Effects of austenitization temperature on the microstructure of 15BCr30 and PL22 boron steels

Suski, Cássio Aurélio; Oliveira, Carlos A. S.

doi:10.1590/s1516-14392013005000054

Cited by 6 publications

(5 citation statements)

References 11 publications

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“…The austenite grain size increases with increase in the austenitization temperature, with a concomitant decrease in the total GB area. Thus, the boron content per unit GB area increases, which in turn facilitates the precipitation of Fe 23 (B,C) 6 at the austenite grain boundary (AGB) …”

Section: Thermodynamicsmentioning

confidence: 99%

“…Thus, the boron content per unit GB area increases, which in turn facilitates the precipitation of Fe 23 (B,C) 6 at the austenite grain boundary (AGB). [128] Thermo-Calc calculations on different boron-containing steels ( Table 3) show that the substitutional elements in M 23 (B,C) 6 are mainly Fe and Cr, whereby the Cr content of M 23 (B,C) 6 is directly proportional to the Cr content of the respective steel ( Figure 7). Boro-cementite also contains some Cr (apart from Fe and some Mn), which also increases with increasing Cr content.…”

Section: Boro-carbidesmentioning

confidence: 99%

See 1 more Smart Citation

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: Thermodynamicsmentioning

confidence: 99%

Section: Boro-carbidesmentioning

confidence: 99%

Boron in Heat‐Treatable Steels: A Review

Sharma

Ortlepp

Bleck

2019

steel research int.

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“…The decrease in V f from 1000 o C to 1150 o C was found to be 90% and 75% in C 23 and C 55 respectively. Compared to the AR condition, there is an increase in the fraction of precipitates due to 1150 o C austenitizing treatment for C 21 and C 23 , while this fraction is lower for C 55 . This suggests that precipitation of carbides continues even at 1150 o C in C 21 and C 23 , while it is starting to dissolve in C 55 .…”

Section: Effect Of Hardening Temperature and Ln 2 Treatment On Matrixmentioning

confidence: 87%

Austenite stability and M2C carbide decomposition in experimental secondary hardening ultra-high strength steels during high temperature austenitizing treatments

Veerababu

Prasad

Phani

et al. 2018

Materials Characterization

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The present study deals with the austenite stability and M 2 C carbide decomposition in three secondary hardening ultra-high strength (SHUHS) steels with varying levels of Cr and Mo (2Cr-1Mo, 2Cr-3Mo and 5Cr-5Mo) investigated using Vicker's hardness, optical and electron microscopy. These steels were subjected to high temperature austenitizing treatments at 1000, 1050, 1100 and 1150 o C. It has been established that increasing both Cr and Mo to 5wt. % as well as increasing the austenitizing temperature in this class of SHUHS steels is stabilizing the austenite such that almost 100% austenite is produced upon oil quenching. Further, higher Cr and Mo is also found to influence the stability of metastable M 2 C carbide formed during processing of the steels. While the M 2 C carbide in 2Cr-3Mo steel remained untransformed, it was found to transform partially to M 6 C during austenitization of 5Cr-5Mo steel. Hardness measurements on these steels revealed that hardness is relatively insensitive to austenitizing temperature in 2Cr-1Mo steel, decreased in 2Cr-3Mo and decreased more drastically in 5Cr-5Mo steel with austenitizing temperature. This dependence has been correlated to the influence of composition on M s temperature and hence on retention of austenite as well as primary carbides. The experimental results were compared against theoretical calculations using ThermoCalc, which predict the presence of only M 6 C in both 2Cr-3Mo and 5Cr-5Mo steels. The apparent discrepancy between theoretical and experimental observations has been correlated to kinetic factors.

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“…This small change in Ac 1 temperature, although within the experimental deviation of the technique, is consistent with the differences in chemical composition presented in Table 1. Comparing position 2 with position 1, it was observed an increase in the contents of C, Mn and B, which may contribute to the decrease of the critical temperatures [28][29][30] , as well as the Si content which has a strong effect on the increase of these temperatures [31][32][33] . However, a more pronounced effect of the elements C, Mn and B than the effect of Si is observed, resulting in a decrease in the Ac 1 temperature.…”

Section: Dilatometrymentioning

confidence: 99%

Effect of the Chemical Homogeneity of a Quenched and Tempered C-Mn Steel Pipe on the Mechanical Properties and Phase Transformations

et al. 2019

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Seamless steel pipes for application in the oil and gas industries are manufactured from quenched and tempered steel. Aiming to meet the required characteristics, it is necessary that the microstructure and the mechanical properties are homogeneous along the wall thickness of the pipes, which is even more critical for thick wall pipes. Considering the seamless steel pipe manufacturing process, any chemical segregation along the thickness could affect the phase transformation kinetics during heat treatments and, consequently, microstructure and mechanical properties. In this context, this pioneer work when evaluating the effect of the chemical homogeneity of a seamless pipe on the mechanical properties and phase transformations. The studied pipe was manufactured by a C-Mn steel designed for oil and gas industry applications. Two regions of the pipe wall were analyzed-a region close to the inner surface and another near the outer surface. The steel was subjected to quenching and tempering heat treatments. Scanning electron and optical microscopy techniques were used to characterize the resultant microstructures. Microhardness and Charpy impact tests were performed aiming to analyze the pipe mechanical behavior in the studied regions. In addition, dilatometric tests were performed in order to determine the continuous cooling transformation diagrams of these regions.

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Effects of austenitization temperature on the microstructure of 15BCr30 and PL22 boron steels

Cited by 6 publications

References 11 publications

Boron in Heat‐Treatable Steels: A Review

Boron in Heat‐Treatable Steels: A Review

Austenite stability and M2C carbide decomposition in experimental secondary hardening ultra-high strength steels during high temperature austenitizing treatments

Effect of the Chemical Homogeneity of a Quenched and Tempered C-Mn Steel Pipe on the Mechanical Properties and Phase Transformations

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