The Influence of Cyclic and Isothermal Hot Corrosion on Nickel Based Superalloy

Abstract

Nickel-based superalloys have a wide range of usage area such as gas turbines, nuclear reactors, generators. They are especially preferred in areas where mechanical strength and corrosion resistance are important. Hot corrosion is a highly corrosive type of damage in high temperature applications. In hot corrosion, molten salts easily react with reactive components, causing premature damage to the workpieces. In this study, Inconel 718 was subjected to hot corrosion tests as a nickel-based superalloy. 50% V2O5-50% Na2SO4 mixtures were used as corrosion salt. Cyclic and isothermal hot corrosion tests were carried out at 900 ° C for 18 hours. Corrosion products and microstructural changes formed in Inconel 718 were characterized by scanning electron microscopy (SEM), SEM-Energy Dispersive X-Ray (EDX), SEM-mapping and X-Ray Diffraction (XRD) analysis after hot corrosion tests. At the end of the isothermal and cyclic hot corrosion tests, Inconel 718, which has been subjected to cyclic hot corrosion, has been found to be more affected by the damage. Similar results were observed in terms of the corrosion products and the damage mechanism.

Keywords

• Hot corrosion; Inconel 718; Na2SO4; V2O5; Molten salt.

Çevrimli ve İzotermal Sıcak Korozyonun Nikel Esaslı Süper Alaşım Malzemeye Etkisi

Abstract

Nikel esaslı süper alaşımlar gaz türbinleri, nükleer reaktörler, jeneratörler gibi geniş bir kullanım alanına sahiptir. Mekanik dayanım ve korozyon direncinin önemli olduğu alanlarda özellikle tercih edilirler. Sıcak korozyon, yüksek sıcaklık uygulamalarında oldukça yıpratıcı bir hasar türüdür. Sıcak korozyonda, erimiş tuzlar reaktif bileşenlerle kolayca reaksiyona girer ve iş parçalarında erken hasara neden olur. Bu çalışmada, nikel bazlı süper alaşım olarak Inconel 718, sıcak korozyon testlerine tabi tutulmuştur. % 50 V2O5-50% Na2SO4 karışımları korozyon bileşeni olarak kullanılmıştır. 900 ° C’ de, 18 saat süreyle çevrimli ve izotermal sıcak korozyon testleri uygulanmıştır. Inconel 718’ de oluşan korozyon ürünleri ve mikroyapısal değişiklikler, sıcak korozyon testlerinden sonra taramalı elektron mikroskobu (SEM), SEM-Enerji Dağılımlı X-Işını (EDX), SEM-haritalaması ve X-Işını Kırınımı (XRD) analizleri ile karakterize edilmiştir.

Keywords

• Sıcak korozyon,Inconel 718,Na2SO4,V2O5,Ergimiş tuz

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