Effects of alloying elements upon austenite decomposition in low-C steels

Journal Article · Fri Jul 01 04:00:00 EDT 1994 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

DOI:https://doi.org/10.1007/BF02665470· OSTI ID:7278315

Chen, J K; Reynolds, Jr, W T ^[1]; Vandermeer, R A ^[2]

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1. Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Materials Science and Engineering Dept.
2. Physical Metallurgy, Washington, DC (United States). Naval Research Lab.

The kinetics of austenite decomposition were studied in high-purity Fe-O.1C-0.4Mn-0.3Si-X (concentrations in weight percent; X represents 3Ni, 1Cr, or 0.5Mo) steels at temperatures between 500 C and 675 C. The transformation stasis phenomenon was found in the Fe-C-Mn-Si-Mo and Fe-C-Mn-Si-Ni alloys isothermally transformed at 650 C and 675 C but not in the Fe-C-Mn-Si and Fe-C-Mn-Si-Cr alloys at any of the temperatures investigated. The occurrence of transformation stasis was explained by synergistic interactions among alloying elements. The paraequilibrium model was applied to calculate the metastable fraction of ferrite in each alloy. This fraction was shown to coincide with cessation of transformation in the Mo alloy transformed at 600 C. Transformation stasis was found in both the Ni and the Mo alloys isothermally reacted at 650 C and 675 C. The interactions among Mn, Si, and Mo, as well as interactions among Mn, Si, and Ni, appear to decrease the threshold concentrations for transformation stasis in Fe-C-Mn-Si systems. Segregation of Mn and Mo to the [alpha]/[gamma] boundary, assisted by the presence of Si, was suggested to enhance the solute draglike effect (SDLE) and lead to transformation stasis. In the Ni alloy, a lower driving force for ferrite formation resulting from the Ni addition could be responsible for the occurrence of transformation stasis.

• OSTI ID: 7278315
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Journal Name: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States) Vol. 25:7; ISSN 0360-2133; ISSN MTTABN
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
AUSTENITE
CARBON ADDITIONS
CHROMIUM ALLOYS
CRYSTAL-PHASE TRANSFORMATIONS
IRON ALLOYS
IRON BASE ALLOYS
LOW ALLOY STEELS
MANGANESE ADDITIONS
MANGANESE ALLOYS
METALLURGICAL EFFECTS
MOLYBDENUM ADDITIONS
MOLYBDENUM ALLOYS
NICKEL ALLOYS
PHASE STUDIES
PHASE TRANSFORMATIONS
SILICON ADDITIONS
SILICON ALLOYS
STEELS