AA7075-T6 ve AZ31B Alaşımlarının Sürtünme Karıştırma Kaynağı Üzerinde Ön Isıtma ve Kuru Buz Soğutmasının Etkisi

Year 2019, Volume: 22 Issue: 3, 655 - 663, 01.09.2019

Musa Bilgin , Şener Karabulut , Ahmet Özdemir

https://doi.org/10.2339/politeknik.426649

Abstract

Bu çalışmada,
AA7075­T6 alüminyum ve AZ31B magnezyum alaşımlarının sürtünme karıştırma kaynak
(SKK) yöntemi ile kaynak edilebilme özelliği araştırılmıştır. Farklı kimyasal
ve mekanik özelliklere sahip alüminyum ve magnezyum alaşımlarını sürtünme
karıştırma kaynağı ile birleştirebilmek için sabit devir, sabit tabla ilerleme
hızı, farklı takım kaydırma değerlerinde, numunelere ön ısıtma ve kuru buz ile
soğutma işlemleri uygulanarak dört farklı kaynak işlemi yapılmıştır. Birleştirilmiş
numunelerin kaynak kalitesi, tahribatlı ve tahribatsız muayene yöntemleri kullanılarak
değerlendirilmiştir. Alüminyum alaşımına uygulanan ön ısıtmanın ve kaynak
işlemi sırasında uygulanan kuru buz ile soğutmanın mekanik ve mikro yapısal
özellikler üzerindeki etkisi incelenmiştir. Test sonuçları, önceden ısıtılmış
ve kaynak işlemi sırasında kuru buz ile soğutulmuş kaynaklı numunelerinin çekme
dayanımının daha yüksek olduğunu göstermiştir. Ön ısıtma işlemine tabi tutulmuş
numunelerin kaynak yüzeyinde gözenek oluşumu görülürken, kuru buz ile soğutma
yapılarak birleştirilen numunenin kaynak hattında boşluk oluşumu gözlenmiştir. Normal
kaynaklı numunelere kıyasla, ön ısıtma ve kuru buz soğutma işlemine tabi
tutularak birleştirilmiş numunelerin karıştırma bölgesinde homojen bir karışım
elde edilmiştir. 

Keywords

AA7075, AZ31B, sürtünme karıştırma kaynağı, ön ısıtma, kuru buz soğutma, mekanik özellikler, mikro yapı

Effect of Preheating and Dry Ice Cooling on Dissimilar Friction Stir Welding of AA7075-T6 and AZ31B

Abstract

In this study, dissimilar friction stir welding
behavior of AA7075-T6 aluminum and AZ31B magnesium alloys were investigated.
Aluminum and magnesium alloys were joined by friction stir welding under four
welding conditions and in two environments, namely pre-heated aluminum and dry
ice for cooling, with tool rotation of 1120 rpm, table speed of 20 mm/min and
two different tool offset values. The welding quality of the joined specimens
were evaluated by employing destructive and non-destructive testing methods.
The influence of the pre-heating applied to the aluminum alloy and employing ice
cooling during the welding process on the mechanical and microstructural
properties were examined. The test results showed that the higher tensile
strength values were obtained from welded specimens of the pre-heated and
cooled by dry ice during the welding process. Porosities were seen on the
welded surface of the pre-heated specimen while the cavities were observed on
the joint line of the cooled specimen using dry ice during the process. A
homogenous material mixing was achieved in the stir zone of the welded
specimens subjected to pre-heating and dry ice cooling process compared with
the normal welded specimens.

Keywords

AA7075, AZ31B, friction stir welding, pre-heating, dry ice cooling, mechanical properties, microstructure

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