Forming Response of Ultra High Strength Steel Sheet to Stamping Speed during Hot Forming

2010 ◽  
Vol 160-162 ◽  
pp. 123-129 ◽  
Author(s):  
Hai Yan Yu ◽  
Li Bao ◽  
You Zhi Deng ◽  
Wei Cao
Keyword(s):  
Temperature Field ◽  
Steel Sheet ◽  
Coupling Effect ◽  
High Strength ◽  
Hot Forming ◽  
Boron Steel ◽  
Cold Forming ◽  
22Mnb5 Steel ◽  
Ultra High Strength Steel ◽  
Shaped Part

Stamping speed is an important parameter in sheet metal forming especially in hot forming. In this study, hot forming of a U-shaped part made of ultra high strength boron steel (22MnB5) sheet is simulated with solid elements. The mechanical properties of 22MnB5 steel sheet and the key process parameters are introduced in detail. Emphasis is laid on the forming response of the boron steel sheet to stamping speeds of 3.25m/s, 0.325m/s and 0.0325m/s. The mechanism of stamping speed acting on hot formability and temperature field of the stamped part is analyzed. It is demonstrated that stamping speed affects both formability and the heat transferred from blank to tools and to environment during hot forming. And the coupling effect of material properties, the heat produced during plastic deformation and heat boundary condition decides the formability and temperature field. An appropriate stamping speed is more important for hot forming than that for common cold forming.

Influences of Variable Friction Coefficient on the Hot Formability of Ultra High Strength Steel Sheet

2010 ◽  
Vol 154-155 ◽  
pp. 1450-1455
Author(s):  
Hai Yan Yu ◽  
Li Bao ◽  
You Zhi Deng ◽  
Wei Cao
Keyword(s):  
Friction Coefficient ◽  
High Strength Steel ◽  
Steel Sheet ◽  
Coupling Effect ◽  
High Strength ◽  
Hot Forming ◽  
Forming Simulation ◽  
Ultra High Strength Steel ◽  
Variable Friction ◽  
The One

Friction coefficient is an important parameter in sheet metal forming especially in hot forming. Friction condition not only influences material flow but also affects the thermal conductivity between blank and tools. In this study, varied friction coefficient is introduced to the hot forming simulation of B-pillar made of ultra high strength steel sheet 22MnB5. Three curves of friction coefficient vs. temperature are investigated. All of the heat transferred by conductivity, radiation and convection are considered in the simulation. And the temperature-dependent material and process parameters are supplied. It is demonstrated that the coupling effect among the strength and hardness of the metals, the properties of the oxide film covering blank surface and viscosity of the lubrication oil leads to the fact that the friction coefficient changes with temperature instead of constant during hot forming. The friction coefficient curve characterized by increasing first then decreasing gives the best simulation results and then is followed by the one which is characterized by decreasing first then increasing. The constant friction coefficient is the last.

Hot Forming Analysis of Car Door Bar for Ultra High Strength Steel

2010 ◽  
Vol 160-162 ◽  
pp. 836-841
Author(s):  
Yun Kai Gao ◽  
Da Wei Gao ◽  
You Zhi Deng ◽  
Wei Cao
Keyword(s):  
High Strength Steel ◽  
Thickness Distribution ◽  
High Strength ◽  
Simulation Method ◽  
Hot Forming ◽  
Forming Limit ◽  
Boron Steel ◽  
Shell Elements ◽  
Forming Simulation ◽  
Ultra High Strength Steel

Ultra high strength steel plays an important role of light weighting in automotive industry. The hot forming simulation of car door bar is processed with 22MnB5 ultra high strength boron steel. FEM is built with the 12 nodes shell elements and MAT 106 is selected in LS-DYNA. The hot forming processes include two heat transfers. One is the process from the oven to the tools after the blank is heated. The other is the process after the blank contacts the tools. The hot forming simulation results are obtained by LS-DYNA. The results show that the thickness distribution, the forming limit and the maximum effective plastic strain and other performances attain to standards. It is proved that the hot forming simulation method is correct.

Numerical and Experimental Investigation into Hot Forming of Ultra High Strength Steel Sheet

2010 ◽  
Vol 20 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Hongsheng Liu ◽  
Wei Liu ◽  
Jun Bao ◽  
Zhongwen Xing ◽  
Baoyu Song ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
High Strength Steel ◽  
Steel Sheet ◽  
High Strength ◽  
Hot Forming ◽  
Ultra High Strength Steel

Study on Hot Forming Process and Spring-Back of Ultra -High Strength Steel Based on ABAQUS

2012 ◽  
Vol 482-484 ◽  
pp. 2430-2437 ◽  
Author(s):  
De Sen Yang ◽  
Wen Liu ◽  
Guang Jun Hu ◽  
Jie Zhou ◽  
Zhu Su
Keyword(s):  
High Strength Steel ◽  
Simulation Analysis ◽  
Hot Stamping ◽  
High Strength ◽  
Hot Forming ◽  
Combination Method ◽  
Spring Back ◽  
Forming Process ◽  
Ultra High Strength Steel ◽  
Shaped Part

To research the key factor that affect on material characteristic of hot stamping, this paper studied the spring-back problem of hot forming of the ultra-high strength steel, "U" shaped part by using the combination method of numerical simulation and experimental verification. By obtaining the data of BR1500 HS isothermal tensile test, it established a "U" shaped part of thermal-mechanical coupled model which is based on ABAQUS to analyze the influences of forming speed and holding time on the forming properties. Simulation analysis showed that: When the forming speed of sheet metal is faster than 35mm/s, the rebound value is small, and further increase has no significant effect on the rebound; after holding 6s, the temperature quenching would become stable. The results verify the reliability of the finite element model. Also the study has provided a theoretical basis for determining the process parameters of the type of steel hot forming.

Hot Stamping Processing Experiments of Quenchable Boron Steel

2008 ◽  
Vol 575-578 ◽  
pp. 299-304 ◽  
Author(s):  
Jun Bao ◽  
Zhong Wen Xing ◽  
Yu Ying Yang
Keyword(s):  
Heating Temperature ◽  
Hot Stamping ◽  
Cooling Water ◽  
High Strength ◽  
Processing Parameters ◽  
Boron Steel ◽  
Complicated Shape ◽  
Water Flow Velocity ◽  
Ultra High Strength Steel ◽  
Automotive Parts

The quenchable boron steel is a novel type of ultra high strength steel used for automotive parts so as to reduce the weight of the whole automobile. The hot stamping processing experiments for bending parts were studied. The influence of the hot stamping processing parameters, such as the heating temperature, the heat holding time and the cooling water flow velocity, on the mechanics properties and microstructure of the hot stamping parts is obtained. And then the optimal ranges of these parameters are determined, which provides a basis for the control of the hot stamping process applied in complicated shape parts’ production.

Hot Forming Technique and Its Equipments for Ultra High Strength Steel

2010 ◽  
Author(s):  
Ning Ma ◽  
Ping Hu
Keyword(s):  
High Strength Steel ◽  
Chemical Engineering ◽  
Cooling System ◽  
High Strength ◽  
Hot Forming ◽  
Continuous Heating ◽  
Step Method ◽  
Three Point Bending ◽  
Ultra High Strength Steel ◽  
One Step

Hot forming of ultra high strength steel is an advanced forming technique which can not only represent the best solution to increasing the strength-to-mass ratio of sheet components, but also meet the need of higher passive safety and weight reduction. Based on independently developed mass production line of hot forming, its key forming and quenching technique and relative equipments are proposed and described, including multi-step and one-step method, die manufacturing with cooling system, continuous heating furnace and integrated manufacturing system composed of the advanced interdisciplinary technology of machining, electronic control, material and chemical engineering. Then the automobile body components are produced by the developed equipments of hot forming and moreover their mechanical properties are investigated. The typical tensile curve of the quenched components shows that the yield stress of the hot forming component is over 1000MPa, and the strength limitation is over 1600MPa. The three-point bending testing of the part is implemented. These experimental results indicate the validity of the developed technique and equipments.

Hot forming with a nonuniform temperature field using die partition cooling

2019 ◽  
Vol 116 (6) ◽  
pp. 613
Author(s):  
Cai-yi Liu ◽  
Yan Peng ◽  
Ling Kong ◽  
Lu-han Hao ◽  
Ren Zhai
Keyword(s):  
Temperature Field ◽  
Material Properties ◽  
High Strength ◽  
Strengthening Mechanism ◽  
Hot Forming ◽  
Nonuniform Temperature ◽  
Forming Process ◽  
Gradient Distribution ◽  
Forming Technology ◽  
Nonuniform Temperature Field

High strength steel hot forming technology plays an important role in achieving lightweight vehicles, improving the safety of vehicles. The tensile strength of the blank formed by traditional hot forming process is as high as 1500–2000 MPa, the strength of the formed blank is high, but the elongation is usually low and comprehensive mechanical property is not high. In this article, the process control of material gradient properties hot forming technology is summarized through the analysis of strengthening mechanism of gradient distribution hot forming technology. Based on the traditional hot forming technology, a new hot forming technology based on partition cooling to achieve material property gradient distribution is proposed. By changing the cooling rate of blank in different zones is different, and the gradient distribution of material properties is finally obtained. The DEFORM is used to analyze the hot forming process of the blank under the nonuniform temperature field of the partition cooling. A set of partition cooling hot forming die was designed independently to verify the experimental results. The evolution mechanism of microstructure and its effect on material properties during hot forming under nonuniform temperature field with partition cooling were revealed.

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