Untitled in english

Author(s)

Sandro Diniz de Oliveira

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Escola Politécnica (EP/BC)
• Defense date: 1999-12-15

Examining board members

Andre Paulo Tschiptschin; Ivan Gilberto Sandoval Falleiros; Telmo Roberto Strohaecker

• Advisor: Andre Paulo Tschiptschin

Abstract

The NM P40 steel was designed to be used in polymer injection mould, reaching 38-42 Rockwell C hardness after aging treatment. The use of a surface hardening treatment in injection moulds is necessary because of the wearing conditions in order to increase the tool performance. In this work, the possibility of nitriding and aging the NM P40 steel at the same thermochemical cycle was studied in order to eliminate one step in manufacture of polymer injection mould. The effect of plasma nitriding termal cycle in sample hardness was analyzed in order to compare solution treated samples and aged samples after plasma nitriding treatment. The samples were nitrite at 500 and 530°C, from 2 to 10 hours. The effect of methone gas in plasma nitrited layers was studied. The presented phases at nitrited samples surfaces were also studied by X-ray diffraction methods, and the nitrited layer characteristics were determined by optical microscopy, surface roughness analysis and microhardness profile. The results showed that the plasma nitriding process was eficiente to provide a surface hardening. Solution treated samples reached core hardness after nitriding treatment, similar to aged samples, showing the possibility of nitriding and aging at the same treatment. Previous aged sample do not show loss of core hardness after nitriding. (AU)