AA6061 T6 Alüminyum Alaşımının Geri ve İleri Ekstrüzyonu Sırasında Hız ve Basıncın Kalıntı Gerilmeler Üzerine Etkisi

Abstract

Ekstrüzyon işlemi, alternatif üretim tekniklerine kıyasla maliyet açısından etkili bir üretim yöntemi olarak kabul edilir ve mükemmel mekanik özellikler ve yüksek ürün kalitesi sunar. Kombine ekstrüzyon, ek işlem adımlarına olan ihtiyacı en aza indirerek verimliliği daha da artırır, böylece zamandan tasarruf sağlar ve üretim maliyetlerini azaltır. Kalıp geometrisi ve sürtünme faktörleri, bu işlemin başarısını ve kalitesini belirlemede kritik bir rol oynar. Bu çalışmada, birleşik geri-ileri ekstrüzyon işlemini araştırmak ve hız ve basınç gibi işlem parametrelerinin ekstrüde ürünlerde oluşan kalıntı gerilmeler üzerindeki etkisini incelemek için kütük malzemesi olarak alüminyum alaşımı AA 6061 T6 seçilmiştir. İki zımba tipi kullanılmıştır: geri ekstrüzyon yönü için altıgen zımba ve ileri ekstrüzyon yönü için kare zımba. Her zımba tipi için, presleme basıncının kalıntı gerilmeler üzerindeki etkisini değerlendirmek için üç farklı kesit alanı (140, 130, 115 mm2) ve üç farklı şekillendirme hızı (0.25, 0.5, 1 mm/s) ) test edilmiştir. Deneyler, yağlanmış koşullar altında hidrolik pres altında ısıl işlem görmüş bir H13 çelik kalıp kullanılarak gerçekleştirilmiştir. Bulgular, presleme basıncında bir azalmaya karşılık gelen zımbanın kesit alanının artırılmasının, sabit bir hızda daha yüksek kalıntı gerilimlerle sonuçlandığını göstermektedir. En yüksek kalıntı gerilimler (1315 MPa), geriye doğru ekstrüzyon işlemine karşılık gelen altıgen bölgede gözlemlenmiştir. Geri ve ileri ekstrüzyon yönleri arasındaki orta bölgelerde ara gerilim seviyeleri (<990 MPa) bulunurken, en düşük kalıntı gerilimler (<588 MPa), kare zımba ile ilişkili olan ileri ekstrüzyon bölgesinde kaydedilmiştir.

Keywords

• birleşik ekstrüzyon
• alüminyum alaşımı
• kalıntı gerilim
• anahtar soketi

The Influence of Velocity and Pressure on Residual Stresses During The Backward and Forward Extrusion of AA6061 T6 Aluminium Alloy

Abstract

The extrusion process is considered a cost-effective manufacturing method compared to alternative production techniques, offering excellent mechanical properties and high product quality. Combined extrusion further enhances efficiency by minimizing the need for additional processing steps, thereby saving time and reducing production costs. The die geometry and friction factors play a critical role in determining the success and quality of this process. In this study, AA 6061 T6 aluminium alloy was selected as the billet material to investigate a combined backward–forward extrusion process and to examine the influence of process parameters, such as velocity and pressure, on the residual stresses formed in the extruded products. Two punch types were utilized: a hexagonal punch for the backward extrusion direction and a square punch for the forward extrusion direction. For each punch type, three different cross-sectional areas (140, 130, 115 mm2) and three different forming velocities (0.25, 0.5, 1 mm/s) were tested to assess the effect of forming pressure on residual stresses. The experiments were conducted using a heat-treated H13 steel die with a hydraulic press under lubricated conditions. The findings indicate that increasing the cross-sectional area of the punch, which corresponds to a reduction in pressing pressure, results in higher residual stresses at a constant velocity. The highest residual stresses were observed in the hexagonal region (1315 MPa), corresponding to the backward extrusion process. Intermediate stress levels (<990 MPa) were found in the middle regions between the backward and forward extrusion directions, while the lowest residual stresses (<588 MPa) were recorded in the forward extrusion region, associated with the square punch.

Keywords

• combined extrusion
• aluminum alloy
• residual stress
• wrench socket

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