Effects of dynamic strain aging on environment-assisted cracking of low alloy pressure vessel and piping steels

Hannu Hänninen, Hans-Peter Seifert, Yuriy Yagodzinskyy, Ulla Ehrnsten, Oleksandr Tarasenko, Pertti Aaltonen

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

2 Citations (Scopus)

Abstract

Strain aging occurs in alloys containing solutes that segregate strongly to dislocations. In low-alloy steels (LAS) static strain aging is a process where aging takes place after pre-straining and results in return of Lüders strain. Dynamic strain aging (DSA) is a process where aging is sufficiently rapid to occur during straining and it produces inhomogeneous deformation, serrated yielding. DSA occurs at temperatures of 150-350 °C, where stress-strain curves show serrations, being most marked at 250 °C depending on strain rate. The mechanism of DSA in LAS is explained based on the interstitial (N, C, H) interactions with dislocations and their immobilization. The important role of the accumulation of vacancies, which are diffusion vehicles for the solute atoms, is also considered in case of EAC. In general, activation energy of DSA in LAS is equal to that of N/C diffusion in ferrite. The effects of DSA of LAS are evaluated based on peaks in UTS, hardness and strain hardening rate in the DSA temperature range and minimum of ductility (A, Z) and temperature of peaks decreases with decreasing strain rate. DSA causes an increase in the ductile-to-brittle transition temperature following plastic deformation in the DSA temperature range, lowering of the ductile fracture resistance (decrease of tearing modulus) at temperatures within the DSA temperature range, as well as ductile crack instabilities (crack jumps) in the DSA temperature range, decreases low-cycle fatigue resistance and the susceptibility of LAS to EAC coincides with DSA behavior, in terms of temperature and strain rate ranges. The present knowledge of DSA on above mentioned properties of LAS is reviewed and DSA susceptibility of some pressure vessel steels is demonstrated by internal friction method and slow-strain rate tensile testing.
Original languageEnglish
Title of host publication Plant Life Management
Subtitle of host publicationProgress for structural integrity
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Pages199-221
ISBN (Electronic)951-38-6281-X
ISBN (Print)951-38-6280-1
Publication statusPublished - 2003
MoE publication typeB3 Non-refereed article in conference proceedings
EventPlant Life Management: Progress for structural integrity - Espoo, Finland
Duration: 1 Jan 20021 Jan 2002

Publication series

SeriesVTT Symposium
Number227
ISSN0357-9387

Seminar

SeminarPlant Life Management
CountryFinland
CityEspoo
Period1/01/021/01/02

Fingerprint

precipitation hardening
pressure vessels
steels
high strength steels
strain rate
temperature
hardening
solutes
cracks
magnetic permeability
tearing
strain hardening
internal friction
fracture strength
ductility
immobilization

Cite this

Hänninen, H., Seifert, H-P., Yagodzinskyy, Y., Ehrnsten, U., Tarasenko, O., & Aaltonen, P. (2003). Effects of dynamic strain aging on environment-assisted cracking of low alloy pressure vessel and piping steels. In Plant Life Management: Progress for structural integrity (pp. 199-221). Espoo: VTT Technical Research Centre of Finland. VTT Symposium, No. 227
Hänninen, Hannu ; Seifert, Hans-Peter ; Yagodzinskyy, Yuriy ; Ehrnsten, Ulla ; Tarasenko, Oleksandr ; Aaltonen, Pertti. / Effects of dynamic strain aging on environment-assisted cracking of low alloy pressure vessel and piping steels. Plant Life Management: Progress for structural integrity. Espoo : VTT Technical Research Centre of Finland, 2003. pp. 199-221 (VTT Symposium; No. 227).
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abstract = "Strain aging occurs in alloys containing solutes that segregate strongly to dislocations. In low-alloy steels (LAS) static strain aging is a process where aging takes place after pre-straining and results in return of L{\"u}ders strain. Dynamic strain aging (DSA) is a process where aging is sufficiently rapid to occur during straining and it produces inhomogeneous deformation, serrated yielding. DSA occurs at temperatures of 150-350 °C, where stress-strain curves show serrations, being most marked at 250 °C depending on strain rate. The mechanism of DSA in LAS is explained based on the interstitial (N, C, H) interactions with dislocations and their immobilization. The important role of the accumulation of vacancies, which are diffusion vehicles for the solute atoms, is also considered in case of EAC. In general, activation energy of DSA in LAS is equal to that of N/C diffusion in ferrite. The effects of DSA of LAS are evaluated based on peaks in UTS, hardness and strain hardening rate in the DSA temperature range and minimum of ductility (A, Z) and temperature of peaks decreases with decreasing strain rate. DSA causes an increase in the ductile-to-brittle transition temperature following plastic deformation in the DSA temperature range, lowering of the ductile fracture resistance (decrease of tearing modulus) at temperatures within the DSA temperature range, as well as ductile crack instabilities (crack jumps) in the DSA temperature range, decreases low-cycle fatigue resistance and the susceptibility of LAS to EAC coincides with DSA behavior, in terms of temperature and strain rate ranges. The present knowledge of DSA on above mentioned properties of LAS is reviewed and DSA susceptibility of some pressure vessel steels is demonstrated by internal friction method and slow-strain rate tensile testing.",
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Hänninen, H, Seifert, H-P, Yagodzinskyy, Y, Ehrnsten, U, Tarasenko, O & Aaltonen, P 2003, Effects of dynamic strain aging on environment-assisted cracking of low alloy pressure vessel and piping steels. in Plant Life Management: Progress for structural integrity. VTT Technical Research Centre of Finland, Espoo, VTT Symposium, no. 227, pp. 199-221, Plant Life Management, Espoo, Finland, 1/01/02.

Effects of dynamic strain aging on environment-assisted cracking of low alloy pressure vessel and piping steels. / Hänninen, Hannu; Seifert, Hans-Peter; Yagodzinskyy, Yuriy; Ehrnsten, Ulla; Tarasenko, Oleksandr; Aaltonen, Pertti.

Plant Life Management: Progress for structural integrity. Espoo : VTT Technical Research Centre of Finland, 2003. p. 199-221 (VTT Symposium; No. 227).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

TY - GEN

T1 - Effects of dynamic strain aging on environment-assisted cracking of low alloy pressure vessel and piping steels

AU - Hänninen, Hannu

AU - Seifert, Hans-Peter

AU - Yagodzinskyy, Yuriy

AU - Ehrnsten, Ulla

AU - Tarasenko, Oleksandr

AU - Aaltonen, Pertti

N1 - Project code: H2SU00363

PY - 2003

Y1 - 2003

N2 - Strain aging occurs in alloys containing solutes that segregate strongly to dislocations. In low-alloy steels (LAS) static strain aging is a process where aging takes place after pre-straining and results in return of Lüders strain. Dynamic strain aging (DSA) is a process where aging is sufficiently rapid to occur during straining and it produces inhomogeneous deformation, serrated yielding. DSA occurs at temperatures of 150-350 °C, where stress-strain curves show serrations, being most marked at 250 °C depending on strain rate. The mechanism of DSA in LAS is explained based on the interstitial (N, C, H) interactions with dislocations and their immobilization. The important role of the accumulation of vacancies, which are diffusion vehicles for the solute atoms, is also considered in case of EAC. In general, activation energy of DSA in LAS is equal to that of N/C diffusion in ferrite. The effects of DSA of LAS are evaluated based on peaks in UTS, hardness and strain hardening rate in the DSA temperature range and minimum of ductility (A, Z) and temperature of peaks decreases with decreasing strain rate. DSA causes an increase in the ductile-to-brittle transition temperature following plastic deformation in the DSA temperature range, lowering of the ductile fracture resistance (decrease of tearing modulus) at temperatures within the DSA temperature range, as well as ductile crack instabilities (crack jumps) in the DSA temperature range, decreases low-cycle fatigue resistance and the susceptibility of LAS to EAC coincides with DSA behavior, in terms of temperature and strain rate ranges. The present knowledge of DSA on above mentioned properties of LAS is reviewed and DSA susceptibility of some pressure vessel steels is demonstrated by internal friction method and slow-strain rate tensile testing.

AB - Strain aging occurs in alloys containing solutes that segregate strongly to dislocations. In low-alloy steels (LAS) static strain aging is a process where aging takes place after pre-straining and results in return of Lüders strain. Dynamic strain aging (DSA) is a process where aging is sufficiently rapid to occur during straining and it produces inhomogeneous deformation, serrated yielding. DSA occurs at temperatures of 150-350 °C, where stress-strain curves show serrations, being most marked at 250 °C depending on strain rate. The mechanism of DSA in LAS is explained based on the interstitial (N, C, H) interactions with dislocations and their immobilization. The important role of the accumulation of vacancies, which are diffusion vehicles for the solute atoms, is also considered in case of EAC. In general, activation energy of DSA in LAS is equal to that of N/C diffusion in ferrite. The effects of DSA of LAS are evaluated based on peaks in UTS, hardness and strain hardening rate in the DSA temperature range and minimum of ductility (A, Z) and temperature of peaks decreases with decreasing strain rate. DSA causes an increase in the ductile-to-brittle transition temperature following plastic deformation in the DSA temperature range, lowering of the ductile fracture resistance (decrease of tearing modulus) at temperatures within the DSA temperature range, as well as ductile crack instabilities (crack jumps) in the DSA temperature range, decreases low-cycle fatigue resistance and the susceptibility of LAS to EAC coincides with DSA behavior, in terms of temperature and strain rate ranges. The present knowledge of DSA on above mentioned properties of LAS is reviewed and DSA susceptibility of some pressure vessel steels is demonstrated by internal friction method and slow-strain rate tensile testing.

M3 - Conference article in proceedings

SN - 951-38-6280-1

T3 - VTT Symposium

SP - 199

EP - 221

BT - Plant Life Management

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -

Hänninen H, Seifert H-P, Yagodzinskyy Y, Ehrnsten U, Tarasenko O, Aaltonen P. Effects of dynamic strain aging on environment-assisted cracking of low alloy pressure vessel and piping steels. In Plant Life Management: Progress for structural integrity. Espoo: VTT Technical Research Centre of Finland. 2003. p. 199-221. (VTT Symposium; No. 227).