Effect of Boron on Transformation of Low-carbon Low-alloy Steels

Yamanaka, Kazuo; Ohmori, Yasuya

doi:10.2355/isijinternational1966.17.92

Cited by 24 publications

(29 citation statements)

References 1 publication

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“…[121,122,125,126] These precipitates may act as nucleation sites for ferrite or even bainite, and thereby lower the steel hardenability. [127] They precipitate both in stable as well as metastable austenite before austenite to proeutectoid ferrite reaction. [121] The austenite grain size increases with increase in the austenitization temperature, with a concomitant decrease in the total GB area.…”

Section: Boro-carbidesmentioning

confidence: 99%

“…[12,65,69,126,165] This is explained by the fact that at higher boron contents, the solubility of B is exceeded and coarse boro-carbides such as M 23 (B,C) 6 or coarse BN form along GBs which promote the ferrite nucleation. [69,126,127,166] Figure 12 gives an overview of the typically recommended boron contents to improve hardenability. The overview clearly illustrates that the majority of reviews recommend boron contents in a range between 5 and 20 wt ppm.…”

Section: Recommended Boron Additions For Optimum Hardenabilitymentioning

confidence: 99%

“…Apart from solute boron at the austenite GBs, also fine, coherent M 23 (B,C) 6 boro-carbides can reduce the free GB energy and reduce the number of nucleation sites and thereby inhibit nucleation of ferrite phase. [121,127,138,159] Digges et al [7] assumed that due to the low solubility of boron in austenite, some boron atoms may be precipitated as some compound and form a film along the austenite GBs. The orientation relationship between austenite and M 23 (B,C) 6 has been confirmed by Yamanaka and Ohmori.…”

Section: Boron-containing Precipitatesmentioning

confidence: 99%

“…The orientation relationship between austenite and M 23 (B,C) 6 has been confirmed by Yamanaka and Ohmori. [127] On the contrary, coarse boro-carbides can promote ferrite formation and thereby decrease hardenability. This is why the size of the boro-carbides needs to be controlled properly.…”

Section: Boron-containing Precipitatesmentioning

confidence: 99%

“…The effect is explained by dissolution of BN and formation of AlN. [127] Figure 13 summarizes the conditions in which boron is effective in terms of hardenability and in which boron does not affect hardenability or can even result in a decreased hardenability.…”

Section: Boron-containing Precipitatesmentioning

confidence: 99%

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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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Section: Boro-carbidesmentioning

confidence: 99%

Section: Recommended Boron Additions For Optimum Hardenabilitymentioning

confidence: 99%

Section: Boron-containing Precipitatesmentioning

confidence: 99%

Section: Boron-containing Precipitatesmentioning

confidence: 99%

Section: Boron-containing Precipitatesmentioning

confidence: 99%

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Boron in Heat‐Treatable Steels: A Review

Sharma

Ortlepp

Bleck

2019

steel research int.

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Simulation of B Segregation at Austenite Grain Boundary in Low Carbon Steel

Enomoto,

Wang

2024

steel research int.

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The diffusion and segregation of boron (B) at the austenite grain boundary have been simulated in continuously cooled low carbon steels to elucidate the role of vacancy, the influence of austenite grain size and thermodynamic interaction between solutes. First‐principles calculations were carried out to obtain the stable configuration of B‐vacancy complexes and the binding energies therein. The thermodynamic equations of a hybrid interstitial‐substitutional solid solution were utilized to evaluate the contribution of interstitial B atoms and B‐vacancy complexes to boundary enrichment. The latter contribution did not appear to be significant probably due to their small concentration and/or low mobility. The grain growth of austenite is likely to play a significant role in B enrichment at elevated temperatures. Due to the strong C‐Mo interaction, the carbon flux in the grain interior did decrease, but the interaction within the grain boundary had a much greater influence on the segregation amount. The B enrichment in an Fe‐C‐B‐Mo quaternary alloy was simulated for comparison with experiment. A sophisticated approach, e.g., segregation energies spectrum, may be necessary to reproduce adequately the B segregation behavior, which also depends sensitively on process parameters and microstructure.

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Boron distribution in a low-alloy steel

Choi

Kim

Park

et al. 1997

Metals and Materials

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Boron distribution in a low-alloy steel (15B26:0.25C-0.29Cr-0.03Ti-0.028A1-0.0016B) has been characterized employing Fission Track Etching (FTE) method. The characteristics of boron distribution with variation of cooling rate after austenitization and through case-hardened depth after carburization were analyzed. Hardenability of 15B26 steel was also evaluated through Jominy-end-quench test and the results are as follows: It was observed that, in austenitized 15B26 steel, boron was distributed uniformly over the whole area of specimen with a little segregation along the austenite grain boundaries at higher cooling rates and boron precipitates were formed in the intergranular as well as transgranular regions at lower cooling rates. Jominy equivalents (HRC 35) of 15B26 steel were fairly increased between the Jominy temperatures of 820~ and 850~ which might result from the increase of the amount of soluble boron in austenite due to the dissolution of borocarbides between 820"C and 850~ In carburized 15B26 steel, the different through thickness features of boron distribution from the carburized surface were found; coarse nodular boron precipitates up to the depth of 150/am; uniform distribution of dissolved boron between 150--650 ~m; and segregation of boron atoms along grain boundaries in the regions deeper than 650 ~tm.

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Effect of Boron on Transformation of Low-carbon Low-alloy Steels

Cited by 24 publications

References 1 publication

Boron in Heat‐Treatable Steels: A Review

Boron in Heat‐Treatable Steels: A Review

Simulation of B Segregation at Austenite Grain Boundary in Low Carbon Steel

Boron distribution in a low-alloy steel

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