Investigation of the Effects of Cold Forming Applied to AA 2024-T3 Materials on T8 Heat Treatment

Abstract

The use of aluminum alloys in the aviation and space industry has an important place. Among these materials, AA2024 alloy is used especially in the main fuselage and beams of aircraft, as well as in connection and rivet materials. Since the strength of these alloys is low in their non-heat-treated form, the materials are strengthened by cold forming and heat treatment processes. In this study, AA2024-T3 materials were cold formed at room temperature at 30°, 45°, 60°, 75° and 90° angles and heat treatment were applied in order to bring them to T8 condition. The properties of the materials were examined in both T3 heat treatment condition and T8 condition after heat treatment. The microstructures of the alloys were examined with both optical and scanning electron microscopes. In addition, the changes in the microhardness and electrical conductivity properties of the alloys were also investigated. In the T3 materials that underwent the forming process, an increase in the average grain size occurred as the forming angle increased. In addition, a slight increase in the hardness values was also achieved. In the analyses performed on the materials in the T8 heat treatment condition, homogeneous grain sizes independent of form and high hardness values were obtained. In the microstructure analyses in the T8 heat treatment condition, it was observed that twin structures were formed between the grains.

Keywords

• Cold Forming
• AA2024
• Heat Treatment
• Microstructure
• Hardness

AA 2024-T3 Malzemelere Uygulanan Soğuk Şekillendirmenin T8 Isıl İşlemine Olan Etkilerinin İncelenmesi

Abstract

Havacılık ve uzay endüstrisinde alüminyum alaşımlarının kullanımı önemli bir yer tutmaktadır. Bu malzemelerden AA2024 alaşımı, özellikle uçakların ana gövde ve kirişlerinde, bağlantı ve perçin malzemelerinde kullanılmaktadır. Bu alaşımların ısıl işlem uygulanmamış haliyle mukavemetleri düşük olduğu için, soğuk şekillendirme ve ısıl işlem prosesleri ile malzemelere mukavemet kazandırılmaktadır. Bu çalışmada, AA2024-T3 malzemelere oda sıcaklığında 30°, 45°, 60°, 75° ve 90°’lik açılarında soğuk şekillendirme yapılıp, T8 ısıl işlem koşuluna getirmek amacıyla ısıl işlem uygulanmıştır. Malzemelerin özellikleri hem T3 ısıl işlem koşulunda hem de ısıl işlem sonrası T8 koşulunda incelenmiştir. Alaşımların mikroyapıları hem optik hem de taramalı elektron mikroskopları ile incelenmiştir. Ayrıca, alaşımların mikrosertlik ve elektriksel iletkenlik özelliklerindeki değişimleri de araştırılmıştır. Form işlemi yapılmış T3 malzemelerde form açısı arttıkça ortalama tane boyutunda artış meydana gelmiştir. Ayrıca, sertlik değerlerinde de bir miktar artış sağlanmıştır. T8 ısıl işlem koşulundaki malzemelerde yapılan analizlerde ise form açısından bağımsız homojen tane boyutları ve yüksek sertlik değerleri elde edilmiştir. T8 ısıl işlem koşulundaki mikroyapı analizlerinde tanelerde ikizlenme yapılarının oluştuğu gözlenmiştir.

Keywords

• Soğuk İşlem
• AA2024
• Isıl İşlem
• Mikroyapı
• Sertlik

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