Effect of ageing on phase evolution and mechanical properties of a high tungsten super-duplex stainless steel

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Abstract

The effect of ageing temperature and holding time on the precipitation of secondary phases and the mechanical properties of a 25Cr-6.7Ni-0.32N-3.0Mo-2.5 W super duplex stainless steel is examined. The ageing temperature was varied from 600 to 900 °C and the holding time was varied from 1 to 240 minutes. Two types of Cr and Mo enriched intermetallic phases, sigma (s) and chi (¿), were found to precipitate preferentially at the ferrite/austenite interface and within the ferrite grain. The precipitation of the ¿-phase occurred preferentially before the s-phase. The concentration of these secondary phases, which was quantified by a combination of microscopy and image analysis, increases with increasing ageing temperature and holding time, leading to significant reduction in the uniform strain and enhancement of the modulus, hardness and yield and tensile strengths. The measured concentration of the precipitated sigma phase is in agreement with the prediction by the Johnson-Mehl-Avrami kinetic model.
Original languageEnglish
Pages (from-to)281-289
Number of pages9
JournalMaterials Science and Engineering A
Volume535
Early online date27 Dec 2011
DOIs
Publication statusPublished - 15 Feb 2012

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Tungsten
Stainless Steel
stainless steels
tungsten
Stainless steel
Aging of materials
mechanical properties
Mechanical properties
Ferrite
ferrites
yield strength
austenite
image analysis
Austenite
Temperature
tensile strength
Image analysis
Intermetallics
temperature
intermetallics

Keywords

  • electron microscopy
  • mechanical characterisation
  • hardness measurement
  • stainlless steel
  • intermetallics
  • isothermal ageing
  • phase transformation
  • precipitation
  • hardness
  • failure
  • strength

Cite this

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title = "Effect of ageing on phase evolution and mechanical properties of a high tungsten super-duplex stainless steel",
abstract = "The effect of ageing temperature and holding time on the precipitation of secondary phases and the mechanical properties of a 25Cr-6.7Ni-0.32N-3.0Mo-2.5 W super duplex stainless steel is examined. The ageing temperature was varied from 600 to 900 °C and the holding time was varied from 1 to 240 minutes. Two types of Cr and Mo enriched intermetallic phases, sigma (s) and chi (¿), were found to precipitate preferentially at the ferrite/austenite interface and within the ferrite grain. The precipitation of the ¿-phase occurred preferentially before the s-phase. The concentration of these secondary phases, which was quantified by a combination of microscopy and image analysis, increases with increasing ageing temperature and holding time, leading to significant reduction in the uniform strain and enhancement of the modulus, hardness and yield and tensile strengths. The measured concentration of the precipitated sigma phase is in agreement with the prediction by the Johnson-Mehl-Avrami kinetic model.",
keywords = "electron microscopy, mechanical characterisation, hardness measurement , stainlless steel, intermetallics, isothermal ageing, phase transformation, precipitation, hardness, failure, strength",
author = "Akisanya, {Alfred R} and Udoka Obi and Renton, {Neill C}",
year = "2012",
month = "2",
day = "15",
doi = "10.1016/j.msea.2011.12.087",
language = "English",
volume = "535",
pages = "281--289",
journal = "Materials Science and Engineering A",
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publisher = "Elsevier BV",

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TY - JOUR

T1 - Effect of ageing on phase evolution and mechanical properties of a high tungsten super-duplex stainless steel

AU - Akisanya, Alfred R

AU - Obi, Udoka

AU - Renton, Neill C

PY - 2012/2/15

Y1 - 2012/2/15

N2 - The effect of ageing temperature and holding time on the precipitation of secondary phases and the mechanical properties of a 25Cr-6.7Ni-0.32N-3.0Mo-2.5 W super duplex stainless steel is examined. The ageing temperature was varied from 600 to 900 °C and the holding time was varied from 1 to 240 minutes. Two types of Cr and Mo enriched intermetallic phases, sigma (s) and chi (¿), were found to precipitate preferentially at the ferrite/austenite interface and within the ferrite grain. The precipitation of the ¿-phase occurred preferentially before the s-phase. The concentration of these secondary phases, which was quantified by a combination of microscopy and image analysis, increases with increasing ageing temperature and holding time, leading to significant reduction in the uniform strain and enhancement of the modulus, hardness and yield and tensile strengths. The measured concentration of the precipitated sigma phase is in agreement with the prediction by the Johnson-Mehl-Avrami kinetic model.

AB - The effect of ageing temperature and holding time on the precipitation of secondary phases and the mechanical properties of a 25Cr-6.7Ni-0.32N-3.0Mo-2.5 W super duplex stainless steel is examined. The ageing temperature was varied from 600 to 900 °C and the holding time was varied from 1 to 240 minutes. Two types of Cr and Mo enriched intermetallic phases, sigma (s) and chi (¿), were found to precipitate preferentially at the ferrite/austenite interface and within the ferrite grain. The precipitation of the ¿-phase occurred preferentially before the s-phase. The concentration of these secondary phases, which was quantified by a combination of microscopy and image analysis, increases with increasing ageing temperature and holding time, leading to significant reduction in the uniform strain and enhancement of the modulus, hardness and yield and tensile strengths. The measured concentration of the precipitated sigma phase is in agreement with the prediction by the Johnson-Mehl-Avrami kinetic model.

KW - electron microscopy

KW - mechanical characterisation

KW - hardness measurement

KW - stainlless steel

KW - intermetallics

KW - isothermal ageing

KW - phase transformation

KW - precipitation

KW - hardness

KW - failure

KW - strength

U2 - 10.1016/j.msea.2011.12.087

DO - 10.1016/j.msea.2011.12.087

M3 - Article

VL - 535

SP - 281

EP - 289

JO - Materials Science and Engineering A

JF - Materials Science and Engineering A

SN - 0921-5093

ER -