Effect of Nitriding Current Density on the Surface Properties and Crystallite Size of Pulsed Plasma-Nitrided AISI 316L

J C Díaz-Guillén,L Álvarez-Contreras,J A Aguilar-Martínez,M R Díaz-Guillén,E E Granda-Gutiérrez,G Vargas-Gutiérrez

doi:10.4236/msce.2015.31007

Abstract

In this work, plasma-nitrided AISI 316L stainless steel samples were performed by ion nitriding process under pulsed direct current (DC) discharge at different current densities (1 to 2.5 mA/ cm 2 ). The effect of nitriding current density on the size of crystalline coherently diffracting domains (crystallite size) and strain grade was investigated using X-ray diffraction (XRD) coupled with Williamson-Hall method. Additionally, hardness and wear resistance of the nitriding layer were characterized using a Vickers indenter and pin-on-disk technique respectively. Results showed a decrease in crystallite size from 99 nm for untreated samples to 1.4 nm for samples nitrided at 2.5 mA/cm2 promoted both: an increase in hardness from 226 HV25g to 1245 HV25g, and a considerably decrease in volume loss by wear effect.

Highlights

Stainless steels are well known by good corrosion resistance; their surface hardness and wear resistance are relatively poor and insufficient for many technological applications
In this work we evaluated the effect of nitriding current density on the crystallite size and strain grade of plasma nitrided austenitic stainless steel samples and the variation of both were correlated to surface hardness and wear susceptibility
For all the nitride samples, X-ray diffraction (XRD) patterns showed that the γ-austenite peaks [γ(111) and γ(200)] were shifted to a lower 2θ angles, compared with the peaks from the untreated sample, suggesting a lattice deformation phenomenon and showing the characteristic XRD pattern of the expanded austenite [17]

Summary

Introduction

Stainless steels are well known by good corrosion resistance; their surface hardness and wear resistance are relatively poor and insufficient for many technological applications. Plasma or ion nitriding is one of the techniques used in surface engineering to increase the surface properties of these steels. This technique uses the direct current (DC) glow discharge phenomena to introduce elemental nitrogen in the surface of metallic pieces for subsequent diffusion process into the crystalline lattice of the material. In the last years, pulsed plasma nitriding of AISI 316L stainless steel has been used to increase its tribological. How to cite this paper: Díaz-Guillén, J.C., et al (2015) Effect of Nitriding Current Density on the Surface Properties and Crystallite Size of Pulsed Plasma-Nitrided AISI 316L.

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Conclusion