The Silicon Effect in the Tempering of Martensite in Steels

Chang, Li; Smith, George Davey

doi:10.1051/jphyscol:1984966

Cited by 15 publications

(15 citation statements)

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“…A Si buildup is also visible at one side of the carbide/matrix interface ( Figure 7(d)). This is consistent with the previous report on Si buildup at the cementite/ferrite interface observed by Chang and Smith using field ion microscopy [52] and supports the theory proposed by Owen [53] on suppression of cementite formation in Si-containing steels due to the rejection of low soluble Si from cementite and its buildup in front of the moving cementite/ferrite interface. For cementite formation to take place, diffusion of Si atoms from the interface into the ferrite matrix is required.…”

Section: Atom Probe Analysissupporting

confidence: 82%

Understanding the Behavior of Advanced High-Strength Steels Using Atom Probe Tomography

Pereloma

Beladi

Zhang

et al. 2011

Metall Mater Trans A

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The key evidence for understanding the mechanical behavior of advanced high strength steels was provided by atom probe tomography (APT). Chemical overstabilization of retained austenite (RA) leading to the limited transformation-induced plasticity (TRIP) effect was deemed to be the main factor responsible for the low ductility of nanostructured bainitic steel. Appearance of the yield point on the stress-strain curve of prestrained and bake-hardened transformationinduced plasticity steel is due to the unlocking from weak carbon atmospheres of newly formed during prestraining dislocations.

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Section: Atom Probe Analysissupporting

confidence: 82%

Understanding the Behavior of Advanced High-Strength Steels Using Atom Probe Tomography

Pereloma

Beladi

Zhang

et al. 2011

Metall Mater Trans A

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“…APT revealed the formation of ε-carbide in both analysed martensitic structures; however, failed to identify ε-carbide in the bainitic structure austempered at 230 ºC in the high silicon steel studied. These results are in agreement with previous research [28,30,[59][60][61] that demonstrated that the ε-carbide is only a precursor to the precipitation of cementite in lower bainite formed at temperatures higher than 350 ºC in medium carbon low silicon steel, whereas, it has been detected at tempering temperatures lower than 500ºC in high silicon steels.…”

Section: Nano-scale Examination Of the Structuressupporting

confidence: 93%

Examining the multi-scale complexity and the crystallographic hierarchy of isothermally treated bainitic and martensitic structures

De-Castro

Rementería

Vivas

et al. 2020

Materials Characterization

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“…[64,65] Many others have reported that elevated Si content shifts the temperature range for both austenite decomposition and cementite precipitation to higher temperatures. [9,13,31,42,46,[50][51][52][66][67][68][69][70][71][72][73][74] In contrast, the maxima in CVN impact energy vs tempering temperature that marks the start of TME are at 200°C for both the SAE 4130 steel with low silicon [65] and the MCHSS with 3.2 at. pct Si of this study.…”

Section: Mö Ssbauer Spectral Resultsmentioning

confidence: 99%

Characterization of the Carbon and Retained Austenite Distributions in Martensitic Medium Carbon, High Silicon Steel

Sherman

Cross

Kim

et al. 2007

Metall Mater Trans A

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The retained austenite content and carbon distribution in martensite were determined as a function of cooling rate and temper temperature in steel that contained 1.31 at. pct C, 3.2 at. pct Si, and 3.2 at. pct noniron metallic elements. Mo¨ssbauer spectroscopy, transmission electron microscopy (TEM), transmission synchrotron X-ray diffraction (XRD), and atom probe tomography were used for the microstructural analyses. The retained austenite content was an inverse, linear function of cooling rate between 25 and 560 K/s. The elevated Si content of 3.2 at. pct did not shift the start of austenite decomposition to higher tempering temperatures relative to SAE 4130 steel. The minimum tempering temperature for complete austenite decomposition was significantly higher (>650°C) than for SAE 4130 steel (~300°C). The tempering temperatures for the precipitation of transition carbides and cementite were significantly higher (>400°C) than for carbon steels (100°C to 200°C and 200°C to 350°C), respectively. Approximately 90 pct of the carbon atoms were trapped in Cottrell atmospheres in the vicinity of the dislocation cores in dislocation tangles in the martensite matrix after cooling at 560 K/s and aging at 22°C. The 3.2 at. pct Si content increased the upper temperature limit for stable carbon clusters to above 215°C. Significant autotempering occurred during cooling at 25 K/s. The proportion of total carbon that segregated to the interlath austenite films decreased from 34 to 8 pct as the cooling rate increased from 25 to 560 K/s. Developing a model for the transfer of carbon from martensite to austenite during quenching should provide a means for calculating the retained austenite. The maximum carbon content in the austenite films was 6 to 7 at. pct, both in specimens cooled at 560 K/s and at 25 K/s. Approximately 6 to 7 at. pct carbon was sufficient to arrest the transformation of austenite to martensite. The chemical potential of carbon is the same in martensite that contains 0.5 to 1.0 at. pct carbon and in austenite that contains 6 to 7 at. pct carbon. There was no segregation of any substitutional elements.

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The Silicon Effect in the Tempering of Martensite in Steels

Cited by 15 publications

References 0 publications

Understanding the Behavior of Advanced High-Strength Steels Using Atom Probe Tomography

Understanding the Behavior of Advanced High-Strength Steels Using Atom Probe Tomography

Examining the multi-scale complexity and the crystallographic hierarchy of isothermally treated bainitic and martensitic structures

Characterization of the Carbon and Retained Austenite Distributions in Martensitic Medium Carbon, High Silicon Steel

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