Nitriding and carbonitriding of 1010 and 1040 steel surface with eloctroplated hard chromium

Steels maintain the features of being the most used material for centuries because of their some superior mechanic properties. Nowadays steels are in many different forms since their chemical compounds and internal structures are different. Steels, in different features according to the usage aim, are acquired by adding alloy elements in different rates and/or by controlling the internal structure with various treatments. In spite of their superior features, there are some limitations of steels. These limitations arise from the material features of surface zone. Some kinds of steels show low corrosion resistance and this situation shorten the steels? bench life. Besides the visible negative changes in steels which are corroded, losses of features occur such as decreasing in strength and worsening tribological aspects.Steels which have low resistance against wear and corrosion are subjected to surface treatments with the aim of improving the low surface properties. Surface treatments are performed by both creating new layer on the material surface and changing the chemical compounds of the surface.Alloy elements can be occurred by deposition on the steel surface and alloying after the production, besides by adding in the steel structure. These treatments which are performed locally provide advantages such as cost saving and containing of different properties.This study consists of 7 parts. In the first part, there are introduction, the aim of the dissertation and literature. In the second part steels and improving the properties of steels are mentioned. After mentioned diffusion and its mechanisms in the third part, nitriding and nitrocarburising which are two of the diffusion methods is mentioned in the fourth and fifth parts respectively. Sixth part consists of experimental studies. Conclusions are summarized generally in the seventh part.In this study, AISI 1010 and AISI 1040 steel surfaces which electrolytically plated hard chromium and are exposed to plasma nitriding process at 3 different temperatures (600, 700 and 800 0C), with a gas mixture of %60 N2 + %40 H2 for 5 hours. Also, gas nitrocarburizing process is performed to electroplated hard chromium steels at 560 0C with a gas mixture of %45 CO2 + %29 NH3 + %26 N2 for 8 hours. Steel samples subjected to surface treatments are characterized with XRD analyses. Then microstructural analysises are completed with the scanning electron microscope and then EDS and Line Scan analysis are done. After that, experiments of adhesion and hardness are implemented and corrosion tests are carried out with %3.5 NaCl solution. With the findings, samples are compared in terms of different conditions and materials.In conclusion, in steel samples are electroplated hard chromium and exposed to nitrocarburizing experiment conditions which are selected in the process of nitrocarburizing are inappropriate. In plasma nitriding process, the best conditions are obtained in experiments done with 600 0C temperature for 5 hours considering corrosion resistance and adhesion property for both AISI 1010 and AISI 1040 steels and 800 0C temperature for 5 hours considering hardness for AISI 1010 steel.