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

Journal Article · Fri Jul 01 00:00:00 EDT 1994 · Corrosion (Houston); (United States)

DOI:https://doi.org/10.5006/1.3294349· OSTI ID:7229765

Simmons, J W; Atteridge, D G ^[1]; Rawers, J C ^[2]

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1. Oregon Graduate Inst. of Science and Technology, Beaverton, OR (United States)
2. Bureau of Mines, Albany, OR (United States). Albany Research Center

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 (Cr[sub 2]N) precipitation during thermal exposure between [approximately]600 C and 1,050 C. Sensitization susceptibility of a high-N, low-C austenitic SS by Cr[sub 2]N precipitation at 700 C and 900 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 Cr[sub 2]N, with the degree of sensitization increasing systematically with aging time at 700 C. Sensitization of high-N materials did not require the concomitant precipitation of chromium (Cr)-rich metal carbide (M[sub 23]C[sub 6]). Materials aged at 900 C were not sensitized, although the rate of precipitation was greater than at 700 C. This indicated the minimum Cr level in the Cr-depleted zone of the matrix associated with nitride precipitation at 900 C was higher than required to produce attack in the EPR test. Prior deformation accelerated Cr[sub 2]N precipitation and sensitization kinetics at 700 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 Cr[sub 2]N precipitation were qualitatively analogous to sensitization phenomena ascribed to Cr-rich M[sub 23]C[sub 6] 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 Cr[sub 2]N precipitation occurs.

• OSTI ID: 7229765
• Journal Information: Corrosion (Houston); (United States), Vol. 50:7; ISSN 0010-9312
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM NITRIDES
PRECIPITATION
STAINLESS STEELS
INTERGRANULAR CORROSION
PRECIPITATION HARDENING
STRESS CORROSION
CHROMIUM CARBIDES
CRACK PROPAGATION
HEAT TREATMENTS
NITROGEN ADDITIONS
ALLOYS
CARBIDES
CARBON COMPOUNDS
CHEMICAL REACTIONS
CHROMIUM COMPOUNDS
CORROSION
HARDENING
HIGH ALLOY STEELS
IRON ALLOYS
IRON BASE ALLOYS
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
SEPARATION PROCESSES
STEELS
TRANSITION ELEMENT COMPOUNDS
360100* - Metals & Alloys