TRATAMENTO TÉRMICO E DE NITRETAÇÃO SOB PLASMA DO AÇO INOXIDÁVEL MARTENSÍTICO AISI 420

• Published in: Tecnologia em metalurgia, materiais e mineração Vol. 8; no. 2; p. 86
• Main Authors: Pinedo, Carlos Eduardo, Monteiro, Waldemar Alfredo
• Format: Journal Article
• Language: Portuguese
• Published: Sao Paulo Associação Brasileira de Metalurgia, Materiais e Mineração 01.04.2011
• Subjects: Alloys; Core hardenability; Corrosion resistance; Corrosive wear; Diamond pyramid hardness; Heat treatment; Ion nitriding; Martensitic stainless steels; Microstructure; Optical microscopy; Order parameters; Plasma; Plasmas (physics); Quenching; Quenching and tempering; Surface hardening; Surface hardness; Wear resistance; X-ray diffraction
• ISSN: 2176-1515; 2176-1523
• DOI: 10.4322/tmm.2011.014

Nitriding has been used for martensitic stainless steels to increase surface hardness. However, problems may arise related to surface hardness, core hardness, and corrosion wear resistance. This work presents results on the relation between heat treatment and plasma nitriding parameters in order to obtain the best properties combination. Heat treatments were carried out to reach hardness between 38 and 50 HRC. Plasma nitriding were carried out on temperatures ranging from 480 to 560°C, using times from 1 to 16 hours. X-ray diffraction, optical microscopy, Rockwell C hardness and Vickers microhardness techniques were used to characterize the treatments. Results show that plasma nitriding increases surface hardness up to 1,500 HV. When substrate is quenched and tempered to 50 HRC the plasma nitriding temperature has a strong influence on hardening behaviour. Increasing nitriding temperature from 480 to 560°C substrate hardness drops from 50 to 38 HRC. Otherwise, using start tempered and quenched core hardness close to 38 HRC full surface hardening is reached after plasma nitriding and no core hardness drop is verified. As a consequence different routes for heat treatment and plasma nitriding are discussed herein.