Sensitization of high-nitrogen austenitic stainless steels by dichromium nitride precipitation.

Details

• Personal Author:
  Atteridge DG ; Rawers JC ; Simmons JW
• Description:
  High-nitrogen (N) stainless steels (SS) are receiving increased attention because of their strength advantages over carbon (C)-alloyed materials, but they have been found susceptible to dichromium nitride (Cr2N) precipitation during thermal exposure between approx. 600 degrees C and 1,050 degrees C. Sensitization susceptibility of a high-N, low-C austenitic SS by Cr2N precipitation at 700 degrees C and 900 degrees C was determined using the single-loop electrochemical potentiokinetic reactivation (EPR) test. High-N SS was found susceptible to sensitization caused by grain boundary (GB) precipitation of Cr2N, with the degree of sensitization increasing systematically with aging time at 700 degrees C. Sensitization of high-N materials did not require the concomitant precipitation of chromium (Cr)-rich metal carbide (M23C6). Materials aged at 900 degrees C were not sensitized, although the rate of precipitation was greater than at 700 degrees C. This indicated the minimum Cr level in the Cr-depleted zone of the matrix associated with nitride precipitation at 900 degrees C was higher than required to produce attack in the EPR test. Prior deformation accelerated Cr2N precipitation and sensitization kinetics at 700 degrees C, in accordance with previous research on C-based alloys. Sensitization development and deformation effects in high-N austenitic SS as a result of Cr-rich Cr2N precipitation were qualitatively analogous to sensitization phenomena ascribed to Cr-rich M23C6 precipitation in C-based alloys. Results indicated high-N, low-C SS was susceptible to intergranular corrosion (IGC) and/or intergranular stress corrosion cracking (IGSCC) as a result of sensitization after thermal exposure to a temperature regime at which Cr2N precipitation occurs. [Description provided by NIOSH]
• Subjects:
  Metals Occupational Health Safety Temperature
• Keywords:
  Stainless steel; Metal alloys; Electrochemical properties; Thermal effects; Temperature effects; Materials testing
• Series:
  Mining Publications
• ISSN:
  0010-9312
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  Oregon ; OSHA Region 10
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  ALRC - Albany Research Center
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  491-501
• Volume:
  50
• Issue:
  7
• NIOSHTIC Number:
  nn:10012427
• Citation:
  Corrosion 1994 Jul; 50(7):491-501
• Federal Fiscal Year:
  1994
• Peer Reviewed:
  True
• Source Full Name:
  Corrosion
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:7dc847c09aedf140bc731323e8446b4703641ae07d6ad9e7b7238120dab30b8f7dcaa9b938d34d035f87873a0fe7fec262d5d13dcaf290925445e82b6de3b57d
• Download URL:
  https://stacks.cdc.gov/view/cdc/247009/cdc_247009_DS1.pdf
• File Type:
  [PDF - 168.02 KB ]