Analysis of Relaxation Processes in HNS Due to Interstitial-Substitutional Pairs

Alessandra Fava,Roberto Montanari,Alessandra Varone,Maria Richetta

doi:10.3390/met7070246

Abstract

Mechanical Spectroscopy (MS) tests have been performed on a high nitrogen (0.8 wt %) austenitic steel (HNS) with resonance frequencies in the range of kHz. Two sets of samples have been examined: the first set in an as-prepared condition, the second one submitted to a heat treatment of 2 h at 800 °C, which induces a discontinuous precipitation of Cr2N phase. In both sets, the damping spectrum shows a broad peak whose position and shape is changed by the precipitation of Cr2N phase. The results are explained by considering interstitial-substitutional (i-s) interactions.

Highlights

In austenitic steels, nitrogen induces solid solution strengthening, increases corrosion resistance, and stabilizes the γ phase [1,2,3,4,5]
The aim of the present paper is to describe the anelastic effects arising from different interstitial systems present in a High Nitrogen Steels (HNS) in an as-prepared condition and after annealing for 2 h at 800 ◦ C, which is a treatment inducing the discontinuous precipitation of chromium nitrides
The image analysis has been performed on 20 micrographs (500 ×) through the software LUCIA (Version 4.51, Za Drahou, Praha, Czech Republic, 1991–2000): the grain size is ~50 μm, and some twins are observed

Summary

Introduction

Nitrogen induces solid solution strengthening, increases corrosion resistance, and stabilizes the γ phase [1,2,3,4,5]. Background strongly depends on grain size and on grain size and dislocation density, since heat treatment substantially does not change ondislocation grain size and dislocation density, since thethe heat treatment substantially not change density, since the heat treatment substantially does not changedoes these factors [14], these factors [14], the background level is stable These factors the background level is stable. The peak shift to higher temperature with respect to the as-received steel depends on the. The peak shift to to a higher temperature with respect to to thethe as-received steel depends onon thethe. The peak shift aa higher temperature with respect as-received steel depends presence of the transformed austenite, the re-orientation of.

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Results

Conclusion