Effect of Laser Angle Parameter in High Strength DP1200 Steel Fiber Laser Overlap Welding

Abstract

In this study, high-strength DP 1200 steel plates were welded with fiber laser welding method in the form of overlapping without gaps. The effects of the laser angle (70ᵒ, 80ᵒ, 90ᵒ) changed on the weld bead surface, weld geometry, fracture surfaces and mechanical properties were investigated by keeping the laser power (2500 W), and the scanning speed (55 mm/s) was constant. It has been determined that the rear surfaces of the laser-welded specimens have more spatter effects than the front surfaces. Low level (70ᵒ) or high level (90ᵒ) laser angle was achieved a good result in terms of weld geometry rather than an intermediate level. High strength and relatively high percent elongation values were obtained in the tensile test: the highest shear force was achieved as 5.8266 kN in the sample with a laser angle of 70ᵒ. In addition, the shear force and the fusion zone bonding distance were correlated. Cleavage fractures in specimens produced with a low laser angle (70ᵒ), demonstrated high embrittlement; the fracture surfaces were ductile and the voids formed were small in size in specimens manufactured with a high laser angle (90ᵒ). The high laser angle parameter (90ᵒ) was caused the fraction region to moved away from the weld center and stayed within the Heat Affected Zone (HAZ) region.

Keywords

• Laser welding
• welding parameters
• fracture surface
• mechanical properties
• DP1200 steel

Yüksek Mukavemetli DP1200 Çeliği Fiber Lazer Bindirme Kaynağında Lazer Açısı Parametresinin Etkisi

Abstract

Çalışma kapsamında yüksek mukavemete sahip DP 1200 çelik malzemenin, fiber lazer kaynak işlemiyle birleştirilmesi bindirme formunda yapılmıştır. Lazer gücü (2500 W) ve ilerleme hızı (55 mm/s) sabit tutularak lazer açısı (70ᵒ, 80ᵒ, 90ᵒ) değişiminin kaynaklı bağlantıların kaynak dikiş yüzeyi, kaynak geometrisi, kırılma yüzeyleri ve mekanik özelliklere etkisi incelenmiştir. Lazer kaynaklı numunelerin arka yüzeylerinde, ön yüzeylerine göre sıçrama etkilerinin (spatter effect) daha fazla olduğu tespit edilmiştir. Eşit ısı girdisinde lazer açısının, ara seviyede kullanılmasındansa düşük (70ᵒ) ya da yüksek seviye (90ᵒ) kullanılmasının kaynak geometrisinde optimum sonuçlar vereceği tespit edilmiştir. Çekme testinde yüksek kuvvet ve yüzde uzama değerleri elde edilmiştir: 70ᵒ lazer açısına sahip numunede maksimum kesme kuvveti 5.8266 kN olarak elde edilmiştir. Ayrıca kesme kuvveti ile kaynak geometrisindeki erime bölgesinde ölçülen tam birleşme mesafesi (bonding) arasında ilişki kurulmuştur. Düşük lazer açısı parametresi (70ᵒ) ile üretilen numunelerde yüksek gevrekliğin göstergesi klivaj kırılmalar gözlenmiştir; yüksek lazer açısı (90ᵒ) ile üretilen numunelerde ise kırılma yüzeyleri sünektir, oluşan çukurlar küçük boyutludur. Lazer açısının yüksek dereceye sahip olması (90ᵒ), kırılmanın gerçekleştiği bölgenin Isı Tesiri Altındaki Bölge içerisinde yer almasına neden olmuştur

Keywords

• Lazer kaynak
• kaynak işlem parametreleri
• kırılma yüzeyi
• mekanik özellikler
• DP1200 çeliği

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