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Flow Behaviour of Modified 9Cr–1Mo Steel at Elevated Temperatures

  • V. Shiva
  • Sunil Goyal
  • R. Sandhya
  • K. Laha
  • A. K. Bhaduri
Technical Paper
  • 81 Downloads

Abstract

In this investigation, the flow behaviour of modified 9Cr–1Mo steel at elevated temperatures is reported. To understand the flow behaviour of the steel, tensile tests were performed at nominal strain rate of 3 × 10−3 s−1 and temperatures in the range of 300–823 K. The yield strength and ultimate tensile strength were found to decrease with increase in temperature with a plateau in a intermediate temperature regime (523–673 K). Serrations were also observed in the tensile curve at intermediate temperatures which caused plateau/peak in tensile behaviour of material and was a typical manifestation of dynamic strain ageing. An attempt was made to represent the flow behaviour of the material using different constitutive equations viz., Hollomon, Ludwik, Swift, Ludwigson and Voce. It was observed that the Voce equation could describe the experimental flow curve at different temperatures quite well. Instantaneous work hardening rate with respect to flow stress exhibited two stages of hardening especially at relatively lower temperatures.

Keywords

Modified 9Cr–1Mo steel Tensile behaviour Yield strength Dynamic strain ageing Constitutive equations 

List of symbols

σ

True stress

ɛ

True strain

ɛ0

Pre strain

σ0

Pre stress

\({\text{K}}_{\text{H}} ,\,{\text{K}}_{\text{L}} ,\,{\text{K}}_{\text{S}} ,\,{\text{K}}_{1}\)

Strength coefficient of Hollomon, Ludwik, Swift and Ludwigson equations respectively

\({\text{n}}_{\text{H}} ,\,{\text{n}}_{\text{L}} ,\,{\text{n}}_{\text{S}} ,\,{\text{n}}_{1}\)

Strain hardening exponent of Hollomon, Ludwik, Swift and Ludwigson equations respectively

σS

Saturation stress

σI

Initial stress

Notes

Acknowledgements

The authors express their deep sense of gratitude to Dr. G. Amarendra, Director, Metallurgy and Materials Group, IGCAR for keen interest in this work and encouragement. The authors are thankful to Ms. S. Panneer Selvi for help during experiments. Authors would like to thank Mr. D. P. Rao Palaparti for the fruitful technical discussion.

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Copyright information

© The Indian Institute of Metals - IIM 2017

Authors and Affiliations

  1. 1.Indira Gandhi Centre for Atomic ResearchHBNIKalpakkamIndia

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