Investigation Of Electrochemical Corrosion Behaviour of Liquid Nitrided AISI 4140 Steel

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Thesis Type: Postgraduate

Institution Of The Thesis: Karadeniz Technical University, Mühendislik Fakültesi, Metalurji ve Malzeme Mühendisliği Bölümü, Turkey

Approval Date: 2019

Thesis Language: Turkish

Student: Doğan Can Demir

Supervisor: Ümit Alver

Open Archive Collection: AVESIS Open Access Collection

Abstract:

In this study, AISI 4140 steel was carried out a nitration process in a cyanide salt bath for 1, 2 and 3 hour. After the nitration process to increase the corrosion resistance of samples the samples were oxidized at 380-400 ᴼC for 20 minutes. After the nitration process, the morphological properties of the nitrided and unnitrided AISI 4140 steels were characterised by scanning electron microscopy (SEM). The XRD was used to analyze of stuructural properties of the nitrided surfaces. The hardness values of the nitrided and unnitrided AISI 4140 steels were determined by the microhardness tester in the laboratory. It was also found that the hardness value of nitrided materials increased between twice and three times that of nonnitrided material. Nitrided and unnitrided AISI 4140 steel specimens were tested for corrosion at 3 different pH values (2, 7, 12) and it was determined that the corrosion behavior varied depending on the pH value of the salt solution used at the end of the test. As a result of the experiments, it was determined that the nitrided materials are superier corrosion properties than unnitrided materials.