On the Mechanism of Graphitization of High-Carbon Steel

Yamanaka, Naomichi; Kusaka, Kunio

doi:10.2355/tetsutohagane1955.48.8_946

Cited by 2 publications

(3 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…13) In addition, it dissolves and stabilizes the cementite. 3) Therefore, it is considered that Mo addition enhances the supply of the supersaturated carbon atoms from the ferrite, while suppresses cementite decomposition. The ejected carbon atoms from ferrite are considered to diffuse along the stress direction and accumulate on the grain boundary.…”

Section: Discussionmentioning

confidence: 99%

“…In other words, less Mo content permits earlier decomposition of cementite, results in the earlier spherical graphitization. Similarly, as Mn reduces the solubility of carbon in ferrite 13) and stabilizes the cementite, 3) the effect of Mn for the earlier elongated graphite formation in 0.3C steel than 0.5Mo steel is implied.…”

Section: Discussionmentioning

confidence: 99%

“…This results in the precipitation of the equilibrated graphite (graphitization) 2) and degrades the mechanical properties of steels 2) by reducing the volume fraction of cementite and lowering carbon solubility in ferrite. 3) In addition, sometimes, precipitated graphite facilitates the formation and propagation of cracks. 4) Therefore, when carbon steels are used at elevated temperatures, such as in power or petrochemical plants, graphitization must be avoided.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

TTP Diagrams of Graphitization of Creep Ruptured Carbon Steels and 0.5Mo Steel

et al. 2021

View full text Add to dashboard Cite

Graphitization in carbon steels should be avoided because it results in the degradation of material performance. Safety management standards state that graphitization occurs at 698 K for carbon and carbon-Mo steels, although some standards state it to be above 738 K for carbon-Mo steels. However, recently, graphitization was found at 673 K in creep ruptured 0.3C steel. Herein, we investigated the graphitization behavior of creep ruptured 0.3C, 0.2C, and 0.5Mo steels. It was confirmed that the graphitization occurred below the specified temperatures of 673 K for the 0.3C and 0.2C steels and 723 K for the 0.5Mo steel. In addition, time-temperature-precipitation diagrams for graphite were obtained for all the steels. Elongated graphite and spherical graphite were confirmed in the 0.3C and 0.5Mo steels, while only spherical graphite was confirmed in the 0.2C steel. It was suggested that the elongated and spherical graphite were formed due to different mechanisms. The formation of elongated graphite was promoted by a higher carbon content, Mo addition, and higher applied stress, whereas that of spherical graphite was suppressed by Mo addition. Further, to accurately assess the risk of graphitization, time and temperature, as well as the stress level and different formation mechanisms, of the two types of graphite must be considered.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

TTP Diagrams of Graphitization of Creep Ruptured Carbon Steels and 0.5Mo Steel

et al. 2021

View full text Add to dashboard Cite

show abstract

Prediction of Graphitization Behavior during Long-Term Creep in Carbon Steels

2023

View full text Add to dashboard Cite

Carbon steels with ferrite and pearlite microstructures suffer from graphitization by the decomposition of cementite when exposed to elevated temperatures for long periods. Graphitization degrades the mechanical properties of the steels and increases its risk of failure. Therefore, by considering the extended life span of a thermal power plant, where carbon steels are used at elevated temperatures, evaluation of graphitization risk is necessary. This study evaluates the effect of temperature, stress, time, and chemical composition for both elongated and spherical graphitization using logistic regression of previously reported graphitization conditions in long-term creep ruptured specimens and establishes a prediction formula for graphitization occurrence. In addition, the accuracy of the prediction formula was validated by investigating the graphitization behavior of other carbon steels.

show abstract

On the Mechanism of Graphitization of High-Carbon Steel

Cited by 2 publications

References 1 publication

TTP Diagrams of Graphitization of Creep Ruptured Carbon Steels and 0.5Mo Steel

TTP Diagrams of Graphitization of Creep Ruptured Carbon Steels and 0.5Mo Steel

Prediction of Graphitization Behavior during Long-Term Creep in Carbon Steels

Contact Info

Product

Resources

About