The microstructure and wear properties of pulse plasma treated AISI 4140 steel was investigated. The surface properties of the materials have been improved by modifying the surfaces of the DIN 1.2210 steel with pulse plasma technique. The sample surfaces have been modified by pulse plasma with C3H8, nitrogen and O2 gases. Two different distances between the sample and nozzle and three different numbers of pulse were determined for modification process and the surface process was implemented by using tungsten electrode with 800 µF battery capacity. The optical images were taken of the materials which the surfaces were improved by using pulse plasma technique. The surface modified samples were subjected to X-ray diffraction analysis. Wear tests were performed in a linear wear test machine with 0.15 m/s constant sliding speed under 5 N loads for 200 m sliding distance. The wear rate was changed in accordance with process parameters. The wear resistance increased in the surface modified specimens was compared to that of non-modified ones. Worn surfaces of specimens were studied by scanning electron microscope and energy dispersive spectroscopy analyses techniques. It is determined that the thickness of modification layer changes regarding to the amount of new phases and sample-nozzle distance. It is approved the increase on wear resistance related to wolfram diffusion.

This method can be used for the surface modification treatment of materials producing different surface properties. This paper presents the results obtained from an experimental work investigating the changes in some mechanical and microstructural surface properties of a 1.3343 steel (M2 high speed steel). In this work, a battery capacity of 800 µF, and four different sample plasma gun nozzle distances were used. The consumable electrode is tungsten in this work. The samples were subjected to micro-hardness measurements and it was found that the hardness values of modified surfaces are five-seven times higher than that of untreated samples. The modified surface layers were examined using an optical microscope and X-ray analyses were carried out for all samples. It was observed that surface treatment had led to the formation of new phases in surface layers. SEM and EDS analyses were applied to modified surface.

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