Microstructural, mechanical, and corrosion characterization of plasma-nitrided plastic injection mould steel

Abstract

Plasma nitriding can be used to improve wear and corrosion behaviour of moulds for plastic injection by modifying the near-surface layers of these materials. In this study, a ferritic stainless steel (X36CrMo17) was plasma nitrided at 520-540 8C for 15-18 h under various gas mixtures of N 2 +H 2 in an industrial nitriding facility. The nitrided layer microstructures, thicknesses, and strengths were studied by X-ray diffraction (XRD), conversion electron and X-ray Mfssbauer spectroscopies (CEMS and CXMS), cross-sectional scanning electron microscopy (SEM), and cross-sectional nanohardness measurements. The corrosion behaviour was investigated by a salt spray method. Combined Mfssbauer, XRD, and SEM analyses demonstrate that (Fe,Cr,Mn)-nitrides, the q-and gV -nitrides, the Fe 3 C-like carbide, and CrN are distributed in the top nitrided layers of several micron thickness. The CEMS and CXMS analyses clearly show the nearly complete decomposition of the surface and deeper layers into phase separated mixtures of pure bcc-Fe, (Fe,Cr,Mn)-nitrides, and CrN. The nitriding conditions with the gas composition N 2 /H 2 =1 produces the thickest nitrided layer (~135 Am) with enhanced corrosion protection. The nanohardness of the surface layers is found to be plateau-shaped and increased by about a factor of three in comparison to that of the substrate material. D

Laser powder bed fusion of the steels used in the plastic injection mould industry: a review of the influence of processing parameters on the final properties

“…The plastic injection moulding industry is one of the fastest-growing industries in the world since a lot of products that are used in daily life involve the use of plastics [27][28][29]. Despite having numerous advantages, namely high dimensional and geometric precision, repeatability, and adaptability to a wide range of raw materials [30,31], the costs associated with the mould and the injection machine are high [32,33].…”

A comparative investigation of the corrosion and tribocorrosion behaviour of nitrocarburized, gas nitrided, fluidized-bed nitrided, and plasma nitrided plastic mould steel

“…It has been reported that acids and chlorides formed due to the decomposition of thermoplastics by overheating can create a corrosive environment [1]. Furthermore, during the injection moulding process, liberated gases from plastic materials at elevated temperatures can cause localized corrosion on the mould material [15]. On the other hand, plastic injection moulds suffer mechanical wear due to the relative movements of the mould parts, as well as due to the abrasive actions exerted by the reinforcement materials such as hard and abrasive fibres or whiskers [15][16][17][18].…”

Improvement of Surface Properties of Low Carbon Steel by Nitriding Treatment

“…In this investigation realized by Ozturk et al [15] a ferritic stainless steel (X36CrMo17) was plasma nitrided at 52-540…”