Authors: Naoki Maruyama, T. Ogawa, M. Takahashi
Abstract: Subgrain growth in deformed ferrite and incomplete recrystallisation during intercritical
annealing in low carbon (LC) steels was investigated by EBSD and FEGTEM/EDS. It was
confirmed that fine dual phase (α+γ) microstructures could be obtained even without the addition of
microalloying elements such as Nb and Ti, if the steels were heated above Ac1 temperature before
the completion of primary recrystallisation and then intercritically annealed. The fine microstructure
was found to be mainly due to the inhibition of primary recrystallisation, and also due to the
inhibition of subgrain growth in deformed matrix by finely dispersed γ phase formed during
heating. Mn segregation at α/γ interfaces seems to indicate that the kinetics of boundary migration
in the existence of γ is controlled by the volume diffusion of substitutional alloying elements across
the α/γ interfaces.
247
Authors: Xin Li Song, Ze Xi Yuan, Juan Jia, Li Xia Fan, Ping He Li
Abstract: The development of texture and grain boundary character are researched for a boron bearing IF steel after recrystallization annealing for different times at 810°C. The results show that the main texture components are {111}<110> and {111}<112> after the cold rolling samples annealing different times. The maximal volume fraction of <111>//ND texture is about 78% for the sample annealing for 120sec. The main CSL boundaries are ∑3，∑5，∑7，∑9，∑11，∑13b and ∑17b. And the ∑3 grain boundary increase with increasing the annealing times from 60sec to 180sec.
243
Authors: Yong Jun Lan, C. Pinna
Abstract: The Plane Strain Compression and Static Recrystallisation Textures of BCC Metals Have Been Simulated Using a Coupled 3D Crystal Plasticity Finite Element (CPFE)-Single Phase Field (PF) Model Using an Interstitial-Free (IF) Steel as an Example. the Recrystallisation Nucleation Is Modelled Based on the Orientation Dependent Recovery (ODR) Theory which Assumes that Deformation Texture Components with a Relatively High Number of Slip Systems Activated during the Plane Strain Compression Undergo a Faster Recovery Process during the Subsequent Annealing due to the Cross Slip of Dislocations and as a Result Will Nucleate Earlier than Others. the Growth of Strain-Free Grains Is Simulated Using the Mis-Orientation Angle Dependent Grain Boundary Energy and Interface Mobility. A Linear Interpolation Method Is Adopted to Map the Data between the CPFE Model of Deformation and the Single PF Model of Recrystallisation. Simulated Results Show a Qualitative Agreement with the Typical Rolling and Annealing Textures Measured Experimentally for BCC Metals. Apart from the Texture and Grain Structure Formed during Deformation and Annealing, the Softening Fraction Can Also Be Simulated Using the Developed Model.
3040
Authors: Olga Sukhopar, Günter Gottstein
Abstract: In the present study, a modified cellular automaton CORe (Cellular Operator for Recrystallization) was used to predict the recrystallization (RX) texture and microstructure of 70% cold rolled commercial AA8079L alloy at 300°C. The nucleation of the Cube orientation is of considerable scientific interest since the Cube texture component influences significantly the anisotropy of material properties. Experimental data collected during this investigation were used for subsequent modeling. By studying the annealed material by EBSD, an average nucleation rate at Cube bands was established and used in the model. The simulated microstructure reveals, in general, good agreement with experiment. The texture prediction shows the right tendency, but the modeled intensity of the Cube texture is about 2 times smaller than in experiment.
455
Authors: Yong Yang, Bin Wang, Zhao Dong Wang, Yan Mei Li, Guo Dong Wang, R.D.K. Misra
Abstract: Nanoscale cementite can be obtained in 0.17% carbon steel during isothermal treatment at 500oC after ultra fast cooling (UFC) and thermo-mechanical treatment. The precipitation strengthening contribution to yield strength was more than 250 MPa, when the heat treatment time was less than 20 min. The carbon diffusion is impacted by Mn and Si, which are redistributed during the precipitation process. All the effects induced by substitutional elements can be manifested through the restricted carbon diffusion, which is equal to the carbon diffusion multiplied by adjustable parameters. Based on this, a kinetic model has been adapted to simulate the precipitation behaviors of cementite involving the evolution of the number density per unit volume, radius of cementite over time, and the evolution of carbon concentration in matrix. An excellent agreement in mean radius of particles between the predictions of the model and experimental observations was obtained. It was found that the nucleation period of cementite was very short and did not exceed 0.2 s, and there was an overlap between the nucleation period and the growth period, and the coarsening period began at about 1s. In the growth stage, the carbon concentration in the matrix dropped rapidly and the mean radius of particles increased quickly. In the coarsening stage, the carbon concentration remained unchanged and the number of particles per unit volume fell sharply.
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