Mechanical and Microstructural Investigations of the Laser Welding of Different Zinc-Coated Steels

Eva Zdravecká,Ján Slota

doi:10.3390/met9010091

Abstract

Tailor welded blanks (TWB) represent an anisotropic and non-homogenous material. The knowledge of the mechanical properties and microstructure of the fusion zone and heat-affected zone (HAZ) obtained with laser welding is essential to ensure the reliability of the process. In this paper, laser-welded hot-dip Zn-coated low carbon microalloyed steels with different thickness and mechanical properties were used. The mechanical properties of the laser-welded blanks were determined by tensile tests and formability by Erichsen cupping tests. In addition, the pore formation during the laser welding process was analyzed. The microstructural analysis confirmed the formation of the favorable structure of the weld metal and the heat-affected zone without the presence of martensite. The obtained results showed that it is possible to produce TWBs with suitable mechanical properties by laser welding.

Highlights

Laser beam welding is very flexible because welds can be made in continuous and complex shapes, can be performed at relatively high travel welding speeds, and can achieve deeply penetrated welds
Combinations of hot-dip zinc coated low carbon steel sheet DX53D+Z with DX54D+Z interstitial-free (IF) steel sheets marked as TWB1 were used
Characterization of the Laser were section photo of the microstructure laser-welded steel sheets (DX54D+Z—0.8 microstructure of laser-welded steelof sheets (DX54D+Z—0.8 mm/DX53D+Z—1.0 mm) mm/DX53D+Z—1.0 marked as TWB1 properties obtained in different welding zones function the the mm)ismarked asmechanical

Summary

Introduction

Laser beam welding is very flexible because welds can be made in continuous and complex shapes, can be performed at relatively high travel welding speeds, and can achieve deeply penetrated welds. Tailor welded blanks (TWB) are blanks that have been manufactured from sheets with similar or different thicknesses by a welding process. The laser is preferred for welding owing to the high speed of the process, low distortion due to the small heat-affected zone, the manufacturing flexibility, and the ease of automation [1,2,3,4,5]. Designers are able to tailor the location in the blank where specific material properties are desired when creating a TWB. This trend of welding and forming of sheet-metal pieces allows notable flexibility in product design, structural stiffness, and crash behavior (crashworthiness)

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Results

Conclusion