Prediction of Microstructure and Mechanical Properties in Hot Stamping

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.

scholarly journals Study on Phase Transformation in Hot Stamping Process of USIBOR® 1500 High-Strength Steel

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1119 ◽  
Author(s):  
Pengyun Zhang ◽  
Le Zhu ◽  
Chenyang Xi ◽  
Junting Luo
Keyword(s):  
Phase Transformation ◽  
High Strength Steel ◽  
Hot Stamping ◽  
High Strength ◽  
Transformation Kinetics ◽  
Martensite Content ◽  
Cct Curve ◽  
Stamping Process ◽  
Quenching Process ◽  
Kinetics Of

Based on the Kirkaldy-Venugopalan model, a theoretical model for the phase transformation of USIBOR® 1500 high strength steel was established, and a graph of the phase transformation kinetics of ferrite, pearlite, and bainite were plotted using the software MATLAB. Meanwhile, with the use of the software DYNAFORM, the thermal stamping process of an automobile collision avoidance beam was simulated. The phase transformation law of USIBOR® 1500 high-strength steel during hot stamping was studied through a simulation of the phase transformation during the pressure holding quenching process. In combination with the continuous cooling transformation (CCT) curve, the cooling rate of quenching must be greater than 27 °C/s to ensure maximum martensite content in the final parts, and the final martensite content increases as the initial temperature of the sheet rises.

scholarly journals Thermomechanical-Phase Transformation Simulation of High-Strength Steel in Hot Stamping

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Wenhua Wu ◽  
Ping Hu ◽  
Guozhe Shen
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Phase Transformation ◽  
High Strength Steel ◽  
Hot Stamping ◽  
Constitutive Models ◽  
High Strength ◽  
Simulation Software ◽  
Transmission Model ◽  
Stamping Process

The thermomechanical-phase transformation coupled relationship of high-strength steel has important significance in forming the mechanism and numerical simulation of hot stamping. In this study a new numerical simulation module of hot stamping is proposed, which considers thermomechanical-transformation multifield coupled nonlinear and large deformation analysis. In terms of the general shell finite element and 3D tetrahedral finite element analysis methods related to temperature, a coupled heat transmission model for contact interfaces between blank and tools is proposed. Meanwhile, during the hot stamping process, the phase transformation latent heat is introduced into the analysis of temperature field. Next the thermomechanical-transformation coupled constitutive models of the hot stamping are considered. Static explicit finite element formulae are adopted and implemented to perform the full numerical simulations of the hot stamping process. The hot stamping process of typical U-shaped and B-pillar steel is simulated using the KMAS software, and a strong agreement comparison between temperature, equivalent stress, and fraction of martensite simulation and experimental results indicates the validity and efficiency of the hot stamping multifield coupled constitutive models and numerical simulation software KMAS. The temperature simulated results also provide the basic guide for the optimization designs of cooling channels in tools.

scholarly journals Effect of the Die Temperature and Blank Thickness on the Formability of a Laser-Welded Blank of a Boron Steel Sheet with Removing Al-Si Coating Layer

2014 ◽  
Vol 6 ◽  
pp. 925493 ◽  
Author(s):  
M. S. Lee ◽  
J. H. Moon ◽  
C. G. Kang
Keyword(s):  
Automobile Industry ◽  
Steel Sheet ◽  
Coating Layer ◽  
Hot Stamping ◽  
Thin Sheet ◽  
Welding Process ◽  
High Strength ◽  
Absorption Capacity ◽  
Boron Steel ◽  
Thick Sheet

Reducing carbon emissions has been a major focus in the automobile industry to address various environmental issues. In particular, studies on parts comprised of high strength sheets and light car bodies are ongoing. Accordingly, this study examined the use of boron steel, which is commonly used in high strength sheets. Boron steel is a type of sheet used for hot stamping parts. Although it has high strength, the elongation is inferior, which reduces its crash energy absorption capacity. To solve this problem, two sheets of different thickness were welded so the thin sheet would absorb crash energy and the thick sheet would work as a support. Boron steel, however, may show weakening at the welding spot due to the Al-Si coating layer used to prevent oxidation from occurring during the welding process. Therefore, a certain part of the coating layer of a double-thickness boron steel sheet that is welded in the hot stamping process is removed through laser ablation, and the formability of the hot-work was examined.

A Study on Laser Weldability of Al-Si Coated Boron Steel According to Hot-Stamping Heat Treatment

2015 ◽  
Vol 1110 ◽  
pp. 113-117
Author(s):  
Jong Do Kim ◽  
So Young Choi ◽  
Moo Keun Song
Keyword(s):  
Heat Treatment ◽  
Coating Layer ◽  
Hot Stamping ◽  
Fuel Efficiency ◽  
High Strength ◽  
Boron Steel ◽  
Dimensional Precision ◽  
Before And After ◽  
Hot Stamped Steel ◽  
High Level

Numerous studies recently have been conducted to reduce the weight of finished products and increase their fuel efficiency by using hot-stamping processes in the transport industry. Hot-stamping is a method where boron steel is formed and cooled in a press die directly after it is heated to a temperature of 900 °C or higher to obtain a material with a high-strength of 1,500 MPa or more. It is advantageous in that a high level of quality can be ensured because the spring-back phenomenon, a problem associated with high-strength steel materials, can be overcome while the degree of dimensional precision is improved by 90 % or more due to the good formability compared with existing types of steel. In this study, specimens were welded with a laser before and after the hot-stamping process of boron steel, welding characteristics according to heat treatment were elucidated, and mechanical properties were compared. Also, the effect of laser welding on flow from the Al-Si coating layer into the weld was investigated through an analysis of microstructure. The obtained results indicated that, in the case of the boron steel, hardness increased rapidly at the weld. For the hot-stamped steel, there was a sharp reduction of the hardness by tempering in the HAZ. It was found that the Al-Si coating layer flowed into the weld and was segregated when welding was carried out. This resulted in reduced hardness of the weld.

scholarly journals Steel sheets partnered with quenchable sheet in hot stamping of tailor-welded blanks and its application to separation prevention of fractured components

2020 ◽  
Vol 111 (3-4) ◽  
pp. 725-734
Author(s):  
Ken-ichiro Mori ◽  
Yasutaka Suzuki ◽  
Daisuke Yokoo ◽  
Michiya Nishikata ◽  
Yohei Abe
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
Mild Steel ◽  
Hot Stamping ◽  
High Strength ◽  
Boron Steel ◽  
Air Cooling ◽  
High Ductility ◽  
Steel Sheets ◽  
Tailor Welded Blanks

Abstract The phase transformation and mechanical properties of non-quenchable steels partnered with the quenchable boron steel in hot stamping of tailor-welded blanks were evaluated to produce tailored components with partially balanced strength and ductility. The effect of the forming start temperature after natural air cooling on the phase transformation and mechanical properties for 270 MPa mild steel, non-quenchable steel, 440 MPa high strength steel, and 22MnB5 steel sheets was examined, and the 270 MPa and non-quenchable sheets had enough ductility after hot stamping. Tailored components having a hardness of about 500 HV1 in the high strength zone and a total elongation of about 30% in the high ductility zone were hot-stamped from a tailor-welded blank composed of 22MnB5 and 270 MPa sheets. It was found that the 270 MPa mild steel sheet is sufficient as a partner sheet of tailor-welded blanks. In addition, the safety of hot-stamped components was heightened by welding a 22MnB5 main blank with a 270 MPa steel patch. Even if the main blank is fractured by a collision, the hot-stamped component is not separated by the 270 MPa patch having high ductility.

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

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.

scholarly journals Constitutive modeling of TA15 alloy sheet coupling phase transformation in non-isothermal hot stamping process

2021 ◽  
Vol 12 ◽  
pp. 629-642
Author(s):  
Yuan Chen ◽  
Shuhui Li ◽  
Yongfeng Li ◽  
Yaoqi Wang ◽  
Zhiqiang Li ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Constitutive Modeling ◽  
Hot Stamping ◽  
Alloy Sheet ◽  
Coupling Phase ◽  
Stamping Process ◽  
Ta15 Alloy
Sign in / Sign up

Export Citation Format

Share Document