Segregation of phosphorus and boron in austenite in Fe-10%Mn-P-B-alloys

Paju, M.; Grabke, H. J.

doi:10.1002/srin.198900961

Cited by 23 publications

(13 citation statements)

References 22 publications

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“…This value is similar to those derived from the segregation energy of boron (57-97 kJmol -1 ) using various experimental methods, such as SIMS, 31) autoradiography, 32) and the Auger-electron microscopy, 33) and is also similar to the value reported by Hondros. 20) If the molar volume of the austenite grain boundary, V m gb , is assumed to be 7.1 × 10 -6 m…”

Section: Effect Of Boron On the Grain-boundary Energy Ofsupporting

confidence: 89%

Kinetic Model of the γ to α Phase Transformation at Grain Boundaries in Boron-bearing Low-alloy Steel

2014

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The effect of boron on the nucleation and growth of ferrite at austenite grain boundaries is examined theoretically under the assumption that the junction of 4-austenite grain boundaries (i.e., the 4-grain junctions) are the dominant nucleation sites of ferrite. Boron segregates to the austenite grain boundaries and reduces the grain-boundary energy; it thereby retards ferrite nucleation at the grain boundary. The retardation is expressed as a decrease in nucleation density due to an increase in the critical activation energy for nucleation, and the calculated value of the fraction of active nucleation sites is in satisfactory agreement with the experimental results. The reduction of the austenite grain-boundary energy, which we obtained by applying the Gibbs isotherm for adsorption to the boron segregation, is of the same order of magnitude as the reduction is deduced from the results of calculations for a decrease in the nucleation density based on experimental results. The growth of ferrite was calculated using DICTRA, which yielded both the volume fraction and the grain size of transformed ferrite as functions of time; the results agreed with the experimental results. This agreement suggests that the influence of boron on the growth rate is negligible. However, the increase in the size of the diffusion cell due to the addition of boron is considered to be the main reason for the slightly larger grain size of ferrite compared with that in boron-free steel; this result is also in good agreement with experimental observations.

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Section: Effect Of Boron On the Grain-boundary Energy Ofsupporting

confidence: 89%

Kinetic Model of the γ to α Phase Transformation at Grain Boundaries in Boron-bearing Low-alloy Steel

2014

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“…This is because in the site competition with phosphorus for segregation to GB, boron succeeds. Boron thus reduces P segregation in austenite . This is also the principle by which boron cleans the (austenite) GBs in medium Mn steels; Mn desegregates from the GBs owing to boron GB segregation and thus there is no GB embrittlement .…”

Section: Effect Of Boron On Toughness and Possible Mechanismsmentioning

confidence: 99%

“…P desegregation due to boron segregation to GB is in fact linear, as shown in the study by Liu et al, also shown in Figure . The free binding energy of boron segregation in austenite was estimated using AES to be −97, and −47 kJ mol −1 for phosphorus segregation . Morral and Jandeska Jr .…”

Section: Effect Of Boron On Toughness and Possible Mechanismsmentioning

confidence: 99%

Boron in Heat‐Treatable Steels: A Review

Sharma

Ortlepp

Bleck

2019

steel research int.

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The science and technology of boron addition to heat‐treatable steels are explained. The aim is to address the following: How to add boron to steel (i.e., the manufacturing aspects of boron addition to steel)? What precautions are necessary when alloying boron to steel, in terms of composition (mainly nitrogen, aluminum, and titanium contents), processing and heat treatment (i.e., material and process robustness and reproducibility for a consistent steel quality)? Where does boron go in steel (i.e., the state of boron, interstitial or substitutional solute, precipitate or a complex with other alloying elements; as well as the location of boron, i.e., dissolved as a solute in the grain or segregated at the grain boundary)? Which characterization methods are suitable for the detection of the very small amounts of boron (<30 wt ppm) in heat‐treatable steels? What does boron do in steel (i.e., its effect on hardenability and mechanical properties, specifically impact toughness)? How does it do and what it does (i.e., the physical mechanism by which it influences the properties)? How much boron is really required to achieve the desired properties in heat‐treatable steels (i.e., recommendations for the optimum boron content)?

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“…[159] The fact that the addition of small amount of B suppresses phosphorus segregation at austenite grain boundaries suggests that B with a large free energy of segregation, presumably about 100 kJ/mol, affects segregation of phosphorus with a free energy of about 50 kJ/moi. [160,161] Therefore, the beneficial effect of adding B to the Nb-containing steel is considered in two respects: (i) enhancement of nucleation and growth of precipitates, in the precipitation temperature range, that leads to the depletion of carbonitride precipitants in the lattice, and (ü) depletion of strengthening elements, in the dissolution temperature range of precipitants, especially Nb, in the matrix owing to the non-equilibrium cosegregation of B and Nb to the grain boundary. The effect of B atoms in solute at grain boundaries can be viable in both of these scenarios.…”

Section: Effect Of Boron On Hot Ductilitymentioning

confidence: 99%