Thermal fatigue of hot working steel after hybrid surface treatment

Authors: Smolik, J; Mazurkiewicz, A

Source: International Heat Treatment & Surface Engineering, Volume 5, Number 4, December 2011 , pp. 175-179(5)

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Abstract:

The application of surface treatment methods like ion nitriding, physical vapour deposition (PVD) coatings and their combination in duplex treatments effectively reduces the occurrence of oxidation, corrosion, erosion and wear processes. However, it is still uncertain whether nitriding and duplex treatment have any real effect on the decrease in the nucleation and growth of thermal fatigue cracks on the surface. This paper presents the results of thermal fatigue investigations of a nitrided layer and different composite layers ‘nitrided layer/PVD coating’ (TiN, CrN and TiAlN) obtained on the EN X40CrMoV5·1 hot working steel. The ion nitrided only and three different duplex treated substrates were compared, based on the intensity of the thermal fatigue cracks observed after testing. The nitrided layer and composite layers investigated were obtained with the use of the hybrid surface treatment technology consisting of ion nitriding followed by arc evaporation coating deposition. Apparatus based on high frequency induction heating and water spray cooling was used for thermal fatigue tests under the following conditions: maximum temperature 600°C, minimum temperature 80°C and two different rates of thermal cycling: 500 and 1000. The thermal fatigue intensities of the nitrided layer and the three different composite layers were measured according to the surface crack density and crack length (i.e. penetration into the testpiece) after different numbers of thermal cycles. Finally, based on the results obtained, the influence of different PVD coatings in the composite layer on the increase in thermal fatigue resistance of hot working steel was discussed.

Keywords: Duplex treatment; Thermal fatigue; Arc evaporation; Plasma nitriding

Document Type: Original Article

DOI: http://dx.doi.org/10.1179/174951411X13203192322144

Affiliations: Institute for Sustainable Technologies - National Research Institute, Pułaskiego 6/10, 26-600 Radom, Poland

Publication date: 2011-12-01

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