Austenite formation in 0.2% C and 0.45% C steels under conventional and ultrafast heating

Self Cite

The aim of the present work is to study the microstructure evolution of a cold‐rolled low carbon steel alloyed with Cr, Mn, Mo, and Nb during continuous heating. The formation of austenite and its further transformation is examined by means of peak annealing experiments at three different heating rates, followed by quenching. The effect of carbide‐forming alloying elements in the kinetics of austenite formation and decomposition is discussed with the aim of DICTRA calculations. Electron Probe Micro Analysis allows the detection of small compositional fluctuations within the microstructure, which are responsible for local changes in the mechanism of austenite formation. It is experimentally demonstrated that the temperature dependence of the austenite fraction is relatively insensitive to the heating rate. It is suggested that carbide‐forming alloying elements slow down the kinetics of austenite formation.

Section: Resultssupporting

confidence: 91%

Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Section: Data Post‐processing and Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

‘Flash’ Annealing in a Cold‐Rolled Low Carbon Steel Alloyed With Cr, Mn, Mo, and Nb: Part I ‐ Continuous Phase Transformations

Cerda

Vercruysse

Goulas

et al. 2018

Self Cite

The Effect of Heating Rate on the Microstructure of a Soft-Annealed Medium Carbon Steel

Papaefthymiou

Goulas

Cerda

et al. 2017

A comparative study on the microstructural changes after conventional (20 8C s À1 ) and ultrafast (300 8C s À1 ) heating is performed on a medium carbon steel in the soft annealed condition. Continuous-heating dilatometry experiments are carried out. The phase transformations and the volume phase fraction of austenite are determined among other microstructural changes. The microstructure is first observed using Optical Microscopy (OM), further characterized by Scanning (SEM), and detailed analyzed by Transmission Electron Microscopy (TEM). The effect of heating rate on the kinetics of cementite dissolution and austenite formation is rationalized. The experimental results are compared with Dictra calculations, and the possible effects on the kinetics of diffusion-controlled austenite formation are rationalized as well. Metallographic observations indirectly suggest the enhanced nucleation of austenite above A m .

“Flash” Annealing in a Cold‐Rolled Low Carbon Steel Alloyed with Cr, Mn, Mo, and Nb: Part II—Anisothermal Recrystallization and Transformation Textures

Cerda¹,

Kestens

Petrov

2018

Self Cite

The aim of the present investigation is to study the microstructure and texture evolution in a cold‐rolled low carbon steel subjected to continuous heating and subsequent quenching. Peak‐annealing and quenching experiments are carried out at different temperatures at three heating rates (10, 400, and 1000 °C s−1). The texture evolution in ferrite and martensite is analyzed separately via Electron Backscattered Diffraction (EBSD) measurements. It is observed that the recrystallization is virtually completed at 771 °C in samples heated at 10 °C s−1. Conversely, the recrystallization is suppressed in samples heated at rates ≥400 °C s−1. In samples heated at 10 °C s−1, the ferrite texture evolves according to the well‐known recrystallization behavior, showing a maximum in {113}<110> components, whereas in samples heated at rates ≥400 °C s−1, the texture is similar to the one of the cold‐rolled material. It is concluded that the texture evolution in martensite is strongly dependent on the evolution of recrystallization textures in ferrite. A particular grain substructure product of the interaction between the recrystallization of ferrite and massive austenite formation is observed after heating at rates ≥400 °C s−1. However, this substructure seems to have effect neither on the textures of ferrite nor on the work hardening behavior.