Microstructures and mechanical properties of duplex low carbon steel

3rd International Conference on Science, Technology, and Interdisciplinary Research

自然科学;工业技术

Alfirano^1 ; Eben, U.S.^1 ; Hidayat, M.^2

Department of Metallurgical Engineering, Faculty of Engineering, University of Sultan Ageng Tirtayasa, Cilegon

42435, Indonesia^1

Iron Making Division, PT. Krakatau Posco, Cilegon

42435, Indonesia^2

关键词: Annealing temperatures;    Automotive applications;    Intercritical annealing;    Intercritical annealing temperatures;    Martensite volume fraction;    Microstructures and mechanical properties;    Optimal annealing;    Transformation kinetics;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/344/1/012001/pdf
DOI  :  10.1088/1757-899X/344/1/012001

来源: IOP

【 摘 要 】

The microstructures behavior of duplex cold-rolled low carbon steel for automotive applications has been investigated. Intercritical annealing treatment is commonly used to develop a duplex low carbon steel containing ferrite and martensite. To get a duplex phase ferrite and martensite, the specimens were heated at inter-critical annealing temperature of 775°C - 825°C, for heating time up to 20 minutes, followed by water-quenched. The hardness of specimens was studied. The optical microscopy was used to analyze the microstructures. The optimal annealing conditions (martensite volume fraction approaching 20%) at 775°C with a heating time of 10 minutes was achieved. The highest hardness value was obtained in cold-rolled specimens of 41% in size reduction for intercritical annealing temperature of 825°C. In this condition, the hardness value was 373 HVN. The correlation between intercritical annealing temperature and time can be expressed in the transformation kinetics as fγ/fe = 1-exp(-Ktn) wherein K and n are grain growth rate constant and Avrami's exponent, respectively. From experiment, the value of K = 0.15 and n = 0.461. Using the relationship between temperatures and heating time, activation energy (Q) can be calculated that is 267 kJ/mol.