Temper embrittlement of structural alloy steels (review)

Zabil'skii, V. V.

doi:10.1007/bf00735489

Cited by 25 publications

(12 citation statements)

References 24 publications

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“…Therefore, thirty-six different starting positions were randomly selected within a sphere of radius √3/2 ( is the lattice parameter) around each atomic site in the vicinity of the TJ (Figure 1c). 7; (3) the order of binding behavior at the Σ3-Σ3-Σ9 and Σ3-Σ11-Σ33 TJs listed from highest to lowest is Fe-He, Fe-P, Fe-V and Fe-H, respectively; (4) in the case of P which is known to cause temper embrittlement in steel [86], the TJs show a strong affinity for P to bind near the TJ core with a small fraction of binding sites away from the TJ core and (5) in the case of the substitutional V atom, only a small number of sites around the TJs were energetically favorable for the impurity atom to bind. Interestingly, along the constituent GBs, the V atom had negligible energetic preference (in agreement with previous simulations, e.g.…”

Section: Solute (H He V and P) Binding Behaviormentioning

confidence: 99%

Atomic-scale investigation of triple junction role on defects binding energetics and structural stability in α-Fe

Adlakha

Solanki

2016

Acta Materialia

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Nanocrystalline (NC) metals (mean grain sizes d ≤ 100 nm) have enhanced mechanical strength as compared to coarse-grained metals (d ≥ 1 µm), and thus, are a promising alternative as structural materials for future high energy nuclear reactors. However, during extreme conditions, the NC microstructure has been found to be thermodynamically unstable, thereby limiting its applicability. Further, for materials with average grain size < 10 nm, the triple junctions (TJs) have been observed to have a significant contribution on the mechanical behavior and microstructural stability. Moreover, at the atomic-scale, the region surrounding the TJ demonstrates unique physical properties, such as rapid diffusion, non-equilibrium segregation and increased dislocation activity. Therefore, in this work, we systematically assess the role of TJs on the structural stability and the solute binding behavior in α-Fe. Using atomistic simulations, we show that the TJ resolved line tension is strongly correlated (inversely) with the mean activation energy for self-diffusion along the TJ, i.e., the thermodynamically unstable TJs demonstrated a lower activation energy barrier for self-diffusion along TJs with higher line tension. Next, we demonstrated that the strain energy evolution around the TJ can provide insights into the distinct binding behavior of point defects and solute atoms. In other words, the examination of solute binding behavior revealed a localized region of stable sites around the TJs which aids in accommodation of high solute concentration at high temperatures. In summary, our findings quantify the distinct role of TJs on the defect (vacancy, self-interstitial and solute atom) binding and migration behavior and these findings are necessary for designing future structural materials for extreme environments, including those needed in aerospace, naval, civilian and energy sector infrastructures.

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Section: Solute (H He V and P) Binding Behaviormentioning

confidence: 99%

Atomic-scale investigation of triple junction role on defects binding energetics and structural stability in α-Fe

Adlakha

Solanki

2016

Acta Materialia

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“…This element was chosen because it is known to cause temper embrittlement in steels [69]. The site to site variation of impurity elements can be studied using binding energy calculations which provide an insight into the variation in the binding energy between an impurity atom and a GB along with structural characteristics of the GB.…”

Section: Binding Energymentioning

confidence: 99%

“…Here, we probed the variation with respect to one substitutional atom (P) and one interstitial atom (H) over the entire length scale. These elements are highly embrittling in nature [10,69] and this mapping also provides information about the symmetry and distribution of binding energies for the system. Several sites within 15 Å of the Σ13(320)θ=67.38° GB are selected for calculating these binding energies The respective plots are shown in Figure 7.…”

Section: Binding Energymentioning

confidence: 99%

Grain Boundary Segregation of Interstitial and Substitutional Impurity Atoms in Alpha-Iron

Rajagopalan

Tschopp

Solanki

2013

JOM

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The macroscopic behavior of polycrystalline materials is influenced by the local variation of properties caused by the presence of impurities and defects. The effect of these impurities at the atomic scale can either embrittle or strengthen grain boundaries within. Thus, it is imperative to understand the energetics associated with segregation to design materials with desirable properties. Here, molecular statics simulations were employed to analyze the energetics associated with the segregation of various elements (helium, hydrogen, carbon, phosphorous, and vanadium) to four <100> (5 and 13 GBs) and six <110> (3,9,and11 GBs) symmetric tilt grain boundaries in alpha-Fe. This knowledge is important for designing stable interfaces in harsh environments. Simulation results show that the local atomic arrangements within the GB region and the resulting structural units have a significant influence on the magnitude of binding energies of the impurity (interstitial and substitutional) atoms. This data also suggests that the site-to-site variation of energies within a boundary is substantial. Comparing the binding energies of all ten boundaries shows that the 3(112) boundary possesses a much smaller binding energy for all interstitial and substitutional impurity atoms among the boundaries examined here. Additionally, based on the Rice-Wang model, our total energy calculations show that V has a significant beneficial effect on the Fe grain boundary cohesion, while P has a detrimental effect on grain boundary cohesion, much weaker than H and He. This is significant for applications where extreme environmental damage generates lattice defects and grain boundaries act as sinks for both interstitial and substitutional impurity atoms. This methodology provides us with a tool to effectively identify the local as well as the global segregation behavior which can influence the GB cohesion.

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“…The phenomenon of temper embrittlement in steel has been observed firstly around the year 1885 to occur on heavy forgings. Since this time, because of appearance of spectacular failure events in engineering designs, has been item of very extensive investigations, described in detail in literature [2][3][4][5][6]. For weld materials, less investigations published [7].…”

Section: Reversible Temper Embrittlement (Rte) Treatmentmentioning

confidence: 99%

Atom probe investigations on temper embrittlement and reversible temper embrittlement in S 690 steel weld metal

Cerjak

Martín

Domakova

2017

Science and Technology of Welding and Joining

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Severe embrittlement was observed in weld material of a brand new penstock of a huge hydro power plant. Temper embrittlement (TE) was found as root case of embrittlement. Reversible temper embrittlement (RTE) treatment characterised by a short-time heating at about 600°C, by which the toughness of embrittled weld material can significantly be recovered, was qualified and successfully applied in the plant. Basic investigations were performed to explain the embrittlement as well as the de-embrittlement effect. By the application of high resolution analytics as Atom Probe Tomography (APT) applied on TE as well as on the RTE-treated material, revealed phosphorus segregation in the grain boundaries as root cause of embrittlement. By application of RTE treatment the APT results revealed, that the phosphorus segregation in the grain boundaries disappeared. The mechanism of this behaviour can be explained by referring the McLean [Grain boundaries in metals. Oxford: Clarendon Press; 1957] based grain boundary equilibrium segregation of phosphorous. During RTE treatment, which occur at higher temperatures (600°C) that segregation (which starts during cooling at about 550°C), desegregation occurs. During this higher temperature, the diffusion is much faster than segregation producing the fast recovery of toughness.

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Temper embrittlement of structural alloy steels (review)

Cited by 25 publications

References 24 publications

Atomic-scale investigation of triple junction role on defects binding energetics and structural stability in α-Fe

Atomic-scale investigation of triple junction role on defects binding energetics and structural stability in α-Fe

Grain Boundary Segregation of Interstitial and Substitutional Impurity Atoms in Alpha-Iron

Atom probe investigations on temper embrittlement and reversible temper embrittlement in S 690 steel weld metal

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