The Cause of Premature Tensile Fracture of Gas-Nitrocarburized Steel

Jaeyoon Hwang, Jeongho Han, Young Kook Lee

Research output: Contribution to journalArticle

Abstract

The objective of the present study was to investigate the mechanism of premature tensile fracture of the gas-nitrocarburized steel. For this purpose, tempered martensitic steel specimens were nitrocarburized at 853 K (580 °C) for maximum 3.5 hours, and tensile-strained at room temperature. The prolongation of nitrocarburizing time caused the high strength, the short elongation, and the heavy serrations at the yield point elongation range of the tensile flow curve. The serrations were generated by vertical cracking at the specimen surface, which started at the bottom of the gauge portion, and were propagated to the top of the gauge portion with increasing tensile strain up to the yield point elongation. The vertical cracks were triggered at the porous compound layer when the local deformation occurred by the propagation of the Lüders band from the bottom to the top of the gauge portion. The cracks readily passed through the diffusion layer with an assistance of ε-carbonitride particles, which formed at the boundaries of tempered martensite during nitrocarburizing, resulting in brittle fracture at the diffusion layer and finally in premature failure of the gas-nitrocarburized specimens.

Original languageEnglish
Pages (from-to)3912-3918
Number of pages7
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume47
Issue number8
DOIs
Publication statusPublished - 2016 Aug 1

Fingerprint

Steel
Carbonitriding
elongation
Gages
Elongation
Gases
steels
yield point
causes
cracks
gases
Cracks
prolongation
Martensitic steel
Carbon nitride
Tensile strain
Brittle fracture
high strength
martensite
Martensite

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys

Cite this

@article{c7c1bb05432c4cc1bd0d6f73dfba661d,
title = "The Cause of Premature Tensile Fracture of Gas-Nitrocarburized Steel",
abstract = "The objective of the present study was to investigate the mechanism of premature tensile fracture of the gas-nitrocarburized steel. For this purpose, tempered martensitic steel specimens were nitrocarburized at 853 K (580 °C) for maximum 3.5 hours, and tensile-strained at room temperature. The prolongation of nitrocarburizing time caused the high strength, the short elongation, and the heavy serrations at the yield point elongation range of the tensile flow curve. The serrations were generated by vertical cracking at the specimen surface, which started at the bottom of the gauge portion, and were propagated to the top of the gauge portion with increasing tensile strain up to the yield point elongation. The vertical cracks were triggered at the porous compound layer when the local deformation occurred by the propagation of the L{\"u}ders band from the bottom to the top of the gauge portion. The cracks readily passed through the diffusion layer with an assistance of ε-carbonitride particles, which formed at the boundaries of tempered martensite during nitrocarburizing, resulting in brittle fracture at the diffusion layer and finally in premature failure of the gas-nitrocarburized specimens.",
author = "Jaeyoon Hwang and Jeongho Han and Lee, {Young Kook}",
year = "2016",
month = "8",
day = "1",
doi = "10.1007/s11661-016-3567-7",
language = "English",
volume = "47",
pages = "3912--3918",
journal = "Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science",
issn = "1073-5623",
publisher = "Springer Boston",
number = "8",

}

The Cause of Premature Tensile Fracture of Gas-Nitrocarburized Steel. / Hwang, Jaeyoon; Han, Jeongho; Lee, Young Kook.

In: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, Vol. 47, No. 8, 01.08.2016, p. 3912-3918.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The Cause of Premature Tensile Fracture of Gas-Nitrocarburized Steel

AU - Hwang, Jaeyoon

AU - Han, Jeongho

AU - Lee, Young Kook

PY - 2016/8/1

Y1 - 2016/8/1

N2 - The objective of the present study was to investigate the mechanism of premature tensile fracture of the gas-nitrocarburized steel. For this purpose, tempered martensitic steel specimens were nitrocarburized at 853 K (580 °C) for maximum 3.5 hours, and tensile-strained at room temperature. The prolongation of nitrocarburizing time caused the high strength, the short elongation, and the heavy serrations at the yield point elongation range of the tensile flow curve. The serrations were generated by vertical cracking at the specimen surface, which started at the bottom of the gauge portion, and were propagated to the top of the gauge portion with increasing tensile strain up to the yield point elongation. The vertical cracks were triggered at the porous compound layer when the local deformation occurred by the propagation of the Lüders band from the bottom to the top of the gauge portion. The cracks readily passed through the diffusion layer with an assistance of ε-carbonitride particles, which formed at the boundaries of tempered martensite during nitrocarburizing, resulting in brittle fracture at the diffusion layer and finally in premature failure of the gas-nitrocarburized specimens.

AB - The objective of the present study was to investigate the mechanism of premature tensile fracture of the gas-nitrocarburized steel. For this purpose, tempered martensitic steel specimens were nitrocarburized at 853 K (580 °C) for maximum 3.5 hours, and tensile-strained at room temperature. The prolongation of nitrocarburizing time caused the high strength, the short elongation, and the heavy serrations at the yield point elongation range of the tensile flow curve. The serrations were generated by vertical cracking at the specimen surface, which started at the bottom of the gauge portion, and were propagated to the top of the gauge portion with increasing tensile strain up to the yield point elongation. The vertical cracks were triggered at the porous compound layer when the local deformation occurred by the propagation of the Lüders band from the bottom to the top of the gauge portion. The cracks readily passed through the diffusion layer with an assistance of ε-carbonitride particles, which formed at the boundaries of tempered martensite during nitrocarburizing, resulting in brittle fracture at the diffusion layer and finally in premature failure of the gas-nitrocarburized specimens.

UR - http://www.scopus.com/inward/record.url?scp=84976608617&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84976608617&partnerID=8YFLogxK

U2 - 10.1007/s11661-016-3567-7

DO - 10.1007/s11661-016-3567-7

M3 - Article

AN - SCOPUS:84976608617

VL - 47

SP - 3912

EP - 3918

JO - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science

JF - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science

SN - 1073-5623

IS - 8

ER -