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Title: A SYNCHROTRON DIFFRACTION STUDY OF TRANSFORMATION BEHAVIOUR IN 9 CR STEELS USING SIMULATED WELD HEAT-AFFECTED ZONE CONDITIONS

Abstract

Synchrotron diffraction experiments were conducted to examine the real-time transformation behaviours of an ex-perimental 9Cr-3W-3Co-NbV steel with high B and low N (N130B), and the commercial P92 steel under simulated weld heat-affected zone thermal cycles. When heated to peak temperatures near 1100 C, both steels rapidly trans-formed from ferrite to 100% austenite. During cooling, both transformed to martensite near 400 C. Both steels also retained untransformed austenite: 1.7% in N130B, and 5.8% in P92. The N130B was also heated to about 60 C above its A3 of 847 C. About 56% of the original ferrite never transformed to austenite. During cooling an additional 21% of ferrite and 23% of martensite formed. It retained no austenite. The P92 was heated to just above its A3 of 889 C. About 15% of the original ferrite never transformed to austenite. During cooling an additional 22% of ferrite and 60% of martensite formed. This steel retained about 2.3% austenite. Metallographic examina-tions indicated that the M23C6 in N130B was much more stable than that in P92 for heating to the lower peak tem-peratures. Analysis using equilibrium thermodynamics suggested that the more stable M23C6 in N130B could raise its apparent A3 by sequestering C. This couldmore » cause the ferrite-austenite transformation to appear sluggish. Ther-modynamic analysis also indicated that the M23C6 in N130B contained about 3.9 at% B compared to about 0.08 at% B in that of P92. In contrast, the refractory metal element content of the M23C6 was predicted to be higher in P92.« less

Authors:
 [1];  [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Shared Research Equipment Collaborative Research Center
Sponsoring Org.:
FE USDOE - Office of Fossil Energy (FE)
OSTI Identifier:
981759
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: 7th International Charles Parsons Turbine Conference, Glasgow, United Kingdom, 20070911, 20070913
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 43 PARTICLE ACCELERATORS; AUSTENITE; DIFFRACTION; FERRITE; HEATING; MARTENSITE; REFRACTORY METALS; STEELS; SYNCHROTRONS; THERMODYNAMICS; TRANSFORMATIONS; TURBINES; 9Cr steel; boron; heat-affected zone; phase transformations; Type IV failure

Citation Formats

Santella, Michael L, Specht, Eliot D, Shingledecker, John P, and Abe, Fujio. A SYNCHROTRON DIFFRACTION STUDY OF TRANSFORMATION BEHAVIOUR IN 9 CR STEELS USING SIMULATED WELD HEAT-AFFECTED ZONE CONDITIONS. United States: N. p., 2007. Web.
Santella, Michael L, Specht, Eliot D, Shingledecker, John P, & Abe, Fujio. A SYNCHROTRON DIFFRACTION STUDY OF TRANSFORMATION BEHAVIOUR IN 9 CR STEELS USING SIMULATED WELD HEAT-AFFECTED ZONE CONDITIONS. United States.
Santella, Michael L, Specht, Eliot D, Shingledecker, John P, and Abe, Fujio. Mon . "A SYNCHROTRON DIFFRACTION STUDY OF TRANSFORMATION BEHAVIOUR IN 9 CR STEELS USING SIMULATED WELD HEAT-AFFECTED ZONE CONDITIONS". United States. doi:.
@article{osti_981759,
title = {A SYNCHROTRON DIFFRACTION STUDY OF TRANSFORMATION BEHAVIOUR IN 9 CR STEELS USING SIMULATED WELD HEAT-AFFECTED ZONE CONDITIONS},
author = {Santella, Michael L and Specht, Eliot D and Shingledecker, John P and Abe, Fujio},
abstractNote = {Synchrotron diffraction experiments were conducted to examine the real-time transformation behaviours of an ex-perimental 9Cr-3W-3Co-NbV steel with high B and low N (N130B), and the commercial P92 steel under simulated weld heat-affected zone thermal cycles. When heated to peak temperatures near 1100 C, both steels rapidly trans-formed from ferrite to 100% austenite. During cooling, both transformed to martensite near 400 C. Both steels also retained untransformed austenite: 1.7% in N130B, and 5.8% in P92. The N130B was also heated to about 60 C above its A3 of 847 C. About 56% of the original ferrite never transformed to austenite. During cooling an additional 21% of ferrite and 23% of martensite formed. It retained no austenite. The P92 was heated to just above its A3 of 889 C. About 15% of the original ferrite never transformed to austenite. During cooling an additional 22% of ferrite and 60% of martensite formed. This steel retained about 2.3% austenite. Metallographic examina-tions indicated that the M23C6 in N130B was much more stable than that in P92 for heating to the lower peak tem-peratures. Analysis using equilibrium thermodynamics suggested that the more stable M23C6 in N130B could raise its apparent A3 by sequestering C. This could cause the ferrite-austenite transformation to appear sluggish. Ther-modynamic analysis also indicated that the M23C6 in N130B contained about 3.9 at% B compared to about 0.08 at% B in that of P92. In contrast, the refractory metal element content of the M23C6 was predicted to be higher in P92.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

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