Investigation of Microstructure, Hardness and Acidic Corrosion Properties of TIG Welded Ti6Al4V Titanium Alloy

Abstract

Titanium alloys are used in many areas due to their superior properties. Welding can be done in the manufacturing processes made of these alloys or afterwards. In this study, microstructure, hardness and acidic corrosion properties of Ti6Al4V titanium alloy joined by welding were investigated. Since the titanium alloys parts can be used in chemical, petrochemical and similar fields in acidic environments, the corrosion properties have been examined in acidic environment. In the study Ti6Al4V titanium alloy parts were joined by Tungsten Inert Gas (TIG) welding method. The microstructures were examined by optical microscope, and hardness tests were performed using the Vickers method. Electrochemical corrosion experiments were performed by using potentiodynamic method to determine the corrosion behavior in acidic environment. According to the results of the microstructure, it was observed that a good combination was achieved between Ti6Al4V titanium alloy parts by TIG welding and the weld metal consisted of both thin and long morphology α phase grains and very large sized β phase grains. The hardness increased in the heat affected zone and weld metal than base metal. The corrosion rate of TIG welded titanium alloy in acidic environment was higher than the unwelded titanium alloy.

Keywords

• Titanium
• welding
• microstructure
• hardness
• corrosion

TIG Kaynak Yöntemi ile Birleştirilen Ti6Al4V Titanyum Alaşımının Mikroyapı, Sertlik ve Asidik Ortamdaki Korozyon Özelliklerinin İncelenmesi

Abstract

Titanyum alaşımları, üstün özellikleri nedeni ile birçok alanda kullanılmaktadır. Bu alaşımlardan yapılan imalat işlemlerinde veya sonrasında kaynak ile birleştirme yapılmaktadır. Bu çalışmada kaynak ile birleştirilen Ti6Al4V titanyum alaşımının mikroyapı, sertlik ve asidik ortamdaki korozyon özellikleri incelenmiştir. Asidik ortamdaki korozyon özelliğinin incelenmesinin amacı, kaynaklı titanyum alaşımlarından yapılan imalatların kimya, petrokimya ve benzeri alanlarda asidik ortamlarda kullanılmasıdır. Ti6Al4V titanyum alaşımının kullanıldığı çalışmada Tungsten İnert Gaz (TIG) kaynak yöntemi ile birleştirme yapılmıştır. Optik mikroskop ile mikroyapılar incelenmiş, Vickers yöntemi ile sertlik testleri yapılmıştır. Asidik ortamdaki korozyon davranışının belirlenmesinde potansiyodinamik yöntem ile elektrokimyasal korozyon deneyleri uygulanmıştır. Mikroyapı sonuçlarına göre TIG kaynağı ile Ti6Al4V titanyum alaşımı parçalarda iyi bir birleşmenin gerçekleştiği, kaynak metalinin hem ince uzun morfolojide asiküler α fazı hem de büyük boyutlu β fazı tanelerinden oluştuğu görülmüştür. Isı tesiri altındaki kaynak bölgesinde kaynak metaline yaklaşıldıkça sertlik artmıştır. Kaynak metali sertliği de esas metale göre oldukça yüksektir. TIG kaynaklı titanyum alaşımının asidik ortamdaki korozyon hızı kaynaksız titanyum alaşımına göre daha yüksek olmuştur.

Keywords

• Titanyum
• Kaynak
• Mikroyapı
• Sertlik
• Korozyon

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