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 Feasibility study of a novel hot stamping process for Ti6Al4V alloy

2018 ◽  
Vol 190 ◽  
pp. 08001
Author(s):  
Mateusz Kopec ◽  
Kehuan Wang ◽  
Yaoqi Wang ◽  
Liliang Wang ◽  
Jianguo Lin
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
Phase Transformation ◽  
New Technology ◽  
Hot Stamping ◽  
Constant Strain Rate ◽  
Tensile Tests ◽  
Ti6al4v Titanium Alloy ◽  
Stamping Process ◽  
Forming Tools

To investigate the feasibility of a novel hot stamping process for the Ti6Al4V titanium alloy using low temperature forming tools, mechanical properties of the material were studied using hot tensile tests at a temperature range of 600 - 900°C with a constant strain rate of 1s-1. Hot stamping tests were carried out to verify the feasibility of this technology and identify the forming window for the material. Results show that when the deformation temperature was lower than 700°C, the amount of elongation was less than 20%, and it also had little change with the temperature. However, when the temperature was higher than 700°C, a good ductility of the material can be achieved. During the forming tests, parts failed at lower temperatures (600°C) due to the limited formability and also failed at higher temperatures (950°C) due to the phase transformation. The post-form hardness firstly decreased with the temperature increasing due to recovery and then increased due to the phase transformation. Qualified parts were formed successfully between temperatures of 750 - 850°C, which indicates that this new technology has a great potential in forming titanium alloys sheet components.

scholarly journals Measurement and Analysis of Heterogeneous Strain Fields in Uniaxial Tensile Tests for Boron Steel Under Hot Stamping Conditions

2020 ◽  
Vol 60 (9) ◽  
pp. 1289-1300
Author(s):  
R. Zhang ◽  
Z. Shao ◽  
J. Lin ◽  
T. A. Dean
Keyword(s):  
Temperature Gradient ◽  
Hot Stamping ◽  
Tensile Tests ◽  
Gauge Length ◽  
Image Correlation ◽  
Effect Of Temperature ◽  
Uniaxial Tensile ◽  
Boron Steel ◽  
Strain Fields ◽  
Dog Bone

Abstract Background A significant amount of uniaxial tensile tests has been carried out using Gleeble systems to investigate the viscoplastic deformation of boron steel (22MnB5) under hot stamping conditions. However, due to heat loss through the end clamps, a temperature gradient in the reduced parallel section of dog-bone shaped specimens is inevitable. Objective In the work reported in this paper, the effect of temperature gradient on measured outcomes is examined. Methods Uniaxial tensile tests on 1.5 mm thick boron steel specimens are carried out, under hot stamping conditions and strain fields are quantified using the digital image correlation (DIC) technique. The effect of gauge length on the properties of boron steel, as calculated from observed test results, is determined. Results Compared with the test at room temperature, a bell-shaped strain distribution occurs within the gauge length even before the appearance of the maximum load. Also, average strain within the gauge length, especially in the later stages, changes with gauge length within the investigated range, and thus, different engineering stress-strain curves and fracture strains are determined. In addition, normalized strain rate is significantly dependent on gauge length, which results in over 16% difference among the computed flow stresses by using a unified constitutive model. Conclusions The characterized properties of the material are dependent on gauge length and thus, a testing standard for measuring thermal-mechanical data of materials by using a Gleeble need to be defined.

Research on one-step quenching and partitioning treatment and its application in hot stamping process

2015 ◽  
Vol 231 (11) ◽  
pp. 1972-1982 ◽  
Author(s):  
Xianhong Han ◽  
Yaoyao Zhong ◽  
Pensen Xin ◽  
Zhenshan Cui ◽  
Jun Chen
Keyword(s):  
Hot Stamping ◽  
Heating System ◽  
Active Role ◽  
Mechanical Tests ◽  
Crash Test ◽  
Boron Steel ◽  
Air Cooling ◽  
Element Analysis ◽  
Quenching And Partitioning ◽  
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.

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 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.

Transformation in Austenitic Stainless Steel Sheet under Different Loading Directions

2011 ◽  
Vol 473 ◽  
pp. 444-451
Author(s):  
A.H. van den Boogaard ◽  
J. Krauer ◽  
Pavel Hora
Keyword(s):  
Phase Transformation ◽  
Martensitic Transformation ◽  
Sheet Material ◽  
Stress Triaxiality ◽  
Austenitic Stainless Steels ◽  
Tensile Tests ◽  
Sheet Forming ◽  
Uniaxial Tensile ◽  
Reference Curve ◽  
Strain Relation

The stress-strain relation for austenitic stainless steels is based on 2 main contributions: work hardening and a phase transformation from austenite to martensite. The transformation is highly temperature dependent. In most models for phase transformation from austenite to martensite, the stress triaxiality plays an important role also. The sensitivity to triaxiality is often investigated based on uniaxial compression and tensile tests. To validate the common formulation for triaxiality dependence of the martensitic transformation, a series of experiments is performed with the Twente biaxial tester for sheet material. A number of deformation directions are prescribed between plane strain and simple shear. Uniaxial tensile tests were performed at different temperatures to get a temperature corrected reference curve for the martensite–strain relation. The current results for typical stress states in sheet forming do not show the dependency on the triaxiality that is given in literature. This means that for sheet forming simulations, changes in stress state affects the martensitic transformation less than expected from tension–compression experiments.

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

2017 ◽  
Vol 207 ◽  
pp. 675-680
Author(s):  
Bingtao Tang ◽  
Chenchen Li ◽  
Guangchun Xiao ◽  
Wei Zhao ◽  
Huiping Li
Keyword(s):  
Numerical Modeling ◽  
Experimental Verification ◽  
Hot Stamping ◽  
Ductile Damage ◽  
Boron Steel ◽  
Stamping Process

Functional Gradation in Precipitation Hardenable AA7075 Alloy by Differential Cooling Strategies

2021 ◽  
Vol 883 ◽  
pp. 159-166
Author(s):  
Emad Scharifi ◽  
Moritz Roscher ◽  
Steffen Lotz ◽  
Ursula Weidig ◽  
Eric Jägle ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Particle ◽  
Hot Stamping ◽  
Aging Treatment ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Material Strength ◽  
Second Phase ◽  
Contrast Imaging ◽  
Forming Tools

Inspired by steel forming strategies, this study focuses on the effect of differential cooling on mechanical properties and precipitation kinetics during hot stamping of high strength AA7075 alloy. For this aim, different forming strategies were performed using segmented and differentially heated forming tools to provide locally tailored microstructures. Upon processing, uniaxial tensile tests and hardness measurements were used to characterize the mechanical properties after the aging treatment. Microstructure investigations were conducted to examine the strengthening mechanisms using the electron channeling contrast imaging (ECCI) technique in a scanning electron microscope (SEM). Based on the obtained results, it can be deduced that the tool temperatures play a key role in influencing the mechanical properties. Lower tool temperatures result in higher material strength and higher tool temperatures in lower mechanical properties. By changing the cooling rate with the use of differently heated forming tools, the mechanical properties can be controlled. Microstructure investigations revealed the formation of very fine and homogeneously distributed particles at cooled zones, which were associated with elevated mechanical properties due to the suppression of second phase particle formation during cooling. In contrast, coarse particles were observed at lower cooling rates, explaining the lower material strength found in these zones.

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