scholarly journals Improving Hydrogen Embrittlement Resistance of Hot-Stamped 1500 MPa Steel Parts That Have Undergone a Q&P Treatment by the Design of Retained Austenite and Martensite Matrix

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1585
Author(s):  
Zhou Wang ◽  
Mingxin Huang
Keyword(s):  
Hydrogen Embrittlement ◽  
Retained Austenite ◽  
High Strength ◽  
Tensile Tests ◽  
Hydrogen Trapping ◽  
Dog Bone ◽  
Hot Stamped Steel ◽  
Martensite Matrix ◽  
Embrittlement Resistance ◽  
Hydrogen Embrittlement Resistance

Hydrogen embrittlement is one of the largest obstacles against the commercialisation of ultra-high strength quenching and partitioning (Q&P) steels with ultimate tensile strength over 1500 MPa, including the hot stamped steel parts that have undergone a Q&P treatment. In this work, the influence of partitioning temperature on hydrogen embrittlement of ultra-high strength Q&P steels is studied by pre-charged tensile tests with both dog-bone and notched samples. It is found that hydrogen embrittlement resistance is enhanced by the higher partitioning temperature. Then, the hydrogen embrittlement mechanism is analysed in terms of hydrogen, retained austenite, and martensite matrix. Thermal desorption analysis (TDA) shows that the hydrogen trapping properties are similar in the Q&P steels, which cannot explain the enhancement of hydrogen embrittlement resistance. On the contrary, it is found that the relatively low retained austenite stability after the higher temperature partitioning ensures more sufficient TRIP effect before hydrogen-induced fracture. Additionally, dislocation recovery and solute carbon depletion at the higher partitioning temperature can reduce the flow stress of the martensite matrix, improving its intrinsic toughness and reducing its hydrogen sensitivity, both of which result in the higher hydrogen embrittlement resistance.

scholarly journals Chemical heterogeneity enhances hydrogen resistance in high-strength steels

2021 ◽  
Author(s):  
Binhan Sun ◽  
Wenjun Lu ◽  
Baptiste Gault ◽  
Ran Ding ◽  
Surendra Kumar Makineni ◽  
...  
Keyword(s):  
Hydrogen Embrittlement ◽  
Thermomechanical Processing ◽  
High Strength Steels ◽  
High Strength ◽  
High Dispersion ◽  
Chemical Heterogeneity ◽  
Hydrogen Trapping ◽  
Strength And Ductility ◽  
Embrittlement Resistance ◽  
Hydrogen Embrittlement Resistance

AbstractThe antagonism between strength and resistance to hydrogen embrittlement in metallic materials is an intrinsic obstacle to the design of lightweight yet reliable structural components operated in hydrogen-containing environments. Economical and scalable microstructural solutions to this challenge must be found. Here, we introduce a counterintuitive strategy to exploit the typically undesired chemical heterogeneity within the material’s microstructure that enables local enhancement of crack resistance and local hydrogen trapping. We use this approach in a manganese-containing high-strength steel and produce a high dispersion of manganese-rich zones within the microstructure. These solute-rich buffer regions allow for local micro-tuning of the phase stability, arresting hydrogen-induced microcracks and thus interrupting the percolation of hydrogen-assisted damage. This results in a superior hydrogen embrittlement resistance (better by a factor of two) without sacrificing the material’s strength and ductility. The strategy of exploiting chemical heterogeneities, rather than avoiding them, broadens the horizon for microstructure engineering via advanced thermomechanical processing.

Effect of Cooling Rate below Ms Temperature on Hydrogen Embrittlement of TRIP-Aided Martensitic Steels

2021 ◽  
Vol 1016 ◽  
pp. 654-659
Author(s):  
Naoya Kakefuda ◽  
Shintaro Aizawa ◽  
Ryo Sakata ◽  
Junya Kobayashi ◽  
Goroh Itoh ◽  
...  
Keyword(s):  
Hydrogen Embrittlement ◽  
Cooling Rate ◽  
Trip Steel ◽  
Retained Austenite ◽  
Volume Fraction ◽  
High Strength ◽  
Martensitic Steels ◽  
The Matrix ◽  
Embrittlement Resistance ◽  
Hydrogen Embrittlement Resistance

Low alloy TRIP steel is expected to be applied to automobile bodies because of its high strength, high ductility, and excellent impact properties and press formability. It has been reported that the low alloy TRIP steel of hydrogen embrittlement resistance is improved by utilizing the hydrogen storage characteristics of highly stable retained austenite. Therefore, for the purpose of increasing the volume fraction of retained austenite, it was produced at various cooling rates below the martensite transformation start temperature. As a result, the volume fraction of retained austenite increased, and then the effect of hydrogen embrittlement decreased. The matrix phase and retained austenite is refined with decrees of the cooling rate. It is considered that the size and surface area of the retained austenite also affected the improvement of hydrogen embrittlement resistance.

Hydrogen Embrittlement Resistance of High Strength 9260 Bar Steel Heat Treated by Quenching and Partitioning

2021 ◽  
Author(s):  
E. Hoyt ◽  
E. De Moor ◽  
K.O. Findley
Keyword(s):  
Hydrogen Embrittlement ◽  
Carbon Content ◽  
Hydrogen Concentration ◽  
Retained Austenite ◽  
Volume Fraction ◽  
High Strength ◽  
Quenching And Partitioning ◽  
Quench Temperature ◽  
Embrittlement Resistance ◽  
Hydrogen Embrittlement Resistance

Abstract The influence of microstructure on hydrogen embrittlement of high strength steels for fastener applications is explored in this study. Space limiting applications in areas such as the automotive or agricultural industries provide a need for higher strength fasteners. Albeit, hydrogen embrittlement susceptibility typically increases with strength. Using a 9260 steel alloy, the influence of retained austenite volume fraction in a martensitic matrix was evaluated with microstructures generated via quenching and partitioning. X-ray diffraction and scanning electron microscopy were used to assess the influence of retained austenite in the matrix with different quenching parameters. The quench temperatures varied from 160 °C up to 220 °C, and a constant partitioning temperature of 290 °C was employed for all quench and partitioned conditions. The target hardness for all testing conditions was 52-54 HRC. Slow strain rate tensile testing was conducted with cathodic hydrogen pre-charging that introduced a hydrogen concentration of 1.0-1.5 ppm to evaluate hydrogen embrittlement susceptibility of these various microstructures. The retained austenite volume fraction and carbon content varied with the initial quench temperature. Additionally, the lowest initial quench temperature employed, which had the highest austenite carbon content, had the greatest hydrogen embrittlement resistance for a hydrogen concentration level of 1.0-1.5 ppm.

scholarly journals Effects of Alloying Elements Addition on Delayed Fracture Properties of Ultra High-Strength TRIP-Aided Martensitic Steels

Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 6 ◽  
Author(s):  
Tomohiko Hojo ◽  
Junya Kobayashi ◽  
Koh-ichi Sugimoto ◽  
Akihiko Nagasaka ◽  
Eiji Akiyama
Keyword(s):  
Hydrogen Embrittlement ◽  
Retained Austenite ◽  
Hydrogen Diffusion ◽  
High Strength ◽  
Alloying Elements ◽  
Bending Test ◽  
Hydrogen Trapping ◽  
Martensitic Steels ◽  
Diffusible Hydrogen ◽  
Martensite Matrix

To develop ultra high-strength cold stamping steels for automobile frame parts, the effects of alloying elements on hydrogen embrittlement properties of ultra high-strength low alloy transformation induced plasticity (TRIP)-aided steels with a martensite matrix (TM steels) were investigated using the four-point bending test and conventional strain rate tensile test (CSRT). Hydrogen embrittlement properties of the TM steels were improved by the alloying addition. Particularly, 1.0 mass% chromium added TM steel indicated excellent hydrogen embrittlement resistance. This effect was attributed to (1) the decrease in the diffusible hydrogen concentration at the uniform and fine prior austenite grain and packet, block, and lath boundaries; (2) the suppression of hydrogen trapping at martensite matrix/cementite interfaces owing to the suppression of precipitation of cementite at the coarse martensite lath matrix; and (3) the suppression of the hydrogen diffusion to the crack initiation sites owing to the high stability of retained austenite because of the existence of retained austenite in a large amount of the martensite–austenite constituent (M–A) phase in the TM steels containing 1.0 mass% chromium.

Effects of Microstructure on the Hydrogen Embrittlement Resistance of Ultra High Strength Martensitic Steel Sheets

2021 ◽  
Vol 1016 ◽  
pp. 1331-1336
Author(s):  
Kosuke Shibata ◽  
Takuya Hiramatsu ◽  
Atsuhiro Shiraki ◽  
Junichiro Kinugasa ◽  
Tatsuya Asai ◽  
...  
Keyword(s):  
Low Temperature ◽  
Hydrogen Embrittlement ◽  
Carbon Content ◽  
Fracture Morphology ◽  
Hydrogen Trapping ◽  
Tempered Martensite ◽  
Interstitial Carbon ◽  
Steel Sheets ◽  
Embrittlement Resistance ◽  
Hydrogen Embrittlement Resistance

In this study, the relationship between hydrogen embrittlement resistance (HER) and the microstructure of low temperature tempered martensite was investigated using steel sheets which were controlled by carbon content and tempering conditions. Focusing on transition carbides and interstitial carbon content which are peculiar microstructures to low temperature tempered martensite, microstructure was evaluated by synchrotron radiation X-ray diffraction (SR-XRD). The HER was evaluated by U-bending and fracture surface was observed after the slow strain rate test (SSRT). As the result, the HER was improved and fracture morphology was changed from intergranular to quasi-cleavage when the high carbon content and high temperature tempering were adopted. In the steels improved the HER, the increase of the volume fraction of transition carbides and the decrease of interstitial carbon content was confirmed. Hydrogen trapping by the transition carbides could explain the change of the HER and fracture morphology. These results suggested that the hydrogen trapping by the transition carbides was effective to improve the HER of the low temperature tempering martensitic steels.

scholarly journals Comparison of Hydrogen Embrittlement Resistance of High Strength Steel Sheets Evaluated by Several Methods

2016 ◽  
Vol 56 (4) ◽  
pp. 685-692 ◽  
Author(s):  
Shusaku Takagi ◽  
Yukito Hagihara ◽  
Tomohiko Hojo ◽  
Wataru Urushihara ◽  
Kaoru Kawasaki
Keyword(s):  
Hydrogen Embrittlement ◽  
High Strength Steel ◽  
High Strength ◽  
Steel Sheets ◽  
Embrittlement Resistance ◽  
Hydrogen Embrittlement Resistance
Sign in / Sign up

Export Citation Format

Share Document