Combination of Hot Forming with CRP and Rapid Cooling to Obtain Enhanced Formability in Thermomechanical Treatment

Birnbaum, Peter; Baumann, Markus; Kunke, Andreas; Kraeusel, Verena; Landgrebe, Dirk

doi:10.1557/adv.2017.179

Cited by 5 publications

(3 citation statements)

References 4 publications

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“…On the other hand, there may also be softening effects between the impacts. This mechanism was introduced for CRP of 22MnB5 by Birnbaum et al [14]. With help of the inclusion of additional investigation methods such as EBSD measurements, a better process understanding on the microscale could be achieved.…”

Section: Discussionmentioning

confidence: 99%

Improving the formability of magnesium by cushion-ram-pulsation

et al. 2018

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The application of forming processes using lightweight magnesium alloys is known to be difficult with regard to minor formability caused by a small number of active slip systems, especially at low temperatures. However, a new approach for deep drawing at elevated temperatures considers flexible motion profiles of a servo-screw press. The so-called cushion-ram-pulsation (CRP) is a newly developed method of position-controlled motion. As a result, the process limitations for deep drawing are significantly extended. This study investigates the deep drawing process of AZ31 cups by variable motion profiles of cushion and ram, focusing on enhanced drawability. Therefore the initial AZ31 sheet was fabricated by twin-roll casting. Furthermore, the adjustment of the forming temperature for an improved forming process and optimized component properties are described. In addition, the results were evaluated in comparison to conventional deep drawing, and the superior technological potential will be outlined.

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Section: Discussionmentioning

confidence: 99%

Improving the formability of magnesium by cushion-ram-pulsation

et al. 2018

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“…The curves of 𝑙𝑛𝜎 − 𝑙𝑛𝜀̇and 𝜎 − 𝑙𝑛𝜀̇are plotted based onEquations (7) and (8). Thereby, the parameter B can be determined by solving the slope of the curves.…”

Section: 𝑙𝑛𝜎 = 𝑙𝑛𝜀ṁmentioning

confidence: 99%

“…However, parts made by high-strength steels are difficult to form by cold stamping, and the resulting spring back is severe [6]. Stepwise thermoforming can effectively solve the above problem, and is considered to be the most suitable method for obtaining high-strength structural parts with complex shapes [7,8].…”

Section: Introductionmentioning

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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