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Your search keyword '"Liu, Lizhong"' showing total 3 results
Start Over Author "Liu, Lizhong" Topic microstructure
3 results on '"Liu, Lizhong"'

1. Numerical prediction of microstructure and mechanical properties for the S-rail with tailored properties.

Author

Lu, Shouzhao, Liu, Lizhong, Hu, Ping, Shen, Guozhe, Gao, Junzhe, and Huo, Xiaobo

Subjects
*STEEL, *PREDICTION models, *FOIL stamping, *MICROSTRUCTURE, *MARTENSITIC transformations, *MECHANICAL properties of metals, *AUSTENITE
Abstract

Hot stamped parts are applied widely to reduce the weight and meet safety requirements for new vehicles. It has been noticed, however, that hot stamped parts of fully martensitic transformation lead to a low elongation of about 5%. Hot stamped parts may be enhanced by locally tailoring their mechanical properties to improve their energy absorption. And partially heated dies offer a method for decreasing the cooling rate of blank located in hot region to obtain the hot stamped parts with tailored properties. In this paper, an S-Rail die was separated into three sections. The middle part of the die was heated and other parts maintained room temperature during the hot stamping process. The blank of 22MnB5 boron steel was stamped by this S-Rail die. A numerical model was established to simulate the stamping process. The microstructure and mechanical properties of blank located in the hot region and cold region were investigated. At the hot region temperature of 500°, the variation of Vickers hardness through the S-Rail bottom and side wall was investigated. The austenite decomposition curves in hot region and cold region were also given to reveal the difference of phase transformations. [ABSTRACT FROM AUTHOR]

Published
2013
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2. Investigations on numerical simulation of tailored tempering process based on related experiments.

Author

Deng, Siying, Shen, Guozhe, Hu, Ping, Liu, Lizhong, and Ying, Liang

Subjects
TEMPERING, COMPUTER simulation, MICROSTRUCTURE, MECHANICAL behavior of materials, STRENGTH of materials, DUCTILITY, PERFORMANCE evaluation
Abstract

Tailored tempering process is a strategy to get functional optimized components by controlling cooling rate. Since cooling rate determines the final microstructure and mechanical property, the components with tailored properties can benefit from the regions of low strength and increased ductility for crash performance. In this paper, the influences of time-temperature profiles and hardness are investigated by adjusting tool temperatures with numerical simulation method. The range of air gap between the heated and cooled region is also under discussion. By comparison of the simulation and experimental results, the effectiveness of numerical simulation can be verified and the reasons causing the error are analyzed. [ABSTRACT FROM AUTHOR]

Published
2013
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3. A Tensile Specimen of Tailor Rolled Blanks with Equal Probability in Yield and Its Mechanical Behavior Analysis.

Author

Zhang, Sijia, Liu, Xianghua, and Liu, Lizhong

Subjects
MICROSTRUCTURE, DIGITAL image processing, STRAINS & stresses (Mechanics), FINITE element method, TENSILE tests
Abstract

In this paper, the microstructure and mechanical properties that distribute regulation along the rolling direction of tailor rolled blanks (TRB) were investigated. A tensile specimen with equal probability in yield (EYS) was first designed considering variation both in thickness and in material strength. The uniaxial tension test was carried out with a digital image correlation method to analyze the mechanical behaviors. The results showed that the strain distribution of EYS was homogeneous. From the results, it can be known that a new design philosophy for a TRB tensile specimen is reasonable and EYS is suitable to characterize the mechanical behavior of TRB. The true stress-strain curves of metal in different cross sections of TRB were calculated. On the basis of the true stress-strain curves, a material model of TRB was constructed and then implemented into finite element simulations of TRB uniaxial tensile tests. The strain distribution of numerical and experimental results was similar and the error between the elongation of the specimen after fracture obtained by experiment and FE ranged from 9.51% to 13.06%. Therefore, the simulation results match well with the experimental results and the material model has high accuracy and as well as practicability. [ABSTRACT FROM AUTHOR]

Published
2018
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