Investigation of forming parameters on springback for ultra high strength steel considering Young’s modulus variation in cold roll forming

Liu, Xiaoli; Cao, Jian; Chai, Xue-ting; Liu, Jiang; Zhao, Rongguo; Kong, Ning

doi:10.1016/j.jmapro.2017.08.001

Cited by 45 publications

(22 citation statements)

References 32 publications

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“…Ultra-high strength steel met the requirements of automobile safety performance and lightweight development in recent years, which has been widely used in automobile parts manufacturing [4,5]. However, the deformation ability of ultra-high strength steel at room temperature is very poor, and it is easy to produce forming quality defects such as cracking and springback [6,7]. Meanwhile, new challenges have been encountered in the design of key collision structures for automobiles: different yield strength needs to be designed in different positions, such as the A-pillar, B-pillar and C-pillar, to withstand the pressure of the roof, high strength and rigidity in the upper side, while to protect the safety of the occupants when the car is in a side collision, high shaping and toughness are required in the lower side [8].…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation and Multi-Objective Optimization of Partition Cooling in Hot Stamping of the Automotive B-Pillar Based on RSM and NSGA-II

Cui

Wang

et al. 2020

Metals

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In this study, the simulation and optimization of the partition cooling in the hot stamping process was carried out for an automotive B-pillar through minimizing the maximum thickening rate and the maximum thinning rate located in the rapid and slow cooling zones. The optimization was implemented by investigating the process parameters such as friction coefficient, sheet austenitizing temperature, holding time, heating zone temperature, the upper binder force and the lower binder force. The optimal Latin hypercube design (OLHD), the response surface methodology (RSM) and the non-dominated sorting genetic algorithm (NSGA-II) were combined to establish the relationship between process parameters and form quality objectives. After multi-objective optimization, the maximum thickening rate and the maximum thinning rate of the slow cooling zone and rapid cooling zone were 11.1% and 12.4%, 4.7% and 7.1%, respectively. Afterwards, the simulation was performed according to the optimized parameter combinations to analyze the temperature field, microstructure, tensile strength, hardness, thickening rate and thinning rate, and forming quality. Moreover, the hot stamping test and experimental results showed that the microstructure of the ferrite and pearlite structure was uniformly distributed in the slow cooling zone, and its tensile strength reached 680 MPa, the elongation was 11.4% and the hardness was 230.56 HV, while the lath martensite structure was obtained in the rapid cooling zone, with tensile strength of up to 1390 MPa, elongation of about 7.0% and hardness reaching 478.78 HV. The results of thickness, microstructure, tensile strength and the hardness test correspond well with the simulation results.

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Section: Introductionmentioning

confidence: 99%

Numerical Simulation and Multi-Objective Optimization of Partition Cooling in Hot Stamping of the Automotive B-Pillar Based on RSM and NSGA-II

Cui

Wang

et al. 2020

Metals

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“…Hysteresis occurs during reloading, and this phenomenon becomes more obvious with the increase of true strain. It has been proved that the theory of nonlinear elastic modulus can significantly improve the springback prediction accuracy of non-pre-notched metal strip in CRF process [21]. However, it is not clear whether the nonlinear elastic modulus can improve the prediction accuracy of springback in the hole region.…”

Section: Fea Simulation Model 41 Variable Elastic Modulus Mathematmentioning

confidence: 99%

“…Jaebong et al [20] established an elastoplastic material constitutive model to explain and describe the anisotropic elastic-plastic behavior of dual phase (DP) steel strip. Liu et al [21] discussed the influence of forming parameters on the springback of UHSS when considering the change of Young's modulus in CRF process. The results showed that the precision of springback prediction can be significantly improved by introducing variable elastic modulus into the finite element model.…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical investigation of the effect of holes on the springback in cold roll forming of UHSS

Liu

Pan

liu

et al. 2021

Preprint

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Ultra-high strength steel (UHSS) pre-notched sections are getting growing popularity in the automotive industry with the development of automotive lightweight. However, the springback of UHSS products is large, and the existence of holes also has an effect on the springback. Accurate prediction of springback of UHSS pre-notched products in cold roll forming ( CRF ) is a key issue to be solved. In this paper, the effect of holes on the springback of UHSS in CRF is discussed by simulation and experiment. The finite element model of pre-notched car threshold was constructed, and its accuracy was validated by continuous CRF experiment. The mathematical model of variable elastic modulus determined by tensile tests of martensite (MS) 1300 was applied in finite element model. The accuracy of springback was improved by 15% in the hole region by using variable elastic modulus . Several forming schemes were designed to research the effect of different features on the springback in the hole region. The results show that the existence of holes reduces the springback and the effect is different at different positions of the car threshold. The springback in the hole region decreases with the increase of the number of stands, the strip thickness and the hole diameter, and with the decrease of the distance between stands and the distance between holes. This study provides a help for reducing the influence of holes on the springback and improving the forming precision of pre-notched sections in the actual production of CRF.

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“…Besides, the material properties estimation, such as mechanical properties and the plastic anisotropy for the metal forming process, was not carried out in detail using the DIC technique in previously published articles. Therefore, there is still a research gap for further improvement in the cold roll forming process concerning the proper material properties estimation [ 32 , 33 , 34 , 35 ] and selecting proper forming parameters [ 11 , 12 , 36 ] for the chosen material to manufacture the quality parts without shape defects.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Investigation of AA5052-H32 Al Alloy with U-Profile in Cold Roll Forming

2021

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The cold roll forming process is broadly used to produce a specific shape of cold-roll formed products for their applications in automobiles, aerospace, shipbuilding, and construction sectors. Moreover, a proper selection of strip thickness and forming speed to avoid fracture is most important for manufacturing a quality product. This research aims to investigate the presence of longitudinal bow, the reason behind flange height deviation, spring-back, and identification of thinning location in the cold roll-forming of symmetrical short U-profile sheets. A room temperature tensile test is performed for the commercially available AA5052–H32 Al alloy sheets using Digital Image Correlation (DIC) technique, which allows complete displacement and strain data information at each time-step. The material properties are estimated from the digital images using correlation software for tested samples; the plastic strain ratios are also calculated from samples at 0°, 45°, and 90° to the rolling direction. The tested sample’s surface morphology and the elemental analysis are conducted using scanning electron microscopy (SEM) method and energy-dispersive X-ray spectroscopy (EDS) analytical technique combined with element mapping analysis, respectively. The cold roll forming experiments are systematically carried out, and then finite element analysis is utilized to correlate the experiment with the model. The performed cold roll forming numerical model outcome indicates a good agreement with the experimental measurements. Overall, the presented longitudinal strain was observed to influence the geometry profile. The spring-back is also noticed at the profile tail end and is more pronounced at high forming speed with lower strip thickness. Conversely, while the forming speed is varied, the strain and stress variations are observed to be insignificant, and the similar results also are recognized for the thinning behavior.

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Investigation of forming parameters on springback for ultra high strength steel considering Young’s modulus variation in cold roll forming

Cited by 45 publications

References 32 publications

Numerical Simulation and Multi-Objective Optimization of Partition Cooling in Hot Stamping of the Automotive B-Pillar Based on RSM and NSGA-II

Numerical Simulation and Multi-Objective Optimization of Partition Cooling in Hot Stamping of the Automotive B-Pillar Based on RSM and NSGA-II

Experimental and numerical investigation of the effect of holes on the springback in cold roll forming of UHSS

Experimental and Numerical Investigation of AA5052-H32 Al Alloy with U-Profile in Cold Roll Forming

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