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.

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.

Hydrogen embrittlement susceptibility and permeability of two ultra-high strength steels

2006 ◽  
Vol 48 (8) ◽  
pp. 1926-1938 ◽  
Author(s):  
L.W. Tsay ◽  
M.Y. Chi ◽  
Y.F. Wu ◽  
J.K. Wu ◽  
D.-Y. Lin
Keyword(s):  
Hydrogen Embrittlement ◽  
High Strength Steels ◽  
High Strength ◽  
Ultra High Strength Steels

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.

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