residual stress distributions in the neck area of gas cylinders. Numerical modeling and experimental studies confirmed that a high level of tensile residual stresses exists on the inner surface of aluminum gas cylinders’ neck which is susceptible to cracking. The relationship between the amount of residual stresses and cooling conditions was established. The obtained residual stress distributions were included in the calculation of the creep crack growth rates. It was shown that residual stresses caused by manufacturing processes have a significant effect on the creep crack growth rate.

Measurements of Residual Stresses in 316 Stainless Steel Weldments

2010 ◽  
Author(s):  
C. M. Davies ◽  
D. Hughes ◽  
R. C. Wimpory ◽  
David W. Dean ◽  
K. M. Nikbin
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Crack Growth ◽  
Creep Crack Growth ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Stress Distributions ◽  
Tension Specimen ◽  
Creep Crack ◽  
Term Creep

Neutron diffraction measurements have been performed to quantify the residual stresses distributions in austenitic type 316 stainless steel Manual Metal Arc (MMA) weldment sections, which are similar to those used in creep crack growth testing. Measurements have been taken along the expected crack path in these samples to determine the influence of residual stresses on high temperature crack growth. The influence of EB welding extension pieces onto the weldments sections, in order to increase specimen size, and sample cutting for compact tension specimen manufacture are also examined. Similar stress distributions have been measured in nominally identical MMA weldments sections, where peak stresses of up to 120 MPa have been shown. The effects of the EB weld used to attach extension pieces to the weldments sections dominate over the MMA weldments residual stress distributions in these samples, and increases the peak stresses by up to a factor of three. Significant stress relaxation takes place during compact tension specimen manufacture, and in addition creep strain accumulation will further relax these residual stresses. Residual stress effects are therefore considered to only influence the creep crack initiation period in short-term creep crack growth tests. However, in long-term creep crack growth tests, the residual stresses may also influence subsequent creep crack growth behaviour.

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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