Effect of tempering temperature and inclusions on hydrogen-assisted fracture behaviors of a low alloy steel

Li, Xinfeng; Zhang, Jin; Shen, Sicong; Wang, Yanfei; Song, Xiaolong

doi:10.1016/j.msea.2016.11.064

Cited by 59 publications

(14 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A number of experiments have been done regarding the effect of tempering treatment on the HE behavior of high strength martensitic steels, and it is regarded that the HE susceptibility of this type of steels could be lowered through the increase in tempering temperature on the condition that temper embrittlement is avoided [24,33,34,35,36,37,38]. This improvement was mainly correlated with microstructural evolution, including the decrease in dislocation density, the formation and morphology variation of carbides as well as the unavoidable strength loss for traditional low-alloy martensitic steels when the tempering temperature was high [24,34,36]. As all the tested specimens exhibited an nearly identical strength level, it is thus rational to suggest that microstructural evolution rather than strength controls their HE susceptibility.…”

Section: Discussionmentioning

confidence: 99%

Effects of Hot Stamping and Tempering on Hydrogen Embrittlement of a Low-Carbon Boron-Alloyed Steel

et al. 2018

View full text Add to dashboard Cite

The effects of hot stamping (HS) and tempering on the hydrogen embrittlement (HE) behavior of a low-carbon boron-alloyed steel were studied by using slow strain rate tensile (SSRT) tests on notched sheet specimens. It was found that an additional significant hydrogen desorption peak at round 65–80 °C appeared after hydrogen-charging, the corresponding hydrogen concentration (CHr) of the HS specimen was higher than that of the directed quenched (DQ) specimen, and subsequent low-temperature tempering gave rise to a decrease of CHr. The DQ specimen exhibited a comparatively high HE susceptibility, while tempering treatment at 100 °C could notably alleviate it by a relative decrease of ~24% at no expanse of strength and ductility. The HS specimen demonstrated much lower HE susceptibility compared with the DQ specimen, and tempering at 200 °C could further alleviate its HE susceptibility. SEM analysis of fractured SSRT surfaces revealed that the DQ specimen showed a mixed transgranular-intergranular fracture, while the HS and low-temperature tempered specimens exhibited a predominant quasi-cleavage transgranular fracture. Based on the obtained results, we propose that a modified HS process coupled with low-temperature tempering treatment is a promising and feasible approach to ensure a low HE susceptibility for high-strength automobile parts made of this type of steel.

show abstract

Section: Discussionmentioning

confidence: 99%

Effects of Hot Stamping and Tempering on Hydrogen Embrittlement of a Low-Carbon Boron-Alloyed Steel

et al. 2018

View full text Add to dashboard Cite

show abstract

“…In addition to such observations of the fracture surfaces, extensive microcracking of hydrogen-charged specimens subjected to mechanical loading also has been widely reported. For example, Li et al (2017) observed microcracks that nucleated from carbide particles in a hydrogen-charged low alloy steel (Fig. 9a) while Novak et al (2010) also reported observations of microcracks in their hydrogen-charged 4340 steel.…”

Section: 5mentioning

confidence: 91%

“…Figure9: (a) Examples of (i) a fracture surface where failure initiated from an inclusion in a hydrogencharged A485 steel(Fujita and Murakami, 2012) and (ii) hydrogen induced microcracks around carbide particles in a high strength steel(Li et al, 2017). (b) Probability of the diameters 2 • of carbide particles in 4340 steel as reported by Novak et al (2010).…”

mentioning

confidence: 90%

Hydrogen induced fast-fracture

Shishvan

Csänyi

Deshpande

2020

Journal of the Mechanics and Physics of Solids

View full text Add to dashboard Cite

One of the recurring anomalies in the hydrogen induced fracture of high strength steels is the apparent disconnect between their toughness and uniaxial tensile strength in identical hydrogen environments. Here we propose, supported by detailed atomistic and continuum calculations, that unlike macroscopic toughness, hydrogen-mediated tensile failure is a result of a fastfracture mechanism. Specifically, we show that failure originates from the fast propagation of cleavage cracks that initiate from cavities that form around inclusions such as carbide particles. The failure process occurs in two stages. In stage-A, hydrides rapidly form around the roots of stressed notches on the cavity surfaces with hydrogen fed from the hydrogen gas within the cavity. These hydrides promote cleavage fracture with the cracks propagating at > 100 ms '( until the hydrogen gas in the cavity is exhausted. Predictions of this hydrogen-assisted crack growth mechanism are supported by atomistic calculations of binding energies, mobility barriers and molecular dynamics calculations of the fracture process. Typically, cracks grow by less than 1 µm via this hydrogen-assisted mechanism and thus insufficient to cause macroscopic fracture of the specimen. However, this stage is then followed by a stage-B process where these fast propagating cracks can continue to grow, now in the absence of hydrogen supply, given an appropriate level of remote tensile stress. This is surprising because the fracture energy is now that of Fe in the absence of H and cleavage fracture requires opening tractions on the order of 15 GPa to be generated. Thus, fracture is usually precluded due to plasticity around the crack-tip. Here we show via macroscopic continuum crack growth calculations in a rate dependent elastic-plastic solid with fracture modelled using a cohesive zone that cleavage is possible if the crack propagates fast enough. This is because strain-rates at the tips of fast propagating cracks are sufficiently high for the drag on the motion of dislocations resulting from phonon scattering to limit plasticity. This combined atomistic/continuum model is used to explain a host of well-established experimental observations including (but not limited to): (i) insensitivity of the strength to the concentration of trapped hydrogen; (ii) the extensive microcracking in addition to the final cleavage fracture event and (iii) the higher susceptibility of high strength steels to hydrogen embrittlement. Importantly, we also show that the stage-A hydrogen-assisted fracture process only occurs in certain crystallographic orientations with crack-tip plasticity processes, such as twinning, blunting cracks in other orientations. This inhibits the fast-fracture mechanism in a macroscopic toughness on a polycrystalline material and thus explains the apparent contradiction between the hydrogen-assisted macroscopic toughness and tensile strength of steels.

show abstract

“…Although hydrogen embrittlement (HE) behaviors of high-strength steel have been intensively investigated [5][6][7][8][9][10], no consensus about the basic HE mechanism has been reached. Among them, the role of precipitates (type, size, quantity, etc.)…”

Section: Introductionmentioning

confidence: 99%

Effect of vanadium on hydrogen embrittlement susceptibility of high-strength hot-stamped steel

Chen

Gao

Wang

et al. 2020

J. Iron Steel Res. Int.

View full text Add to dashboard Cite

Based on the chemical composition of traditional hot-stamped steel (e.g., 22MnB5 and 30MnB5), Nb and V microalloying elements are added into 30MnB5 steel to meet the requirements of ultra-high strength, excellent ductility and potent resistance to hydrogen embrittlement (HE) at the same time. The influence of hot-stamped steel on HE was studied by conducting a hydrogen permeation method and pre-charged hydrogen slow strain rate test. Meanwhile, the experimental steel microstructures and corresponding fracture surfaces are observed and analyzed to characterize HE behavior. The results show that a finer microstructure, a lower apparent diffusion coefficient of hydrogen and a smaller percentage of strength and plasticity reduction are obtained due to the addition of the vanadium element into hot-stamped steel. Compared to the V free experimental steel, the steel with 0.14 wt.% V has a large number of dispersive precipitates and more grain boundary areas, which makes hydrogen atoms dispersedly distribute.

show abstract

Effect of tempering temperature and inclusions on hydrogen-assisted fracture behaviors of a low alloy steel

Cited by 59 publications

References 40 publications

Effects of Hot Stamping and Tempering on Hydrogen Embrittlement of a Low-Carbon Boron-Alloyed Steel

Effects of Hot Stamping and Tempering on Hydrogen Embrittlement of a Low-Carbon Boron-Alloyed Steel

Hydrogen induced fast-fracture

Effect of vanadium on hydrogen embrittlement susceptibility of high-strength hot-stamped steel

Contact Info

Product

Resources

About