Çift fazlı çeliklerin nokta direnç kaynağı ile birleştirilmesinde akım etkisi

Öz

Nokta direnç kaynaklı birleştrimelerdeki akım değerinin mekanik ve metalurjik özellikler üzerindeki etkisi galvanizli farklı kalınlıklardaki DP600 çelik saclar kullanılarak deneysel olarak incelenmiştir. Numuneler 1.5 ve 1.8 mm kalınlıklarda seçildi. Kaynak proses parametreleri, 5 kN elektrod kuvveti, 7, 9, 11, 13, 15 kA kaynak akım değerleri,180, 240, 300, 360 ve 420 ms kaynak süreleri tercih edilerek gerçekleştirilmiştir. Kaynak birleştirmeli numuneler, en yüksek çekme mukavemetinin belirlenmesi için çekme-makaslama testine tabi tutuldu. Optimal numuneler optik mikroskop ve taramalı electron mikroskobu ile incelendi. Nokta kaynağı değişkenlerinin maksimum dayanım üzerindeki etkisi belirlendi, akım-süre değerlerini gösteren lobe diyagramı elde edildi. Optimum kaynak parametreleri yeni saclarda başarıyla uygulandı. Deneysel sonuçlar gösterdi ki; kaynak akımı özellikle çarpışma enerjisi emiliminde ve yük taşıma kapasitesinde önemli bir rol oynamaktadır.

Anahtar Kelimeler

• Otomotiv gövde
• Çift fazlı çelik
• Enerji emme kapasitesi
• Nokta direnç kaynağı
• Kaynak hata tipleri

The effect of current on the resistance spot welding of dual phase steels

Abstract

The effect of current on resistance spot welding joints on metallurgic and mechanical properties is investigated experimentally using galvanized unequal-thickness DP600 steel sheets. The specimens were chosen to be 1.5 and 1.8 mm thicknesses. The parameters of the welding process were preferred as an electrode force at 5 kN, welding currents at 7, 9, 11, 13 and 15 kA and welding times at 180, 240, 300, 360 and 420 ms. The welded joint specimens were subject to tensile-shear strength testing to determine the ultimate tensile strength. Optimal specimens were inspected using optical microscopes and scanning electron microscopy. The effect of spot welding variables on the ultimate tensile strength was determined and the lobe diagram, which shows optimal current-time values, was obtained. The optimal welding parameters were carried out on new sheet metals successfully. The experimental results show that the welding current plays an important role in the especially crash energy absorption and load-carrying capability.

Keywords

• Automotive body
• Dual phase steel
• Energy absorption capability
• Resistance spot welding
• Weld failure types

Kaynakça

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