Effect of intercritical annealing temperature on multiphase microstructure evolution in ultra-low carbon medium manganese steel

In this study, a new Fe-6Mn-4Al-0.4C high strength medium manganese hot rolled steel sheet was designed. The influence mechanism of the intercritical annealing (IA) temperature on microstructure evolution and mechanical properties of experimental steel were studied by SEM and XRD. The experimental steel was held for 30 minutes at 640°C, 680°C, 720°C, 760°C, 800°C, respectively. When the annealing temperature was 640°C, cementite particles precipitated between the austenite and ferrite phase boundary. As the annealing temperature increased, the cementite gradually dissolved and disappeared, the fraction of lamellar austenite increased significantly. When the annealing temperature is 800°C, the coarse equiaxed austenite and ferrite appeared. The yield strength (YS) decreased, the product of strength and elongation (PSE) and total elongation (TE) both increased first and then decreased, while the ultimate tensile strength (UTS) showed the opposite trend. The experimental steel exhibited excellent comprehensive mechanical properties after held at 760°C for 30 min. The UTS was 870 MPa, the YS was 703 MPa, and the TE was 77 %, the PSE was 67 GPa·%.

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Tensile behavior of ultrafine-grained low carbon medium manganese steel by intercritical annealing treatment

Journal of Iron and Steel Research International ◽

10.1007/s42243-020-00405-0 ◽

2020 ◽

Vol 27 (12) ◽

pp. 1433-1445

Author(s):

Sohail Ahmad ◽

Zheng Han ◽

Li-ming Fu ◽

Huan-rong Wang ◽

Wei Wang ◽

...

Keyword(s):

Intercritical Annealing ◽

Annealing Treatment ◽

Tensile Behavior ◽

Manganese Steel ◽

Low Carbon ◽

Ultrafine Grained ◽

Medium Manganese Steel

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Effect of Intercritical Annealing Temperature and Holding Time on Microstructure and Mechanical Properties of Dual Phase Low Carbon Steel

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.493.721 ◽

2014 ◽

Vol 493 ◽

pp. 721-726 ◽

Cited By ~ 5

Author(s):

Alfirano ◽

Wibawa Samdan ◽

Hidayat Maulud

Keyword(s):

Carbon Steel ◽

Annealing Temperature ◽

Volume Fraction ◽

Intercritical Annealing ◽

Low Carbon Steel ◽

Growth Rate Constant ◽

Dual Phase ◽

Initial Condition ◽

Low Carbon ◽

Intercritical Annealing Temperature

Dual phase steels are an important advanced high strength steel, which have been widely used in the automotive industry for vehicle components requiring light weight and safety. In this study, the formation of dual phase structure with various volume fraction of martensite in a low carbon steel SS400 during intercritical annealing were investigated. It was found that intercritical annealing temperature and holding time affected the microstructure and mechanical properties of dual phase low carbon steel. The specimens were heated at intercritical annealing temperature of 750°C, 775°C, 800°C and 825°C, for holding periods of 6-18 minutes, followed by water quenching in order to get a dual phase ferrite and martensite. After quenching, it was obtained the optimal annealing conditions at 800°C with a holding periods of 10 minutes. In this condition, the tensile strength was increased up to 621 N/mm2or 39.24% higher than the initial condition, while the elongation decreased up to 13.8%. The hardness of specimens increased from 127.7 to 235.83 HVN or up to 84.67% higher than the initial condition. Meanwhile the volume fraction of martensite was 24.08%. The higher the temperature of the heating value of grain growth rate constant (K) increases. In addition, at the optimal poin, the value ofK(grain growth rate constant) andn(Avramis exponent) were 0.263 and 0.318, respectively, with activation energy (Q) of 3.98 J/mol.

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