Microstructural and Mechanical Properties of Nd:YAG Laser Welded Dissimilar DP600-DP1000 Steel Sheets

Year 2020, , 155 - 164, 17.03.2020

Oğuz Tunçel , Hakan Aydın , Şükriye Çetin

https://doi.org/10.35414/akufemubid.620768

Cited By: 1

Abstract

In this study, the DP600
and DP1000 steel sheets were joined with the pulsed Nd: YAG (Neodymium-doped
Yttrium Aluminum Garnet (Y3Al5O12)) laser welding and, mechanical and
microstructure properties of the dissimilar welds were experimentally
investigated. As known, there is a demand in modern automotive industry for
performing dissimilar weld of DP steel sheets. In the laser welding operation,
the selection of welding parameters affects the final properties of welds
substantially. So, the main aim of this study was determining the influence of
pulse frequency on the mechanical properties of pulsed Nd:YAG laser welded
DP600-DP1000 steel sheet joints. For this purpose, dissimilar (DP600-DP1000)
steel sheets were double-sided welded with the butt joint. To analyze the
welding performance, microstructural studies, tensile tests and microhardness
measurements were carried out. The weld cross-sections of the joints revealed
three main distinct macrostructural zones: Base metal and heat affected zone of
both steels, and fusion zone. Moreover, a transition zone was observed between
the base metal and heat affected zone on the DP1000 sides. Higher pulse
frequency led to deeper penetration and larger fusion zone and heat affected
zone. The joints welded without any filler wires had macro porosities in the
fusion zones. The tensile properties of the joints significantly increased with
increasing pulse frequency. The tensile properties obtained in this study may
be quite satisfactory for automotive industrial applications. Fusion zone had
the highest microhardness values. However, the lowest microhardness values were
observed in the transition zone on DP1000 side. 

Keywords

DP steels, Nd:YAG laser welding, Dissimilar welding, Pulse frequency, Microstructure

Supporting Institution

Bursa Uludağ Üniversitesi Bilimsel Araştırma Projeleri Birimi

Project Number

HDP (MH) 2017/47

Thanks

The authors thank the Bursa Uludag University Scientific Research Fund for supporting this research (Project No. HDP (MH) 2017/47).

Nd:YAG Lazer Kaynağı ile Birleştirilen Farklı Türdeki DP600-DP1000 Çeliklerinde Mekanik ve Mikroyapı Özellikleri

Abstract

Bu çalışmada DP600 ve
DP1000 çelik sacları darbeli Nd:YAG (Neodymium-doped
Yttrium Aluminum Garnet (Y3Al5O12)) lazer kaynağı ile birleştirilmiş ve farklı
türdeki sacların kaynağında mekanik ve mikro yapı özellikleri deneysel olarak
incelenmiştir. Bilindiği gibi modern otomotiv endüstrisinde farklı türdeki DP
çeliklerimin birleştirilmesinde talep vardır. Lazer kaynak işleminde kaynak
parametrelerinin seçimi kaynak nihai özelliklerini büyük ölçüde etkiler. Bu
yüzden bu çalışmanın amacı  Nd:YAG lazer
kaynağı yapılan DP600-DP1000 çeliklerine kaynak parametrelerinden darbe
frekansının mekanik özelliklere etkilerinin belirlenmesidir. Bu amaçla farklı
türdeki DP600-DP1000 sacları çift taraflı olarak alın kaynağı ile
birleştirilmiştir. Kaynak performansını analiz etmek için mikro yapı
çalışmaları, çekme testleri ve mikro sertlik ölçümleri gerçekleştirilmiştir.
Kaynak kesiti temel malzeme, ısı tesiri altındaki bölge ve ergime bölgesinden
oluşan 3 farklı makro yapısal bölge göstermiştir. Ayrıca DP1000 tarafında ısı
tesiri altındaki bölge ile temel malzeme arasında bir geçiş bölgesi
gözlenmiştir. Yüksek darbe frekansı derin penetrasyon ve daha geniş ergime
bölgesi ve ısı tesiri altındaki bölgeye neden olmuştur. Dolgu teli olmadan
gerçekleştirilen kaynaklar ergime bölgesinde makro gözenekler içermektedir.
Kaynaklı birleştirmenin mukavemeti darbe frekansındaki artışla beraber önemli
ölçüde artmıştır. Bu çalışmada elde edilen çekme mukavemeti özellikleri
otomotiv endüstrisi için oldukça tatmin edicidir. Ergime bölgesi en yükske
mikro sertlik özelliklerine sahiptir. Bunun yanında en düşük mikro sertlik
değerleri DP1000 tarafından temel malzeme ile ısı tesiri altındaki bölge
arasındaki geçiş bölgesinde gözlenmiştir. 

Keywords

DPçelikleri, Nd:YAG lazer kaynağı, Farklı malzemelerin kaynağı, Darbe frekansı, Mikro yapı, Mekanik özellikler

Project Number

HDP (MH) 2017/47

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