The Effects of the Electrode Type on Microstructure and Hardness of the RSW of DP600 Steel

Öz

In this paper, the effects of the electrode type on microstructure and hardness of the resistance spot welded junctions of DP steel were studied. Commercial galvanized DP sheet steel was used. Resistance spot welding (RSW), with changing electrode type according to geometry, has been carried out with constant weld time, weld current and weld pressure. Microstructure and hardness are depending on materials properties and weld parameter particularly heat input. Heat input is resulted from welding condition and parameters. Electrode tip type effects welding contact and heat transfer during RSW. Results showed that particularly spherical type electrode showed low heat input thus limited microstructure changing at heat affected zone. This have on positive effect on properties of the junctions. Depending on chemical composition of DP 600 harder phases generally formed at weld zone.

Anahtar Kelimeler

• DP,RSW,microstructure,hardness

Elektrot Tipinin Nokta Direnç Kaynaklı DP600 Çeliğinin Mikroyapı ve Sertliğine Etkileri

Öz

Bu çalışmada, elektrot tipinin DP çeliğinin nokta direnç kaynaklı birleşimlerinin mikroyapı ve sertliği üzerindeki etkileri incelenmiştir. Ticari galvanizli DP sac çeliği kullanılmıştır. Nokta direnç kaynağı (NDK), geometriye göre değişen elektrot tiplerinde, sabit kaynak süresi, kaynak akımı ve kaynak basıncında gerçekleştirilmiştir. Mikroyapı ve sertlik malzeme özellikleri ve özellikle ısı girdisi olmak üzere kaynak parametrelerine bağlıdır. Isı girdisi, kaynak şartları ve parametrelerinden kaynaklanmaktadır. Elektrot uç tipi NDK süresince kaynak teması ve ısı transferini etkilemektedir. Sonuçlar, özellikle küresel tip elektrotun düşük ısı girdisi meydana getirdiğini, dolayısıyla ısıdan etkilenen bölgede sınırlı mikroyapı değişiminin olduğunu göstermiştir. Bu durum, birleşimlerin özellikleri üzerinde pozitif etkiye sahiptir. DP600 çeliğinin kimyasal bileşimine bağlı olarak kaynak bölgesinde genellikle daha sert fazlar meydana geldiği görülmüştür.   

Anahtar Kelimeler

• DP,DP,NDK,mikroyapı,sertlik

Kaynakça

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