Abstract
The thermal deformation and precipitation behavior at 900-1100° and strain rate of 0.1-5s−1 were studied by Gleeble-3800 thermal simulator of Q1030 high strength steel. The activation energy of hot deformation in austenite region was determined by regression method, and the hot deformation equation of the Q1030 high strength steel was established. The critical strain and peak strain of dynamic recrystallization were predicted accurately by fitting the inflection point with cubic polynomial of curve of Q1030 high strength steel, and relationship between critical strain and Z parameter was established. Finally, the precipitation behavior of Nb and Ti particles during low strain rate deformation was studied, the results show that the precipitated phases in steel are rectangular TiN, quadratic (Nb, Ti) (C, N) carbonitride, elliptical (Nb, Ti) C carbide and NbC. Thermodynamic calculation shows that the order of precipitation of the second phase in steel is TiN, TiC, NbC and NbN.
Highlights
Since the 1970s, the development of low-alloy high-strength steel in the world has entered a new period
When deformation occurs at high temperatures and high strain rates, the changes in the internal tissues of the metal are very complex, including hardening, dynamic recovery, and dynamic crystallization of austenite during deformation
The precipitation behavior of Nb and Ti nitrogen carbides at low strain rate is studied by TEM and EDX, and the theoretical basis is provided for the establishment of a reasonable hot working process
Summary
Since the 1970s, the development of low-alloy high-strength steel in the world has entered a new period. In the control rolling stage, steel is used to undergo large-scale downward deformation in the austenite recrystallization area, and tiny austenite recrystallized grains are obtained., The deformation is carried out in the austenite non-recrystallization area, resulting in a large number of deformation bands inside the grains These deformation bands and austenite grain boundaries can provide nucleating points for controlling the phase transition of the cooling process. When deformation occurs at high temperatures and high strain rates, the changes in the internal tissues of the metal are very complex, including hardening, dynamic recovery, and dynamic crystallization of austenite during deformation. These behaviors are important factors that determine. The precipitation behavior of Nb and Ti nitrogen carbides at low strain rate is studied by TEM and EDX, and the theoretical basis is provided for the establishment of a reasonable hot working process
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