Investigation of coating surface of AISI 1040 medium carbon steel with graphite reinforced ferro ti using TIG melting method

In the TIG coating method, which is expressed as surface modification, it is based on the rapid solidification of the coating material metallurgically bonded to the base material in order to form a thin layer on the surface in desired composition and proportions. The coating technology made by the gas tungsten arc method is not a new method. However, in terms of the process, it is more advantageous than similar methods in that it is much esasier and cheaper to produce a thicker layer under the same conditions and to create a coating layer with the desired composition and proportions. In this thesis, surface coating was performed on the substrate of 1040 stainless steel substrate by using pure TiC and graphite reinforced TiC/Graphite powder TIG welding method at different ratios (1,2,3,4,5, wt%). After the coating process, the coating thicknesses and microstructure morphology of the samples were examined with an optical microscope (OM), scanning electron microscope (SEM), Energy dispersive spektrometry (EDS), X-Ray diffraction (XRD) devices and microstructure, elemental distribution and phase components. In addition, microhardness and wear devices were used to determine the mechanical properties of the coating layer and the hardness values were measured and the wear results were characterized by microstructure. From the SEM and EDS analysis results, it was observed that more uniform and homogeneous coatings were formed and dense dendritic structures were observed. It was determined from the optical microstructure and SEM results that a good metallurgical bond was formed between the coating and the substrate. As can be seen from the EDS results, it was observed that Ti, C elements decreased as one went from the coating layer to the lower layer. On the other hand, it is thought that the element C continues to increase towards the lower parts of the interface together with the coating layer, and the main reason for this is that the element C in the lower layer rises towards the surface. As a result of XRD analysis, it was determined that the dominant phase was Fe7C3, Fe3C and martensite phases along with the TiC phase in all samples, and α-Fe and δ-Fe phases were also formed at low peak values. In the coating thicknesses measured with the help of an optical microscope, the coating thickness was 2270 μm in the N2 sample with an energy input of 1144 j/mm, while it was measured as 580 μm in the N4 sample with an energy input of 899 j/mm. With the results obtained, it is thought that the energy input in the coating thickness is an important factor in the coating work with the TIG method. When the microhardness measurement results taken from the coating surfaces were evaluated, it was observed that the 5% C reinforced sample had the highest average microhardness value with 857 HV0.1. The lowest hardness value. The average microhardness value of 756 HV0.1 was obtained from the 1% C reinforced sample. When the measurement was made without reinforcement, an average microhardness value of 715 HV0.1 was obtained. As a result, it was observed that as the amount of C increased, the hardness increased accordingly. It is thought that the main source of the high values is the effect of carbide phases formed in the coating region after solidification after melting. With the addition of C, the highest microhardness was obtained from the 5% C coating sample. When the wear results were evaluated, it was determined that the friction coefficient decreased and the wear resistance increased depending on the addition of C. According to the results obtained, the lowest friction coefficient was found to be 0.2 in the N6 sample, while the lowest friction coefficient was 0.6 in the N1 sample. In the light of these results, it was determined that the microhardness values increased and the wear resistance increased as a result of coating AISI 1040 steel, which has low wear and microhardness values, with TiC/C.