Effect of Microstructural Characteristics on Mechanical Properties of Ferritic Stainless Steel

Mitsuhiro Okayasu, Tomoki Shigeoka

Research output: Contribution to journalArticle

Abstract

To improve the mechanical properties of hot-rolled ferritic stainless steel (SUS430), the microstructural characteristics of SUS430 were changed using a heating process under various conditions. The hardness of SUS430 decreased upon the increase in the heating temperature to 900 °C, and the hardness increased when the sample was heated to temperatures greater than 900 °C. The high hardness of the sample heated at 1000 °C (H1000 °C) is attributed to the heating time: A high hardness was obtained for a H1000 °C sample that was heated for 1 h (H1000 °C-1h), but this decreased when the heating time was increased to more than 1 h. The high hardness of H1000 °C-1h is caused by the fine Cr23C6 precipitates that are distributed in the sample around the grain boundaries. On the other hand, the large precipitates of Cr23C6 in H1000 °C-12h decrease the hardness. The hardness value of SUS430 is directly attributed to the mechanical properties and the ultimate tensile strength. The tensile strength of H1000 °C-1h was found to be about 200% and 20% higher than the as-received and H1000 °C-12h samples, respectively. Despite the increase in the tensile strength of the H1000 °C-1h sample, the ductility was not found to decrease significantly, for example, the fracture strain was approximately 25%. This occurrence is affected by a severe slip in the ferrite base grain, and the high strength of H1000 °C-1h is influenced by the interruption of the slip by the Cr23C6 precipitates. Unlike the tensile strength, similar fatigue properties were observed for both H1000 °C-1h and H1000 °C-12h, which is associated with the low crack driving force of H1000 °C-12h, caused by the roughness-induced crack closure arising from the large Cr23C6 precipitates.

Original languageEnglish
JournalJournal of Materials Engineering and Performance
DOIs
Publication statusAccepted/In press - Jan 1 2019

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Stainless Steel
Ferritic steel
Stainless steel
Hardness
Mechanical properties
Precipitates
Tensile strength
Heating
Crack closure
Industrial heating
Ferrite
Ductility
Grain boundaries
Surface roughness
Fatigue of materials
Cracks
Temperature

Keywords

  • ferrite
  • heating
  • mechanical property
  • precipitation
  • stainless steel

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

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title = "Effect of Microstructural Characteristics on Mechanical Properties of Ferritic Stainless Steel",
abstract = "To improve the mechanical properties of hot-rolled ferritic stainless steel (SUS430), the microstructural characteristics of SUS430 were changed using a heating process under various conditions. The hardness of SUS430 decreased upon the increase in the heating temperature to 900 °C, and the hardness increased when the sample was heated to temperatures greater than 900 °C. The high hardness of the sample heated at 1000 °C (H1000 °C) is attributed to the heating time: A high hardness was obtained for a H1000 °C sample that was heated for 1 h (H1000 °C-1h), but this decreased when the heating time was increased to more than 1 h. The high hardness of H1000 °C-1h is caused by the fine Cr23C6 precipitates that are distributed in the sample around the grain boundaries. On the other hand, the large precipitates of Cr23C6 in H1000 °C-12h decrease the hardness. The hardness value of SUS430 is directly attributed to the mechanical properties and the ultimate tensile strength. The tensile strength of H1000 °C-1h was found to be about 200{\%} and 20{\%} higher than the as-received and H1000 °C-12h samples, respectively. Despite the increase in the tensile strength of the H1000 °C-1h sample, the ductility was not found to decrease significantly, for example, the fracture strain was approximately 25{\%}. This occurrence is affected by a severe slip in the ferrite base grain, and the high strength of H1000 °C-1h is influenced by the interruption of the slip by the Cr23C6 precipitates. Unlike the tensile strength, similar fatigue properties were observed for both H1000 °C-1h and H1000 °C-12h, which is associated with the low crack driving force of H1000 °C-12h, caused by the roughness-induced crack closure arising from the large Cr23C6 precipitates.",
keywords = "ferrite, heating, mechanical property, precipitation, stainless steel",
author = "Mitsuhiro Okayasu and Tomoki Shigeoka",
year = "2019",
month = "1",
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doi = "10.1007/s11665-019-04426-z",
language = "English",
journal = "Journal of Materials Engineering and Performance",
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T1 - Effect of Microstructural Characteristics on Mechanical Properties of Ferritic Stainless Steel

AU - Okayasu, Mitsuhiro

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N2 - To improve the mechanical properties of hot-rolled ferritic stainless steel (SUS430), the microstructural characteristics of SUS430 were changed using a heating process under various conditions. The hardness of SUS430 decreased upon the increase in the heating temperature to 900 °C, and the hardness increased when the sample was heated to temperatures greater than 900 °C. The high hardness of the sample heated at 1000 °C (H1000 °C) is attributed to the heating time: A high hardness was obtained for a H1000 °C sample that was heated for 1 h (H1000 °C-1h), but this decreased when the heating time was increased to more than 1 h. The high hardness of H1000 °C-1h is caused by the fine Cr23C6 precipitates that are distributed in the sample around the grain boundaries. On the other hand, the large precipitates of Cr23C6 in H1000 °C-12h decrease the hardness. The hardness value of SUS430 is directly attributed to the mechanical properties and the ultimate tensile strength. The tensile strength of H1000 °C-1h was found to be about 200% and 20% higher than the as-received and H1000 °C-12h samples, respectively. Despite the increase in the tensile strength of the H1000 °C-1h sample, the ductility was not found to decrease significantly, for example, the fracture strain was approximately 25%. This occurrence is affected by a severe slip in the ferrite base grain, and the high strength of H1000 °C-1h is influenced by the interruption of the slip by the Cr23C6 precipitates. Unlike the tensile strength, similar fatigue properties were observed for both H1000 °C-1h and H1000 °C-12h, which is associated with the low crack driving force of H1000 °C-12h, caused by the roughness-induced crack closure arising from the large Cr23C6 precipitates.

AB - To improve the mechanical properties of hot-rolled ferritic stainless steel (SUS430), the microstructural characteristics of SUS430 were changed using a heating process under various conditions. The hardness of SUS430 decreased upon the increase in the heating temperature to 900 °C, and the hardness increased when the sample was heated to temperatures greater than 900 °C. The high hardness of the sample heated at 1000 °C (H1000 °C) is attributed to the heating time: A high hardness was obtained for a H1000 °C sample that was heated for 1 h (H1000 °C-1h), but this decreased when the heating time was increased to more than 1 h. The high hardness of H1000 °C-1h is caused by the fine Cr23C6 precipitates that are distributed in the sample around the grain boundaries. On the other hand, the large precipitates of Cr23C6 in H1000 °C-12h decrease the hardness. The hardness value of SUS430 is directly attributed to the mechanical properties and the ultimate tensile strength. The tensile strength of H1000 °C-1h was found to be about 200% and 20% higher than the as-received and H1000 °C-12h samples, respectively. Despite the increase in the tensile strength of the H1000 °C-1h sample, the ductility was not found to decrease significantly, for example, the fracture strain was approximately 25%. This occurrence is affected by a severe slip in the ferrite base grain, and the high strength of H1000 °C-1h is influenced by the interruption of the slip by the Cr23C6 precipitates. Unlike the tensile strength, similar fatigue properties were observed for both H1000 °C-1h and H1000 °C-12h, which is associated with the low crack driving force of H1000 °C-12h, caused by the roughness-induced crack closure arising from the large Cr23C6 precipitates.

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