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Title: Effect of Chemistry Variations in Plate and Weld Filler Metal on the Corrosion Performance of Ni-Cr-Mo Alloys

Abstract

The ASTM standard B 575 provides the requirements for the chemical composition of Nickel-Chromium-Molybdenum (Ni-Cr-Mo) alloys such as Alloy 22 (N06022) and Alloy 686 (N06686). The compositions of each element are given in a range. For example, the content of Mo is specified from 12.5 to 14.5 weight percent for Alloy 22 and from 15.0 to 17.0 weight percent for Alloy 686. It was important to determine how the corrosion rate of welded plates of Alloy 22 using Alloy 686 weld filler metal would change if heats of these alloys were prepared using several variations in the composition of the elements even though still in the range specified in B 575. All the material used in this report were especially prepared at Allegheny Ludlum Co. Seven heats of plate were welded with seven heats of wire. Immersion corrosion tests were conducted in a boiling solution of sulfuric acid plus ferric sulfate (ASTM G 28 A) using both as-welded (ASW) coupons and solution heat-treated (SHT) coupons. Results show that the corrosion rate was not affected by the chemistry of the materials in the range of the standards.

Authors:
;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
894778
Report Number(s):
UCRL-PROC-218703
TRN: US200702%%331
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: Presented at: 2006 ASME Pressure Vessels and Piping Conference, Vancouver, Canada, Jul 23 - Jul 27, 2006
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALLOYS; BOILING; CHEMICAL COMPOSITION; CHEMISTRY; CORROSION; FILLER METALS; PERFORMANCE; PLATES; PRESSURE VESSELS; SULFATES; SULFURIC ACID

Citation Formats

Fix, D V, and Rebak, R B. Effect of Chemistry Variations in Plate and Weld Filler Metal on the Corrosion Performance of Ni-Cr-Mo Alloys. United States: N. p., 2006. Web.
Fix, D V, & Rebak, R B. Effect of Chemistry Variations in Plate and Weld Filler Metal on the Corrosion Performance of Ni-Cr-Mo Alloys. United States.
Fix, D V, and Rebak, R B. Sun . "Effect of Chemistry Variations in Plate and Weld Filler Metal on the Corrosion Performance of Ni-Cr-Mo Alloys". United States. doi:. https://www.osti.gov/servlets/purl/894778.
@article{osti_894778,
title = {Effect of Chemistry Variations in Plate and Weld Filler Metal on the Corrosion Performance of Ni-Cr-Mo Alloys},
author = {Fix, D V and Rebak, R B},
abstractNote = {The ASTM standard B 575 provides the requirements for the chemical composition of Nickel-Chromium-Molybdenum (Ni-Cr-Mo) alloys such as Alloy 22 (N06022) and Alloy 686 (N06686). The compositions of each element are given in a range. For example, the content of Mo is specified from 12.5 to 14.5 weight percent for Alloy 22 and from 15.0 to 17.0 weight percent for Alloy 686. It was important to determine how the corrosion rate of welded plates of Alloy 22 using Alloy 686 weld filler metal would change if heats of these alloys were prepared using several variations in the composition of the elements even though still in the range specified in B 575. All the material used in this report were especially prepared at Allegheny Ludlum Co. Seven heats of plate were welded with seven heats of wire. Immersion corrosion tests were conducted in a boiling solution of sulfuric acid plus ferric sulfate (ASTM G 28 A) using both as-welded (ASW) coupons and solution heat-treated (SHT) coupons. Results show that the corrosion rate was not affected by the chemistry of the materials in the range of the standards.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Feb 05 00:00:00 EST 2006},
month = {Sun Feb 05 00:00:00 EST 2006}
}

Conference:
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  • The ASTM standard B 575 provides the requirements for the chemical composition of Nickel-Chromium-Molybdenum (Ni-Cr-Mo) alloys such as Alloy 22 (N06022) and Alloy 686 (N06686). The compositions of each element are given in a range. For example, the content of Mo is specified from 12.5 to 14.5 weight percent for Alloy 22 and from 15.0 to 17.0 weight percent for Alloy 686. It was important to determine how the corrosion rate of welded plates of Alloy 22 using Alloy 686 weld filler metal would change if heats of these alloys were prepared using several variations in the composition of themore » elements even though still in the range specified in B 575. All the material used in this report were especially prepared at Allegheny Ludlum Co. Seven heats of plate were welded with seven heats of wire. Immersion corrosion tests were conducted in a boiling solution of sulfuric acid plus ferric sulfate (ASTM G 28 A) using both as-welded (ASW) coupons and solution heat-treated (SHT) coupons. Results show that the corrosion rate was not affected by the chemistry of the materials in the range of the standards.« less
  • The ASTM standard B 575 provides the requirements for the chemical composition of Nickel-Chromium-Molybdenum (Ni-Cr-Mo) alloys such as Alloy 22 (N06022) and Alloy 686 (N06686). The compositions of each element are given in a range. For example, the content of Mo is specified from 12.5 to 14.5 weight percent for Alloy 22 and from 15.0 to 17.0 weight percent for Alloy 686. It was important to determine how the corrosion rate of welded plates of Alloy 22 using Alloy 686 weld filler metal would change if heats of these alloys were prepared using several variations in the composition of themore » elements even though still in the range specified in B 575. Seven heats of plate were welded with seven heats of wire. Immersion corrosion tests were conducted in a boiling solution of sulfuric acid plus ferric sulfate (ASTM G 28 A) using both as-welded (ASW) coupons and solution heat-treated (SHT) coupons. Results show that the corrosion rate was not affected by the chemistry of the materials in the range specified in the standard B 575.« less
  • The ASTM standard B 575 provides the requirements for the chemical composition of Nickel-Chromium-Molybdenum (Ni-Cr-Mo) alloys such as Alloy 22 (N06022) and Alloy 686 (N06686). The compositions of each element are given in a range. For example, the content of Mo is specified from 12.5 to 14.5 weight percent for Alloy 22 and from 15.0 to 17.0 weight percent for Alloy 686. It was important to determine how the corrosion rate of welded plates of Alloy 22 using Alloy 686 weld filler metal would change if heats of these alloys were prepared using several variations in the composition of themore » elements even though still in the range specified in B 575. All the material used in this report were especially prepared at Allegheny Ludlum Co. Seven heats of plate were welded with seven heats of wire. Immersion corrosion tests were conducted in a boiling solution of sulfuric acid plus ferric sulfate (ASTM G 28 A) using both as-welded (ASW) coupons and solution heat-treated (SHT) coupons. Results show that the corrosion rate was not affected by the chemistry of the materials within the range of the standards.« less
  • The effects of ozonated seawater on the corrosion behavior of Ni-Cr-Mo alloys C-276, C-22, 625 and 59 were studied and the results were compared with those obtained for aerated solutions. Corrosion rates and crevice corrosion information obtained from plate samples at intervals of 2, 4, 8, 16, 26, and 47 weeks were compared with electrochemical measurements of corrosion potential, linear polarization resistance (LPR), and cyclic polarization curves from concurrently immersed wire samples. It was observed that samples in ozonated seawater, in general, exhibited higher corrosion rates (5--34 {micro}m/yr), as measured by both LPR and weight change measurements, than those exposedmore » to aerated seawater. These relatively low corrosion rates were accompanied by the precipitation of voluminous amounts of black flocculent corrosion product in the ozonated solution, identified as hydrated nickel chlorates formed from dissolved nickel ions in solution. The only adherent corrosion product observed on samples in ozonated solutions is characterized by the presence of a thin oxide film exhibiting interference coloration, which varied from alloy to alloy, and with time of exposure. Creviced samples of alloy C-276 in ozonated seawater showed preferential corrosion at the interface between creviced and uncreviced surfaces, with the creviced surface being completely protected, in contrast to slight pitting damage observed in the crevice region of samples exposured to aerated seawater. Cyclic polarization curves of alloys C-276 and C-22 also suggested increased crevice corrosion susceptibility in ozonated seawater, as indicated by the presence of a hysteresis loop and an increase in the passive current density compared to those observed in aerated seawater.« less
  • Susceptibility to stress corrosion cracking (SCC) of candidate materials for the inner container of the multi-barrier nuclear waste package was evaluated by using wedge-loaded precracked double- cantilever-beam (DCB) specimens in deaerated acidic brine (pH at 2.70) at 90{degrees}C. Materials tested include Alloys 825, G-30, C-4, 625 and C-22; and Ti Grade- 12. Duplicate specimen of each material was loaded at different initial stress intensity factor (K) values ranging between 23 and 46 ksi/in. Both metallography and compliance method were used to determine the final crack length. The final stress intensity for SCC (K{sup ISCC}) was computed from the measured finalmore » wedge load and the average crack length. The results indicate that in general, the final crack length measured by metallography and compliance was very close to each other, thus, providing very similar K{sup ISCC} values. While tests are still ongoing, the preliminary results suggest that, compared to other five alloys tested, Alloy 825 may exhibit the maximum tendency to SCC.« less