Materials for Generator Retaining Rings

1981 ◽  
Vol 103 (4) ◽  
pp. 267-275 ◽  
Author(s):  
R. Viswanathan
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
State Of The Art ◽  
Corrosion Cracking ◽  
Safe Operation

Retaining rings are among the highest stressed components of electricial generators, whose integrity is critical to the reliable and safe operation of the generators. The steel currently used for this application is susceptible to stress corrosion cracking and is also limited by yield strength to about 1200 MPa. The use of alternate materials with improved mechanical properties can enhance the reliability, efficiency, size capability and availability of generators. This paper is a state-of-the-art review of the materials technology pertaining to retaining rings.

Relationships Between Electrochemical Measurements and Stress Corrosion Cracking of Maraging Steel

CORROSION ◽  
1967 ◽  
Vol 23 (1) ◽  
pp. 5-10 ◽  
Author(s):  
J. A. S. GREEN ◽  
E. G. HANEY
Keyword(s):  
Yield Strength ◽  
Stress Corrosion ◽  
Maraging Steel ◽  
Stress Corrosion Cracking ◽  
Electrode Potential ◽  
Full Range ◽  
Corrosion Cracking ◽  
Deionized Water ◽  
Failure Times ◽  
Ph Values

Abstract Stress corrosion cracking of 18Ni maraging steel foil has been studied in deionized water solutions with the pH adjusted by NaOH additions over a range from 8 to 13. The full range of NaCl contents from saturated solutions to no addition was tested with specimens stressed to 75 percent of yield strength. For each variation in NaCl content, the specimen failure times go through a minimum with respect to pH. With increasing NaCl content, the minimum becomes more pronounced and its position shifts towards higher pH values. The position of each minimum is indicated by electrode potential measurements. Potentiostatic measurements as a function of pH confirm that maximum susceptibility to stress corrosion cracking occurs just prior to the onset of passivation.

About the Role of Hydrogen in Stress Corrosion Cracking of a 7xxx Aluminium Alloy (Al-Zn-Mg)

2016 ◽  
Vol 877 ◽  
pp. 522-529 ◽  
Author(s):  
Loïc Oger ◽  
Eric Andrieu ◽  
Grégory Odemer ◽  
Lionel Peguet ◽  
Christine Blanc
Keyword(s):  
Mechanical Properties ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Local Stress ◽  
Corrosion Cracking ◽  
Hydrogen Trapping ◽  
Stress Tests ◽  
Fracture Modes ◽  
Cracking Mechanisms ◽  
Local Stress State

The effects of hydrogen during stress corrosion cracking mechanisms (SCC) have been highlighted for many years but hydrogen trapping mechanisms are not yet well understood for 7xxx aluminium alloys. The 7046-T4 Al-Zn-Mg alloy has been chosen for this study because its low corrosion susceptibility allows hydrogen embrittlement (HE) to be more easily distinguished during SCC tests. Tensile stress tests have been carried out at a strain rate of 10-3 s-1 on tensile samples after an exposure at their corrosion potential in a 0.6M chloride solution for 165 hours under an imposed loading of 80%Rp0.2. The results were compared to those obtained for samples pre-corroded without mechanical loading applied and healthy specimens. A loss of mechanical properties was observed for the pre-corroded samples and presumably attributed to the absorption, the diffusion and the trapping of hydrogen which affects a volume under the surface of the alloy and modifies its mechanical properties. Scanning electron microscope (SEM) observations highlighted a strong effect of hydrogen on fracture modes. The ductile-intergranular initial fracture mode observed on the healthy samples was partially replaced for the pre-corroded samples by a combination of two main fracture modes, i.e. brittle intergranular and cleavage, in relation with the nature of the hydrogen trapping sites and local stress state.

Effect of three-stage homogenization on mechanical properties and stress corrosion cracking of Al-Zn-Mg-Zr alloys

2016 ◽  
Vol 675 ◽  
pp. 280-288 ◽  
Author(s):  
Tao Xiao ◽  
Yunlai Deng ◽  
Lingying Ye ◽  
Huaqiang Lin ◽  
Chaojun Shan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Zr Alloys

Effect of Thermal Aging on the Stress Corrosion Cracking Sensitivity of Z3CN20.09M Stainless Steel

2020 ◽  
Vol 993 ◽  
pp. 474-481
Author(s):  
Huan Chun Wu ◽  
Wen Xin Ti ◽  
Cheng Tao Li ◽  
Ze Jie Zhu ◽  
Fa He Cao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Solution Ph ◽  
High Temperature Water ◽  
Hcl Solution ◽  
Electrochemical Microscopy ◽  
Temperature Water

The stress corrosion cracking (SCC) sensitivity of aged Z3CN20.09M stainless steel (SS) was investigated by scanning electrochemical microscopy (SECM), nanoindenter and slow strain rate tensiometer (SSRT). The results indicated that the hardness and modulus of the samples increased with increasing aging time at 475 °C, which increased about 80% and 15% respectively after aging for 1000h. After immersed in NaCl+HCl solution (pH=2) for 7 h, the pitting corrosion point appeared of specimen aged for 1000h. While it was not found even for 24 h of as-received (AR) and aged for 500 h specimens at the same condition. The SCC sensitivity was increased about one time of the specimen aged for 1000 h tested in 300 °C high temperature water. The combined effect associated the embrittlement of mechanical properties and the decrease of corrosion resistance is regarded as the main reason for the increasing of SCC sensitivity.

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