Influence of inductive heating on microstructure and material properties in roll forming processes

Guk, Anna; Kunke, Andreas; Kräusel, Verena; Landgrebe, Dirk

doi:10.1063/1.5008107

“…Since the different temperature regions were formed on the steel blank after localized induction heating and after the results of differential strength regions related to the temperature regions were also obtained, the reasons for the generation of these results were then explored. As reported, the start (A C1 )–finish (A C3 ) temperatures rise with the increasing heating rates according to the TTA-diagram of 22MnB5 steel (Time-Temperature-Austenization) [13] and the A C1 and A C3 at the heating rate of 100 K·s −1 correspond to 750 and 900 °C, respectively [14]. In detail, the heating rate 100 K·s −1 corresponds before reaching T C , and the rate after T C is 10 K·s −1 .…”

Section: Discussionmentioning

confidence: 93%

“…After reaching Tc, the heating rate decreases and is nearly constant for two experiments with values ranging from 7.5 to 8.3 K·s −1 . This is because, due to the magnetic properties of steel, the heating rate cannot be further raised once the material is paramagnetic [14]. However, the oxide is unevenly distributed on the surface of the uncoated steel blank and the small oxide points are sporadically distributed on the blank, which suggest the oxide may noticeably affect the judgment of temperature distribution of the blank.…”

Section: Resultsmentioning

confidence: 99%

Research on a New Localized Induction Heating Process for Hot Stamping Steel Blanks

Bao

¹

,

Chen

²

,

Li

³

et al. 2019

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Localized induction heating with one magnetizer was experimentally analyzed in order to investigate the altering effect of the magnetizer on the magnetic field. A 22MnB5 blank for tailored property was locally heated to produce the parts of a car body in white, such as the B-pillars. A lower-temperature region with a temperature in the two-phase zone and a full-austenitic high-temperature region were formed on the steel blank after 30 s. After water-quenching, the mixture microstructure (F + M) and 100% fine-grained lath martensite were obtained from the lower- and high-temperature regions, respectively. Moreover, the ultimate tensile stress (UTS) of the parts from the lower- and high-temperature regions was 977 and 1698 MPa, respectively, whereas the total elongations were 17.5% and 14.5%, respectively. Compared with the parts obtained by conventional furnace heating–water quenching (UTS: 1554 MPa, total elongation: 12%), the as-quenched phase developed a tensile strength over 100 MPa greater and a higher ductility. Thus, the new heating process can be a good foundation in subsequent experiments to arbitrarily tailor the designable low-strength zone with a higher ductility by using magnetizers.

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“…Thus, the range of relevant rates was set between 500 K s -1 and 2500 K s -1 . The inductive heating is described for heating rates up to 150 K s -1 in [14,15]. The reported data does not cover the relevant heating rate range.…”

Section: Austenite Formation During Inductive Heatingmentioning

confidence: 99%

Manufacturing and Virtual Design to Tailor the Properties of Boron-Alloyed Steel Tubes

Hordych

¹

,

Herbst

²

,

Nürnberger

³

et al. 2020

Virtual Design and Validation

2

0

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Application of products with properties locally adapted for specific loads and requirements has become widespread in recent decades. In the present study, an innovative approach to manufacture tubes with tailored properties in the longitudinal direction from a boron-alloyed steel 22MnB5 was developed. Due to advanced heating and cooling strategies, a wide spectrum of possible steel phase compositions can be obtained in tubes manufactured in a conventional tube forming line. A heat-treatment station placed after the forming line is composed of an inductive heating and an adapted water-air cooling spray system. These short-action processes allow fast austenitizing and subsequent austenite decomposition within several seconds. To describe the effect of high inductive heating rates on austenite formation, dilatometric investigations were performed in a heating rate range from 500 K s-1 to 2500 K s-1. A completed austenitizing was observed for the whole range of the investigated heating rates. The austenitizing was described using Johnson-Mehl-Avrami model. Furthermore, series of experiments on heating and cooling with different cooling rates in the developed technology line was carried out. Complex microstructures were obtained for the cooling in still as well as with compressed air, while the water-air cooling at different pressures resulted in quenched martensitic microstructures. Nondestructive testing of the mechanical properties and the phase composition was realized by means of magnetization measurements. Logarithmic models to predict the phase composition and hardness values from the magnetic properties were obtained. Subsequently, a simulation model allowing virtual design of tubes in the FE-software ANSYS was developed on basis of experimental data. The model is suited to predict microstructural and mechanical properties under consideration of the actual process parameters.

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“…The feed rate was limited by the plasma welding in the processing line. In order to accelerate the diffusion, the target austenitizing temperature was set at a value of 1150 °C, which is above the temperature of the homogenous austenite at the highest heating rates in literature [14]. Thus, the range of relevant rates was set between 500 K s -1 and 2500 K s -1 .…”

Section: Austenite Formation During Inductive Heatingmentioning

confidence: 99%

Virtual Design and Validation

Rubio¹,

Chamoin²,

Louf³

2020

Lecture Notes in Applied and Computational Mechanics

0

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Application of products with properties locally adapted for specific loads and requirements has become widespread in recent decades. In the present study, an innovative approach to manufacture tubes with tailored properties in the longitudinal direction from a boron-alloyed steel 22MnB5 was developed. Due to advanced heating and cooling strategies, a wide spectrum of possible steel phase compositions can be obtained in tubes manufactured in a conventional tube forming line. A heat-treatment station placed after the forming line is composed of an inductive heating and an adapted water-air cooling spray system. These short-action processes allow fast austenitizing and subsequent austenite decomposition within several seconds. To describe the effect of high inductive heating rates on austenite formation, dilatometric investigations were performed in a heating rate range from 500 K s-1 to 2500 K s-1. A completed austenitizing was observed for the whole range of the investigated heating rates. The austenitizing was described using Johnson-Mehl-Avrami model. Furthermore, series of experiments on heating and cooling with different cooling rates in the developed technology line was carried out. Complex microstructures were obtained for the cooling in still as well as with compressed air, while the water-air cooling at different pressures resulted in quenched martensitic microstructures. Nondestructive testing of the mechanical properties and the phase composition was realized by means of magnetization measurements. Logarithmic models to predict the phase composition and hardness values from the magnetic properties were obtained. Subsequently, a simulation model allowing virtual design of tubes in the FE-software ANSYS was developed on basis of experimental data. The model is suited to predict microstructural and mechanical properties under consideration of the actual process parameters.

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Influence of inductive heating on microstructure and material properties in roll forming processes

Cited by 4 publications

References 3 publications

Research on a New Localized Induction Heating Process for Hot Stamping Steel Blanks

Research on a New Localized Induction Heating Process for Hot Stamping Steel Blanks

Manufacturing and Virtual Design to Tailor the Properties of Boron-Alloyed Steel Tubes

Virtual Design and Validation

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