Menu
Search
Filters
Close
Menu

Save 20% on select titles with code HIDDEN24 - Shop The Sale Now

Precursor Evolution and SCC Initiation of Cold-Worked Alloy 690 in Simulated PWR Primary Water

intergranular, stress corrosion cracking, crack initiation, UNS N06690, cold work, creep cavities, grain boundary microstructure
Available for download

Stress corrosion crack initiation of two thermally-treated, cold-worked UNS N06690 materials was investigated in 360 ºC simulated primary water using constant load tensile tests and blunt notch compact tension tests equipped with direct current potential drop for in-situ detection of cracking.

Product Number: 51317--9475-SG
ISBN: 9475 2017 CP
Author: Ziqing Zhai
Publication Date: 2017
Industries: Materials Selection and Design , Science of Corrosion
$0.00
$20.00
$20.00

Stress corrosion crack (SCC) initiation of two thermally-treated alloy 690 CRDM tubing heats in 21% and 31% cold-worked (CW) conditions have been investigated using constant load tensile tests (CLT) and blunt notch compact tension tests (BNT) in 360oC simulated primary water. All specimens were constantly monitored by direct current potential drop (DCPD) to detect the onset of cracking. SCC initiation was not detected by DCPD for the CLT specimens loaded at their yield stress for ~9220h however intergranular (IG) precursor damage and isolated surface cracks were observed on two of the 31%CW specimens. Some evidence for IG precursors was also discovered on the 21%CW CLT specimens without any significant crack nucleation. On the other hand crack initiation was detected by DCPD after ~11700h in the BNT specimens from the same two 31%CW CRDM materials loaded at moderate stress intensity. Blunt notch testing included a few slow loading ramps during the first 4000h before maintaining constant load for the remainder of the test. The BNT DCPD response for the 31%CW specimens resulted from significant IG crack nucleation and growth. On the contrary the 21%CW BNT specimens only exhibited isolated small IG surface cracks and showed no apparent DCPD change throughout the test. Interestingly post-test cross-section examination revealed many grain boundary nano-cavities in the bulk of all the specimens in both the CLT and BNT tests. The size and density of these cavities decrease as the cold-work level drops from 31% to 21%. Cavities were also found ahead of most IGSCC crack tips suggesting that the cavities are directly associated with SCC nucleation and possible growth processes. While the detailed characterizations performed on these grain boundary cavities are presented in a companion paper this current paper provides an overview of the test approach and quantitative assessments on cavity formation with regard to cold work level applied stress and exposure time. The role of these grain boundary cavities as precursors to IGSCC initiation will be discussed.

 

Key words: intergranular, stress corrosion cracking, crack initiation, UNS N06690, cold work, creep cavities, grain boundary microstructure

Stress corrosion crack (SCC) initiation of two thermally-treated alloy 690 CRDM tubing heats in 21% and 31% cold-worked (CW) conditions have been investigated using constant load tensile tests (CLT) and blunt notch compact tension tests (BNT) in 360oC simulated primary water. All specimens were constantly monitored by direct current potential drop (DCPD) to detect the onset of cracking. SCC initiation was not detected by DCPD for the CLT specimens loaded at their yield stress for ~9220h however intergranular (IG) precursor damage and isolated surface cracks were observed on two of the 31%CW specimens. Some evidence for IG precursors was also discovered on the 21%CW CLT specimens without any significant crack nucleation. On the other hand crack initiation was detected by DCPD after ~11700h in the BNT specimens from the same two 31%CW CRDM materials loaded at moderate stress intensity. Blunt notch testing included a few slow loading ramps during the first 4000h before maintaining constant load for the remainder of the test. The BNT DCPD response for the 31%CW specimens resulted from significant IG crack nucleation and growth. On the contrary the 21%CW BNT specimens only exhibited isolated small IG surface cracks and showed no apparent DCPD change throughout the test. Interestingly post-test cross-section examination revealed many grain boundary nano-cavities in the bulk of all the specimens in both the CLT and BNT tests. The size and density of these cavities decrease as the cold-work level drops from 31% to 21%. Cavities were also found ahead of most IGSCC crack tips suggesting that the cavities are directly associated with SCC nucleation and possible growth processes. While the detailed characterizations performed on these grain boundary cavities are presented in a companion paper this current paper provides an overview of the test approach and quantitative assessments on cavity formation with regard to cold work level applied stress and exposure time. The role of these grain boundary cavities as precursors to IGSCC initiation will be discussed.

 

Key words: intergranular, stress corrosion cracking, crack initiation, UNS N06690, cold work, creep cavities, grain boundary microstructure

Product tags
Also Purchased
Picture for Pitting Behavior of Lean Duplex Stainless Steels in Thiosulfate-Containing Paper Machine Environment
Available for download

Pitting Behavior of Lean Duplex Stainless Steels in Thiosulfate-Containing Paper Machine Environment

Product Number: 51317--9163-SG
ISBN: 9163 2017 CP
Author: Liang He
Publication Date: 2017
$20.00

This paper examined the pitting corrosion resistance of new grades of lean duplex stainless steels (LDSSs) UNS S32304, UNS S32003 and UNS S82441 in both chloride-only solution and thiosulfate containing simulated white water environments.
Picture for Optimization of the DL-EPR Method for Detecting Sensitization in Alloy 690
Available for download

Optimization of the DL-EPR Method for Detecting Sensitization in Alloy 690

Product Number: 51317--9037-SG
ISBN: 9037 2017 CP
Author: Mariano Kappes
Publication Date: 2017
$20.00

UNS N06690 is one of the current choices for nuclear power plant steam generator tubing. The objective of this work was the optimization of the double loop electrochemical potentiokinetic reactivation (DL-EPR) method for that alloy. Specimens were tested under different heat treatments.
Picture for Characterization of SCC Initiation Precursors in Cold-Worked Alloy 690
Available for download

51317--9717-Characterization of SCC Initiation Precursors in Cold-Worked Alloy 690

Product Number: 51317--9717-SG
ISBN: 9717 2017 CP
Author: Karen Kruska
Publication Date: 2017
$20.00

To evaluate the stress corrosion cracking initiation response of highly cold-worked UNS N06690, constant load tensile and blunt-notch compact tension testing were performed in 360°C simulated pressurized water reactor primary water.
Categories
Industry
Recently viewed
Popular tags
View all

Association for Materials Protection and Performance

© AMPP All Rights Reserved.
Membership Terms of Content Use
Contact Customer Support