Phase transformation temperatures and Fe enrichment of a 22MnB5 Zn-Fe coated steel under hot stamping conditions

Ximenes, Daniel Alexandre da Costa; Moreira, Luciano Pessanha; Carvalho, José Eduardo Ribeiro de; Leite, Duílio Norberto Ferronatto; Toledo, Reginaldo Gomes; Dias, Fabio Moreira da Silva

doi:10.1016/j.jmrt.2019.11.003

Cited by 22 publications

(4 citation statements)

References 9 publications

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“…The zone beside the ICHAZ is the UCHAZ (zone "c"), where the temperature is well above the Ac3 temperature line called the fusion line (zone "b"); therefore, complete austenitization occurred. The fully austenitized microstructure was retransformed into a martensitic structure because of the high cooling rate involved in the RSW process, including FL and FZ (zone "a") 19 In their extensive study, Ximenes et al 20 investigated the influence of heating rate on the transformation temperatures Ac1 and Ac3 of 22MnB5 steel sheets coated with Zn-Fe (GA). Their findings suggest that these temperatures have an impact on the microstructures of the steel, which is likely to be observed in various areas of resistance spot welding.…”

Section: Resultsmentioning

confidence: 99%

Study of Patchwelded Blanks Resistance Spot Welding (RSW) Before Hot Stamping with and without Heat Treatment Parameters

Lara,

Abbade,

Mucsi

et al. 2023

Mat. Res.

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In recent years, increasing automotive safety and energy efficiency has become a major concern in the automotive industry. Advanced high-strength steel (AHSS) was chosen for its weight reduction and high mechanical strength for the body in white (BIW). Specifically, it has been used in 22MnB5 steel press hardening type steel (PHS) with patchweld technology, which enables the production of reinforced and structural parts in a single stroke during the hot forming process. This study aimed to evaluate the resistance spot welding parameters for patchweld before hot stamping, considering the minimum and maximum residual stress, while ensuring a welding nugget diameter within the approved range. Microhardness and X-ray diffraction were used to analyze the welding zones for phase identification and residual stress measurements. After five weeks of elapsed time, the spot weld showed cracks that were not seen immediately after welding and were probably due to a high residual stress state.

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Section: Resultsmentioning

confidence: 99%

Study of Patchwelded Blanks Resistance Spot Welding (RSW) Before Hot Stamping with and without Heat Treatment Parameters

Lara,

Abbade,

Mucsi

et al. 2023

Mat. Res.

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“…OM images with applied strain rate of 0.01 s −1 at various deformation temperatures are shown in Figure 6, obtained from the gauge center (position 1) and the area near fracture surface (position 2). For 22MnB5 boron steel, the transformation temperature of eutectoid reaction (Ac1) is ~740 °C, and the phase transformation onset temperature from austenite to ferrite (Ac3) is ~860 °C [28,29].For 22MnB5 boron steel, the temperature of eutectoid reaction point (Ac1) is ~740 °C, and the beginning temperature of phase transition from austenite to ferrite (Ac3) is ~860 °C [28,29]. In the present work, the samples were austenitized at 950 °C for180 s before thermal tensile tests, and the following cooling rate 30 °C/s was higher than the critical quenching rate;therefore,bainite transition occurred when stretched at 500 °C.…”

Section: Microstructure Evolutionmentioning

confidence: 99%

“…OM images with applied strain rate of 0.01 s −1 at various deformation temperatures are shown in Figure 6, obtained from the gauge center (position 1) and the area near fracture surface (position 2). For 22MnB5 boron steel, the transformation temperature of eutectoid reaction (A c1 ) is ~740 • C, and the phase transformation onset temperature from austenite to ferrite (A c3 ) is ~860 • C [28,29]. In the present work, the samples were austenitized at 950 • C for 180 s before thermal tensile tests, and the following cooling rate 30 • C/s was higher than the critical quenching rate; therefore, bainite transition occurred when stretched at 500 • C. As shown in Figure 6a,b, a large number of bainites accompanied with ferrites and some pearlites are detected.…”

Section: Microstructure Evolutionmentioning

confidence: 99%

Stress Response Behavior, Microstructure Evolution and Constitutive Modeling of 22MnB5 Boron Steel under Isothermal Tensile Load

Zhou

Guo

Feng

2022

Metals

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22MnB5 boron steel has become one of the main choices for lightweight vehicles due to its extremely high mechanical properties. To explore the intrinsic relationship between the thermoforming process and thermo-mechanical behavior for constitutive modeling and thermoforming of vehicle structure, thermal tensile tests in wide ranges of deformation temperature (500 °C to 950 °C) and strain rate (0.01 s−1 to 10 s−1) were performed using aGleeble-1500D thermal simulator with hot-rolled 22MnB5 boron steel. With increasing applied strain and strain rate, the flow stress increases gradually and then tends to saturation after reaching peak stress, except for that at 0.01 s−1 and 500 °C. With increasing deformation temperature, the microstructure transforms from a mixture of bainite, ferrite and pearlite to lath-shaped martensite accompanied with some residual austenite. At 950 °C, the average size of martensite decreases with increasing applied strain rate. After thermoforming with austenitizing temperature of 950 °C, lath-shaped martensite accompanied with some residual austenite isobtained in a thermoformed U-shaped structural part, resulting in a dramatical increase in tensile strength. In contrast, the tensile strength of sidewall is slightly higher than that of bottom. Based on the Arrhenius-type constitutive model, a modified constitutive model is constructed with a relative error of less than 5%, which can well describe the flow stress behavior of the studied 22MnB5 boron steel.

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“…The best-known representative is 22MnB5 steel which can produce a martensitic microstructure that is important for enhancing the side crash performance in B-pillar parts [7,8]. With 22MnB5 steel, it is necessary to reach a cooling rate of at least 27 • C/s, as shown in Figure 1, (possibly up to 30 • C/s) to gain martensitic microstructures [3,[9][10][11]. Hot stamping has a number of advantages over conventional stamping at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Study of Transition Areas in Press-Hardened Steels in a Combined Tool for Hot and Cold Forming

et al. 2023

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Press-hardening, also known as hot stamping, is a manufacturing process for producing car body parts that must meet the high demands of their mechanical properties and safety parameters. Moreover, these components often require different mechanical properties in different parts of the component. This work presents the press-hardening process in a special combined tool where one half of the tool is heated and the other half is cooled. The cooled part has been 3D printed due to the complexity of the internal cooling channels. The aim of this work is to investigate the variation of the microstructures in the sheet metal and the mechanical properties in relation to the cooling process in the tool and to determine the transition area where these properties cross over. Two steels were chosen for the experiment. The most commonly used steel 22MnB5, and an experimental high-strength steel with 0.2% C alloyed with manganese and aluminium. A temperature of 425 °C was set in the heated part of the tool, and different holding times in the tool were tested. In the heated part of the tool, a bainitic structure with a fraction of ferrite and retained austenite was formed, while in the quenched part of the tool, a martensitic transformation was promoted due to rapid cooling. In addition to microscopic analyses, mechanical tests and hardness measurements were also performed.

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Phase transformation temperatures and Fe enrichment of a 22MnB5 Zn-Fe coated steel under hot stamping conditions

Cited by 22 publications

References 9 publications

Study of Patchwelded Blanks Resistance Spot Welding (RSW) Before Hot Stamping with and without Heat Treatment Parameters

Study of Patchwelded Blanks Resistance Spot Welding (RSW) Before Hot Stamping with and without Heat Treatment Parameters

Stress Response Behavior, Microstructure Evolution and Constitutive Modeling of 22MnB5 Boron Steel under Isothermal Tensile Load

Study of Transition Areas in Press-Hardened Steels in a Combined Tool for Hot and Cold Forming

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