Paper Title:
Mechanism and Kinetics of Plasma Nitriding of the Nb-Alloyed PM Tool Steel
  Abstract

The aim of this work was to describe the mechanism and kinetics of plasma nitriding of a Nb-containing PM (powder metallurgy) tool steel. Material containing 2.5 wt.% C, 3.3% Si, 6.2% Cr, 2.2% Mo, 2.6% V, 2.6% Nb and 1.0% W was prepared by nitrogen melt atomization and hot isostatic pressing. Heat-treated steel (quenching from 1100 °C, triple tempering at 550 °C for 1h) was plasma nitrided at temperatures ranging from 470 °C to 530 °C / 30 - 180 min. Light microscopy, TEM, SEM and WDS were used to study the nitrided steel. It has been shown, that nitriding at 470°C leads to the formation of thin layers composed only of a diffusion zone containing nitrogen-rich martensite and fine nitride precipitates, no layer of nitrides is formed on the surface. Nitriding is probably controlled by the nitrogen diffusion in martensite to the material or by the processes in the nitriding atmosphere at this temperature. Nitriding at the temperature of 500°C and more leads to the formation of a continuous layer of nitrides and carbonitrides on the surface that limits further nitrogen diffusion. Niobium, as a prospective element in tool steels, was not found to play a role in the formation of the nitrided layer directly. Niobium replaces vanadium in very thermodynamically stable primary MC carbides. This results in higher vanadium content in others less stable carbides and in the matrix. Due to this effect, higher portion of vanadium can precipitate as VC carbides and VN nitrides during heat treatment and nitriding, respectively.

  Info
Periodical
Edited by
J. Čermák and I. Stloukal
Pages
87-92
DOI
10.4028/www.scientific.net/DDF.263.87
Citation
P. Novák, D. Vojtěch, J. Šerák, M. Novák, B. Bártová, "Mechanism and Kinetics of Plasma Nitriding of the Nb-Alloyed PM Tool Steel", Defect and Diffusion Forum, Vol. 263, pp. 87-92, 2007
Online since
March 2007
Export
Price
$32.00
Share

In order to see related information, you need to Login.

In order to see related information, you need to Login.

Authors: In Sup Lee, Yong Ho Park, Ik Min Park
Abstract:Plasma radical nitriding has been performed to harden the surface of SKD 61 steel for 1- 10 hours at temperature range of 450-550°C. A NH...
155
Authors: Mourad Keddam, B. Bouarour, R. Kouba, Redoune Chegroune
Abstract:This work deals with a study of the nitriding potential effect on development of the compound layer during the gas nitriding of Armco Fe...
133
Authors: José Lemus-Ruiz, Ana L. Salas-Villaseñor, Osvaldo Flores
Abstract:Solid-state direct diffusion bonding between commercially pure nickel and tungsten carbide (with 6%Cobalt) has been carried out in the...
127
Authors: Yuan Gao, Cheng Lei Wang, Bing Li, Xuan Nan Chen
Abstract:Using plasma alloying technique, Q235 steel was firstly treated by W-Mo-Y Multi-elements co-diffusion followed by plasma nitriding process....
1146
Authors: Feng Tang, Jin Yong Xu, Yan Tang, Cheng Gao, Peng Gao, Bo Gao, Wei Heng Mo, Yuan Ming Li
Chapter 2: Surface Engineering/Coatings
Abstract:The Cu-Ce infiltration layer was formed on 304 Stainless Steel surface by double glow plasma surface metallurgy technology. The effects of...
298