Dilatometric study of continuous cooling transformation of intercritical austenite in cold rolled AHSS-DP steels

Costa, Patricia Sheilla; Altamirano-Guerrero, Gerardo; Salinas‐Rodríguez, Armando; Salas-Reyes, Antonio Enrique; Goodwin, Frank

doi:10.1016/j.jmrt.2022.06.140

Cited by 9 publications

(4 citation statements)

References 31 publications

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“…During the pause in water cooling, austenite adjacent to the phase boundary with ferrite is enriched in carbon by diffusion from ferrite, while the interior of austenite grains, due to the slow diffusion of carbon in austenite, is poorer in carbon. This results in different hardenability of austenite grains across their volume [7]. Poorer in carbon austenite interiors undergo bainitic transformation, while richer grain margins undergo martensitic transformation.…”

Section: Shaping the Dual Phase Microstructurementioning

confidence: 99%

Characteristic of DP600 Steel Produced in Hot Rolling Process

Kaźmierski,

Krawczyk,

Frocisz

2023

Archives of Metallurgy and Materials

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CharaCteristiC of DP600 steel ProDuCeD in hot rolling ProCess DP600 steels are characterized by a dual phase ferritic-martensitic microstructure, to which they owe their exceptionally favourable combination of high strength and good ductility. one of the production methods for this grade of steel is the hot rolling process. Despite the fact that these steels have been produced on an industrial scale for almost 40 years, they are still being studied intensively, with new research on the formation of their microstructure and properties published every year. This article focuses on the characteristics of DP600 steel produced on a hot rolling mill for applications in automotive industry. The article presents the results of mechanical properties tests and microstructure analysis of DP600 steel obtained in an industrial hot rolling process. The general characteristic of DP600 steel presented in this article, is supplemented with statistical analysis of correlations between chemical composition, selected process parameters and mechanical properties of hot rolled DP600 steel.

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Section: Shaping the Dual Phase Microstructurementioning

confidence: 99%

Characteristic of DP600 Steel Produced in Hot Rolling Process

Kaźmierski,

Krawczyk,

Frocisz

2023

Archives of Metallurgy and Materials

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“…process, causing cracking and wrinkling of the material, which limits the application of AHSS in the body (Soleimani et al, 2020;Costa et al, 2022;Zhang and Xu, 2022).…”

Section: Introductionmentioning

confidence: 99%

Impact of various heat treatment processes and welding speeds on the mechanical properties and microstructures of soft/hard composite joints

Yu,

Wang,

Chen

et al. 2024

Front. Mater.

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There is a certain contradiction between the formability and strength of auto parts. In this work, the whole-process processing technology of hot stamping soft steel was designed, and 500 MPa grade mild steel (500HS) with uniform microstructure was prepared. To take into account the strength and formability of hot stamping soft steel, here, based on laser welding technology, 500 MPa grade soft steel, and 1500 MPa grade hard steel are benignly composited, and by adjusting the laser welding speed and heat treatment process, the loss of mechanical properties caused by the weld seam is eliminated. A soft/hard composite steel for automobiles with excellent strength, ductility and formability is obtained. To maintain excellent deformation resistance and bonding force of the weld, the heat-affected zone of 500HS retains part of bainite and pearlite, which is beneficial to the strain compatibility and stress partitioning with the microstructure of the base metal, and the hardness is low. After heat treatment, which helps to transfer the stress concentration effect to the 500HS base metal with strong energy absorption capacity, so that the clad steel has excellent comprehensive mechanical properties. This process is developed based on existing industrialized equipment and has broad application prospects.

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“…[6][7][8][9][10][11] Intercritical annealing in the two-phase temperature range of austenite-ferrite, followed by fast cooling to room temperature to change austenite to martensite, can produce a DP microstructure in cold-rolled DP steels. Costa et al [5] revealed that the temperature of martensite-start transformation depends on the cooling rate, particularly when intercritical austenitization and slow cooling rate conditions coincide. Also, Bräutigam-Matus et al [4] reported that carbon enrichment of intercritical γ as a result of heating in the ferrite-austenite region and carbon partitioning during the formation of proeutectoid ferrite on cooling remarkably alters the character of subsequent austenite-phase transformations.…”

Section: Introductionmentioning

confidence: 99%

“…In the recent decade, there has been a surge in technical and scientific interest in dual-phase (DP) steel, one of the oldest and most well-known instances of AHSS. [1][2][3][4][5] Continuous yielding behavior, high elongation, a low yield stress-to-tensile strength ratio, and a high work hardening rate are all features of DP steels. [6][7][8][9][10][11] Intercritical annealing in the two-phase temperature range of austenite-ferrite, followed by fast cooling to room temperature to change austenite to martensite, can produce a DP microstructure in cold-rolled DP steels.…”

Section: Introductionmentioning

confidence: 99%

Effect of Intercritical Annealing Time on the Microstructure and Mechanical Properties of Dual‐Phase Steel Processed by Large‐Strain Asymmetric Cold‐Rolling

Khorasani

Jamaati

Aval

2023

steel research int.

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Herein, the effect of intercritical annealing time on the microstructure and mechanical properties of dual‐phase steel processed by large‐strain asymmetric cold‐rolling is studied. It is observed that the martensite islands are uniformly distributed in the ferrite phase in the microstructures of dual‐phase steels due to performing the asymmetric cold‐rolling before intercritical annealing treatment. As the intercritical annealing time increases up to 10 min, the fraction of martensite increases. By increasing the holding time and fraction of martensite, the carbon content of the martensite phase is decreased. The short‐term intercritical annealing eliminates the yield point phenomenon. However, intercritical annealing at 860 °C for 20 min leads to the reoccurrence of a yield point phenomenon. Increasing the intercritical annealing time to 10 min improves the yield strength to 505 MPa and ultimate tensile strength to 834 MPa. However, the strength decreases sharply after the holding time of 20 min. There is a perfect linear relationship between the mechanical properties and the fraction of martensite. Ductile failure is observed at the center of the fracture surfaces of dual‐phase steels while shear failure occurs at the edges of the fracture surfaces.

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Dilatometric study of continuous cooling transformation of intercritical austenite in cold rolled AHSS-DP steels

Cited by 9 publications

References 31 publications

Characteristic of DP600 Steel Produced in Hot Rolling Process

Characteristic of DP600 Steel Produced in Hot Rolling Process

Impact of various heat treatment processes and welding speeds on the mechanical properties and microstructures of soft/hard composite joints

Effect of Intercritical Annealing Time on the Microstructure and Mechanical Properties of Dual‐Phase Steel Processed by Large‐Strain Asymmetric Cold‐Rolling

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