In this article, the occurrence of secondary cyclic hardening (SCH) and its effect on high-temperature cyclic deformation and fatigue life of 316LN Stainless steel are presented. SCH is found to result from planar slip mode of deformation and enhance the degree of hardening over and above that resulted from dynamic strain aging. The occurrence of SCH is strongly governed by the applied strain amplitude, test temperature, and the nitrogen content in the 316LN SS. Under certain test conditions, SCH is noticed to decrease the low cycle fatigue life with the increasing nitrogen content. © The Minerals, Metals &amp; Materials Society and ASM International 2013.

S. Sankaran

Department of Metallurgical and Materials Engineering

G. V. Prasad Reddy

R. Sandhya

M. D. Mathew

316LN STAINLESS STEELS

Cyclic deformations

DEGREE OF HARDENING

DYNAMIC STRAIN AGING

LOW CYCLE FATIGUE BEHAVIOR

LOW CYCLE FATIGUE LIFE

MODE OF DEFORMATION

Test temperatures

Deformation

Hardening

nitrogen

Fatigue of materials

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Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science

In this study, the influence of cyclic strain amplitude on the evolution of cyclic stress-strain response and the associated cyclic deformation mechanisms in 316LN stainless steel with varying nitrogen content (0.07 to 0.22 wt pct) is reported in the temperature range 773 K to 873 K (500 °C to 600 °C). Two mechanisms, namely dynamic strain aging and secondary cyclic hardening, are found to strongly influence the cyclic stress response. Deformation substructures associated with both the mechanisms showed planar mode of deformation. These mechanisms are observed to be operative over certain combinations of temperature and strain amplitude. For strain amplitudes >0.6 pct, wavy or mixed mode of deformation is noticed to suppress both the mechanisms. Cyclic stress-strain curves revealed both single and dual-slope behavior depending on the test temperature. Increase in nitrogen content is found to increase the tendency toward planar mode of deformation, while increase in strain amplitude leads to transition from planar slip bands to dislocation cell/wall structure formation, irrespective of the nitrogen content in 316LN stainless steel. © 2014 The Minerals, Metals & Materials Society and ASM International.

Low cycle fatigue behavior of 316LN stainless steel alloyed with varying nitrogen content. Part I: Cyclic deformation behavior

Influence of nitrogen content on low cycle fatigue life and fracture behavior of 316LN stainless steel (SS) alloyed with 0.07 to 0.22 wt pct nitrogen is presented in this paper over a range of total strain amplitudes (±0.25 to 1.0 pct) in the temperature range from 773 K to 873 K (500 °C to 600 °C). The combined effect of nitrogen and strain amplitude on fatigue life is observed to be complex i.e., fatigue life either decreases/increases with increase in nitrogen content or saturates/peaks at 0.14 wt pct N depending on strain amplitude and temperature. Coffin-Manson plots (CMPs) revealed both single-slope and dual-slope strain-life curves depending on the test temperature and nitrogen content. 316LN SS containing 0.07 and 0.22 wt pct N showed nearly single-slope CMP at all test temperatures, while 316LN SS with 0.11 and 0.14 wt pct N exhibited marked dual-slope behavior at 773 K (500 °C) that changes to single-slope behavior at 873 K (600 °C). The changes in slope of CMP are found to be in good correlation with deformation substructural changes. © 2014 The Minerals, Metals & Materials Society and ASM International.

Low cycle fatigue behavior of 316LN stainless steel alloyed with varying nitrogen content. Part II: Fatigue life and fracture behavior

The effect of nitrogen alloying (0.078% to 0.22%) in 316 LN stainless steel has been investigated for its Low Cycle Fatigue properties in the temperature range 300 to 873 K. The effect of dynamic strain ageing has been evaluated as a function of nitrogen content, temperature, strain amplitude and strain rate. The temperature range of operation of DSA has been found to be a strong function of the above parameters. Increase in nitrogen content shifted the range of operation of DSA to higher temperatures. For temperatures ≤673 K, fatigue life is found to be maximum for a nitrogen content of 0.14 wt%, while it is found to saturate or increase with increasing nitrogen content at temperatures <673 K. © 2010 Published by Elsevier Ltd.

Fulltext

Procedia Engineering

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Low cycle fatigue behaviour in vacuum of a 316L-type austenitic stainless steel between 20 and 600°C—Part II: Dislocation structure evolution and correlation with cyclic behaviour

Influence of secondary cyclic hardening on the low cycle fatigue behavior of nitrogen alloyed 316LN Stainless steel

Journal	Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
ISSN	10735623
Open Access	No