Investigation of microstructure and wear properties of stellite coated structural steel with different methods


Thesis Type: Doctorate

Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2013

Student: SERKAN APAY

Consultant: BEHÇET GÜLENÇ

Abstract:

In this study, the top surface of the AISI 1015 low carbon structural steel used in the manufacturing sector was coated by the cobalt-based alloy Stellite 6 with using laser welding, plasma transfer arc (PTA) and the TIG welding method. Microphotos were obtained fort he samples coated with Stellite 6. From those microphotos, as-received samples, HAZ, the amount of penetration and coating microstructure were investigated. The aim of this work is to determine the effect of coating methods on the amount of penetration, coating thickness and mechanical properties of steel. Wear test and hardness measurment were carried out to measure the mechanical properties. Wear test was applied to the sample coated with appropriate welding parameters under load of 10N, 25N and 40N for 5000 meters. Sliding distance on 1200 mesh emery paper at room temperature. Wear resistance of the samples were determined by measuring the weight loss per 1000 meters. In addition, microhardness measurments were made from the coated surface to the inside of the materials. Measurements were made at intervals of 0,2 mm starting from the upper surface. As a result of the wear tests, the sample coated by the laser welding method the highest wear resistance, while the lowest wear resistance was obtained for the sample coated with TIG welding method. This is consistent with the results obtained by microhardness. The sample is coated with the laser welding method revealed the highest hardness values. However samples coated with TIG welding method showed the lowest hardness values. The results indicated that Co, Cr and C alloying elements in alloy increased wear resistance and microhardness of steel. In addition to applied corrosion test samples. Laser welding with coated, corrosion resistance has been the highest sample. TIG welding has been coated sample, the lowest corrosion resistance.