scholarly journals High temperature embrittled duplex stainless steels: influence of the chemical composition on the fatigue crack propagation

2017 ◽  
Vol 3 ◽  
pp. 308-315
Author(s):  
Francesco Iacoviello ◽  
Vittorio Di Cocco ◽  
Ester Franzese ◽  
Stefano Natali
Keyword(s):  
Fatigue Crack ◽  
High Temperature ◽  
Chemical Composition ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Stainless Steels ◽  
Duplex Stainless Steels

Stable and Unstable Fatigue Crack Propagation During High Temperature Creep-Fatigue in Austenitic Steels: The Role of Precipitation

1979 ◽  
Vol 101 (3) ◽  
pp. 275-283 ◽  
Author(s):  
G. J. Lloyd ◽  
J. Wareing
Keyword(s):  
Fatigue Crack ◽  
High Temperature ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Austenitic Steels ◽  
High Temperature Creep ◽  
Temperature Creep ◽  
Creep Fatigue

The distinction between stable and unstable fatigue crack propagation during high temperature creep-fatigue in austenitic stainless steels is introduced. The transition from one class of behavior to the other is related to the precipitate distribution and to the nature of the prevailing crack path. It is shown by reference to new studies and examples drawn from the literature that this behavior is common to both high strain and predominantly elastic fatigue in austenitic stainless steels. The relevance of this distinction to a mechanistic approach to high temperature plant design is discussed.

Fatigue Crack Propagation Tests on 304 Stainless Steel in High Temperature Water: Accelerated Cracking Rates and Transition to Lower Rates

2004 ◽  
Author(s):  
G. L. Wire ◽  
W. M. Evans ◽  
W. J. Mills
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
High Temperature ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Hold Time ◽  
304 Stainless Steel ◽  
High Temperature Water ◽  
Stress Ratios ◽  
Temperature Water

Previous fatigue crack propagation (FCP) tests on a single heat of 304 stainless steel (304 SS) specimens showed a strong acceleration of rates in high temperature water with 40–60 cc H2/kg H2O at 288°C, with rates up to 20X the air rates. The accelerated rates were observed under fully reversed conditions (R = −1) (Wire and Mills, 2001) and high stress ratios (R = 0.7 and 0.83) (Evans and Wire, 2001). In this study, a second heat of 304 SS has been tested at 243°C and 288°C and lower positive stress ratios (R = 0.3, 0.5). The second heat showed the large acceleration of rates at 288°C observed previously. Rates were up to two times lower at 243°C, but were still 7–8X the air rates. A time-based correlation successfully correlates the accelerated rates observed, and is nearly identical to fits of literature data in hydrogen water chemistry (HWC), which has hydrogen added at a lower level of about 1 cc/kg H2O. The accelerated rates on the second heat were not stable under two different test conditions. In contrast to the first heat, the second heat showed a reduction in environmental enhancement at long rise times, accompanied by a change in fracture mode. Addition of a constant load hold time of 1200 s between cycles also caused a marked reduction in crack propagation rates in both heats, with reduction to nearly air rates in the second heat. The differing rise time effects between the two heats could be rationalized by time-dependent deformation. More hold time testing is required to define the material and loading conditions which lead to reduced rates.

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