Determination of Material and Process Characteristics for Hot Stamping Processes of Quenchenable Ultra High Strength Steels with Respect to a FE-based Process Design

2008 ◽  
Vol 1 (1) ◽  
pp. 411-426 ◽  
Author(s):  
M. Merklein ◽  
J. Lechler
Keyword(s):  
Process Design ◽  
Hot Stamping ◽  
High Strength Steels ◽  
High Strength ◽  
Process Characteristics ◽  
Ultra High Strength Steels

Influences of Austenitization Parameters on Properties of Martensitic Stainless Steel in Hot Stamping

2014 ◽  
Vol 1063 ◽  
pp. 194-197
Author(s):  
Kai Wang ◽  
Zhi Bin Wang ◽  
Pei Xing Liu ◽  
Yi Sheng Zhang
Keyword(s):  
Stainless Steel ◽  
Martensitic Stainless Steel ◽  
Hot Stamping ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Compression Tests ◽  
Austenitization Temperature ◽  
Bare Steel ◽  
Ultra High Strength Steels

Due to high temperature and inevitable contact with air, strong oxidation and decarburization of the bare steel exist in hot stamping of ultra-high strength steels. Martensitic stainless steel could be a potential solution with its corrosion resistance and high strength. In this paper, the influences of austenitization temperature (850 to 1000 °C) and time (3 to 10 min) on final properties of 410 martensitic stainless steel were investigated, to obtain an ultra-high strength up to 1500MPa. The hot stamping of 410 steel is simulated by compression tests with a flat die. Mechanical properties of blanks after hot stamping process were detected by tensile tests. Results show that the final strength of 410 steel increases and the plasticity decreases, with the increase of austenitization temperature and time. After austenitization at 1000 °C for 5-10 min, an ultimate tensile strength up to 1500MPa is obtained with a martensite dominated microstructure.

Mechanical Behaviour of Ceramic Beads Used as Medium for Hydroforming at Elevated Temperatures

2009 ◽  
Vol 410-411 ◽  
pp. 61-68 ◽  
Author(s):  
Marion Merklein ◽  
Martin Grüner
Keyword(s):  
Granular Material ◽  
Elevated Temperatures ◽  
Exhaust System ◽  
High Strength Steels ◽  
High Strength ◽  
Compression Direction ◽  
High Efficient ◽  
Hydroforming Process ◽  
Ultra High Strength Steels

The need of light weight construction for high efficient vehicles leads to the use of new materials like aluminium and magnesium alloys or high strength and ultra high strength steels. At elevated temperatures the formability of steel increases as the flow stresses decrease. Forming high complex geometries like chassis components or components of the exhaust system of vehicles can be done by hydroforming. The hydroforming process by oils is limited to temperatures of approximately 300 °C and brings disadvantages of possible leakage and fouling. Using granular material like small ceramic beads as medium could be an approach for hydroforming of ultra high strength steels like MS W1200 and CP W800 at temperatures up to 600 °C. The material properties of granular material are in some points similar to solid bodies, in other points similar to liquids. For understanding and simulation of the behaviour of the medium a basic characterisation of ceramic beads with different ball diameters is necessary. Powder mechanics and soil engineering give ideas for experimental setups. For the conversion of these approaches on the one hand the behaviour of the ceramic beads itself has to be characterized, on the other hand the contact between a blank and the beads have to be investigated. For the tests three different kinds of spheres with a diameter between 63 microns and 850 microns are used. In unidirectional compression test compressibility, pressure distribution in compression direction and transversal compression direction and the effect of bead fracture are investigated. The tests are carried out at different compression velocities and for multiple compressions. For determination of friction coefficients between blank and beads and determination of shear stress in bulk under compression a modified Jenike-Shear-Cell for use in universal testing machines with the possibility of hydraulic compression of the beads is built up. The gained data can be used for material modelling in ABAQUS using Mohr-Coulomb or Drucker-Prager model.

Influence of Temperature and Deformation on Phase Transformation and Vickers Hardness in Tailored Tempering Process: Numerical and Experimental Verifications

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
B. T. Tang ◽  
Q. L. Wang ◽  
S. Bruschi ◽  
A. Ghiotti ◽  
P. F. Bariani
Keyword(s):  
Vickers Hardness ◽  
Hot Stamping ◽  
High Strength Steels ◽  
High Strength ◽  
Fe Model ◽  
Forming Technology ◽  
Water Recirculation ◽  
Die Temperature ◽  
Ultra High Strength Steels ◽  
Good Agreement

Hot stamping of quenchenable ultra high strength steels currently represents a promising forming technology for the manufacturing of safety and crash relevant parts. For some applications, such as B-pillars which may undergo impact loading, it may be desirable to create regions of the part with softer and more ductile microstructure. In the article, a laboratory-scale hot stamped U-channel was produced with segmented die, which was heated by cartridge heaters and cooled by chilled water recirculation independently. It can be concluded that in order to satisfy tailored mechanical properties by introducing regions, which have an increased elongation for improved energy absorption, the minimum die temperature should be no less than 450 °C. Optical micrographs were used to verify the microstructure of the as-quenched phases with respect to the heated die temperatures. For the cooled die region, the microstructure was predominantly martensite for all the die temperatures interested. With the increase of heated die temperature, there was a decrease of Vickers hardness in the heated region due to the increasing volume fractions of bainite. The finite element (FE) model was developed to capture the overall hardness trends that were observed in the experiments. The trends between the simulations and experiments were very similar, with acceptable differences in the magnitude of Vickers hardness. The transition widths were measured and simulated and there was a quite good agreement between experiment and simulation with almost the same value of 10 mm by taking heat conduction into account.

scholarly journals Investigation of Mechanical Tests for Hydrogen Embrittlement in Automotive PHS Steels

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 934 ◽  
Author(s):  
Renzo Valentini ◽  
Michele Maria Tedesco ◽  
Serena Corsinovi ◽  
Linda Bacchi ◽  
Michele Villa
Keyword(s):  
Hydrogen Embrittlement ◽  
Hot Stamping ◽  
High Strength Steels ◽  
High Strength ◽  
Hydrogen Uptake ◽  
Mechanical Tests ◽  
Automotive Components ◽  
Four Point Bending ◽  
Innovative Materials ◽  
Ultra High Strength Steels

The problem of hydrogen embrittlement in ultra-high-strength steels is well known. In this study, slow strain rate, four-point bending, and permeation tests were performed with the aim of characterizing innovative materials with an ultimate tensile strength higher than 1000 MPa. Hydrogen uptake, in the case of automotive components, can take place in many phases of the manufacturing process: during hot stamping, due to the presence of moisture in the furnace atmosphere, high-temperature dissociation giving rise to atomic hydrogen, or also during electrochemical treatments such as cataphoresis. Moreover, possible corrosive phenomena could be a source of hydrogen during an automobile’s life. This series of tests was performed here in order to characterize two press-hardened steels (PHS)—USIBOR 1500® and USIBOR 2000®—to establish a correlation between ultimate mechanical properties and critical hydrogen concentration.

Texture analysis and joint performance of laser-welded similar and dissimilar dual-phase and complex-phase ultra-high-strength steels

2021 ◽  
Vol 174 ◽  
pp. 111035
Author(s):  
Ajit Kumar Pramanick ◽  
Hrishikesh Das ◽  
Ji-Woo Lee ◽  
Yeyoung Jung ◽  
Hoon-Hwe Cho ◽  
...  
Keyword(s):  
Texture Analysis ◽  
High Strength Steels ◽  
High Strength ◽  
Dual Phase ◽  
Complex Phase ◽  
Joint Performance ◽  
Ultra High Strength Steels
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