Numerical modeling and experimental verification of ductile damage in boron steel hot stamping process

Hot stamping process has been regarded as one of the most attractive processes to produce high-strength parts with merits of low-forming load and small springback. However, the elongation of the hot-stamped parts is small, so the ability of crash resistance is limited. Recently, a novel hot stamping process integrated with quenching and partitioning treatment has been presented to improve the elongation of the final parts. In this article, the quenching and partitioning hot stamping process is further studied using the boron steel B1500HS, and the feasibility is verified by a series of quenching and partitioning tests followed by mechanical tests and microstructure observations. Moreover, an experimental tool for quenching and partitioning hot stamping process is first proposed in this article, where both air cooling device and heating system are designed, and a U-channel part is produced. Finally, in order to illustrate the active role of high elongation that the quenching and partitioning hot stamping process archived, numerical simulation of crash test for a B-pillar sample is conducted using finite element analysis software LS-DYNA.

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Prediction of Microstructure and Mechanical Properties in Hot Stamping

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1063.314 ◽

2014 ◽

Vol 1063 ◽

pp. 314-317

Author(s):

Chao Wang ◽

Bin Zhu ◽

Yi Lin Wang ◽

Yi Sheng Zhang

Keyword(s):

Phase Transformation ◽

Hot Stamping ◽

Fuel Efficiency ◽

Thin Sheet ◽

High Strength ◽

Transformation Model ◽

Boron Steel ◽

Stamping Process ◽

Improved Model ◽

Acceptable Agreement

Hot stamping process has been increasingly used in producing structural components of automobile to improve crash worthiness and fuel efficiency. Hot stamping process can produce ultimate tensile strength parts as high as 1500MPa. The high strength of hot –stamped components is attributed to the martensitic phase transformation which is transformed from austenite at elevated temperature. An improved model is developed based on Li’s phase transformation model to predict the austenite decomposition into ferrite, pearlite, bainite and martensite during arbitrary cooling paths for thin sheet boron steel. The simulated volume fractions and hardness profiles shows acceptable agreement to the corresponding experimental observations.

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Formability of aluminum-silicon coated boron steel in hot stamping process

Transactions of Nonferrous Metals Society of China ◽

10.1016/s1003-6326(14)63249-0 ◽

2014 ◽

Vol 24 (6) ◽

pp. 1750-1757 ◽

Cited By ~ 11

Author(s):

Zhong-xiang GUI ◽

Wei-kang LIANG ◽

Yi-sheng ZHANG

Keyword(s):

Hot Stamping ◽

Boron Steel ◽

Stamping Process ◽

Aluminum Silicon

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The influence of deformation history on microstructure and microhardness during the hot stamping process of boron steel B1500HS

International Journal of Materials and Product Technology ◽

10.1504/ijmpt.2013.058935 ◽

2013 ◽

Vol 46 (4) ◽

pp. 255 ◽

Cited By ~ 3

Author(s):

Bingtao Tang ◽

Qiaoling Wang ◽

Zhaoqing Wang ◽

Wei Zheng

Keyword(s):

Hot Stamping ◽

Boron Steel ◽

Deformation History ◽

Stamping Process

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Investigation of Hot Stamping Process of 22MnB5 Based on Metallo-Thermo-Mechanical Theory

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1063.251 ◽

2014 ◽

Vol 1063 ◽

pp. 251-256

Author(s):

Yong Gang Liu ◽

Yun Zhang ◽

Wu Zhang ◽

Jun Wan Li ◽

Hong Bin Wang ◽

...

Keyword(s):

Mechanical Properties ◽

Hot Stamping ◽

Boron Steel ◽

Coupling Theory ◽

Rockwell Hardness ◽

Fem Model ◽

Mechanical Coupling ◽

Stamping Process ◽

Cooling Behavior ◽

Good Agreement

In this study, based on the metallo-thermo-mechanical coupling theory, a FEM model of hot stamping including forming and quenching is built to investigate the cooling behavior and the microstructure evolution, and to predict the final mechanical properties of hot-stamped components. The results show that, after about 16s, the temperature of the entire component is lower than Mf of 22MnB5 boron steel and with a continuous uniform distribution. Most of austenite in component has transformed into martensite. To satisfy the required mechanical properties, the sufficient holding time of quenching in die is essential and it plays an important role in ensuring the required hardness. The predicted Rockwell hardness of component after hot stamping process is almost 512HV, which shows a good agreement with the experimental results. It implies that the metallo-thermo-mechanical numerical model established in this study is reasonable and reliable, which can provide a theoretical guidance for optimizing the hot stamping procedure.

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Indirect Hot Stamping of Boron Steel 22MnB5 for an Upper B-Pillar

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.314-316.703 ◽

2011 ◽

Vol 314-316 ◽

pp. 703-708

Author(s):

Jun Ying Min ◽

Jian Ping Lin ◽

Li Jiu Xin ◽

Jia Yue Li

Keyword(s):

Phase Transformation ◽

Cooling Rate ◽

Hot Stamping ◽

Tensile Tests ◽

Uniaxial Tensile ◽

Boron Steel ◽

Heating Process ◽

Air Cooling ◽

Stamping Process ◽

Vehicle Components

During the indirect hot stamping process of boron steel, the pre-deformed component undergoes air cooling, one-side-contact cooling and both-side-contact cooling phases successively. The effects of pre-deformation and cooling rate on the phase transformation should be understood before conducting indirect hot stamping experiments of vehicle components. Uniaxial tensile tests of boron steel at RT were carried out to obtain specimens with different pre-strain levels. Then they were heated to 900°C according to the indirect hot stamping process and quenching tests were performed on them at different cooling rates. Metallographic observations were performed on the quenched specimens and their hardness was measured. The results show that the pre-strain at RT has little influence on the phase transformation of boron steel. This is due to the dislocation structure introduced by deformation at RT recovered during the heating process and it is good for the indirect hot stamping. Upper B-pillar parts were first cold pre-formed, and then were heated and hot stamped. The microstructure and hardness results at different locations on the indirect hot stamped components are demonstrated qualified.

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