Thermodynamic Calculations of Carbonitrides in V-Ti-N Microalloyed Steels for Non-Quenched and Tempered Oil Well Tubes
Abstract:
Precipitation behaviors of carbonitrides in a V-Ti-N microalloyed steel for non-quenched and tempered seamless oil well tubes were calculated by the equilibrium principle of a three-phase miscibility gap including the austenite and two carbonitrides. The thermodynamic calculations indicate that the precipitates first formed at 1473C are TiN particles, subsequently some of them formed at high temperatures maintain the chemistry down to low temperatures, the others gradually transform to complex (TixV1-x )(CyN1-y) carbonitrides. In addition, the precipitates formed at 846C are V- and C-rich V(CxN1-x) carbonitrides. The formation sequence is verified by experimental data. These results are more consistent with the viewpoint that, the precipitation behavior of vanadium in austenite matrix below 800oC in medium-carbon V-bearing microalloyedsteels plays a great role in controlling the decomposition of austenite.
Keywords:
microalloyed non-quenched/tempered steel, precipitation, carbonitrides, thermodynamics.
Author:
WANG An-dong (l,3), LID Guo-quan (1), LID Sheng-xinl, YANG Cai-fu (2), LI Chang-rong (1), XIANG Song (1), HAN Qing-li (1)
Affiiation
(1) School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
(2) Institute for Structural Materials, Central Iron & Steel Research Institute, Beijing 100081, China.
(3) School of Materials Science and Engineering, Jiangsu University, Zhenjiang Jiangsu 212013, China.
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Source:
Iron and Steel, Vol. 40, 2005, pp. 283-291. (Vanitec Publication - V1105-7)
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