SÜRTÜNME KARIŞTIRMA KAYNAĞI İLE BİRLEŞTİRİLMİŞ BAĞLANTILARDA PİM ÇAKIŞMASININ MEKANİK ÖZELLİKLER ÜZERİNE ETKİSİ

Year 2018, , 917 - 928, 20.07.2018

Şefika Kasman Sertan Ozan

https://doi.org/10.28948/ngumuh.445390

Abstract

Bu çalışmada, AA-7075 T651 alüminyum alaşımlı plakaların sabit bir pim
ofset mesafesi ve iki farklı ofset yönü ile üst üste bindirilmiş iki kaynak
dikişi için mekanik özelliklerindeki değişimler araştırılmıştır. Herhangi bir
ofset olmaksızın plakaların temas yüzeyinde gerçekleştirilen tek kaynak
dikişinin mekanik özellikleri ile karşılaştırma yapılmıştır. Ayrıca kaynaklı
bağlantılar için mikroyapısal incelemeler yapılarak kaynaklı bağlantılardaki
kusurlar ve pim karıştırma bölgesine ait tane yapısındaki değişimler
araştırılmıştır. Deneysel verilerin değerlendirilmesi sonucunda en yüksek çekme
mukavemeti olan 423 MPa, 400 dev/dak takım dönme hızında ve herhangi bir
çakışmanın olmadığı tek kaynak dikişine sahip kaynaklı bağlantıdan elde
edilmiştir. Bu koşul için ölçülen birim uzama %10 iken, en yüksek birim uzama
değeri %12,5, 400 dev/dak ve pim ofset yönü olarak pimin dönüş yönünün
seçildiği kaynaklı bağlantıdan elde edilmiştir. En yüksek mukavemet ve birim
uzama (%) değeri üç farklı pim ofset yönü için de takım dönme hızının 400
dev/dak olduğu durumda elde edilmiştir. Takım dönme hızındaki artış ile çekme
dayanımında ve birim uzama (%) değerinde azalma meydana geldiği ortaya
çıkmıştır.

Keywords

Sürtünme karıştırma kaynağı, pim çakışması, mekanik özellikler, mikroyapı

EFFECT OF PIN OVERLAP ON MECHANICAL PROPERTIES OF FRICTION STIR WELDED JOINTS

Abstract

In this study, the changes in mechanical properties of AA-7075 T651
aluminum alloy plates for a fixed pin offset distance and two overlapping weld
seams with two different offset directions were investigated. Comparisons were
made with the mechanical properties of the single weld seam formed on the
contact surface of the plates without any offset. In addition, microstructural
observations of welded joints were carried out to investigate the defects in
welded joints and the changes of grain structure in the nugget zone. As a
result of evaluation of the experimental data, the highest tensile strength,
423 MPa, was obtained from the welded joint with single weld seam which was
manufactured with a tool rotational speed of 400 rpm and without any pin
overlap. The elongation at rupture for this condition was measured to be 10%,
while the highest elongation at rupture, 12.5%, was obtained from the joint
welded with a tool rotational speed of 400 rpm and where AS was selected as the
pin offset direction. The highest strength and elongation at rupture (%) for
all three different pin offset directions were obtained with the tool
rotational speed of 400 rpm. It was revealed that with the increase in tool
rotational speed, both tensile strength and elongation at rupture (%)
decreased.

Keywords

Friction stir welding, pin overlap, mechanical properties, microstructure

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