Properties Evaluation of the Welded Joints Made by Disk Laser

Area of Science:

• Materials Science
• Metallurgy
• Manufacturing Engineering

Background:

• Advancements in automotive manufacturing require high-strength steels with excellent weldability.
• Laser welding offers precision and efficiency for joining advanced steel grades.
• Understanding weld microstructure and properties is crucial for structural integrity.

Purpose of the Study:

• To investigate the laser welding process for HSLA, DP600, and TRIP steels.
• To analyze the microstructure and mechanical properties of the resulting welds.
• To establish correlations between microstructural features and weld performance.

Main Methods:

• Laser welding of 0.78-0.81 mm thick double-sided hot-dip galvanized sheets.
• Microstructural analysis using optical microscopy to identify phases.
• Mechanical testing, including hardness and tensile strength measurements.

Main Results:

• Successful welds were achieved without weld zone pretreatment.
• Weld zones showed martensitic and ferritic phases due to high cooling rates.
• Weld hardness was highest in the alloyed region; a narrow soft zone was observed in the HAZ.
• Ultimate tensile strength of welds exceeded base metal strength for all investigated steels.

Conclusions:

• Laser welding is effective for joining HSLA, DP600, and TRIP steels.
• The microstructure, characterized by martensite and ferrite, provides high weld strength and adequate ductility.
• The established relationship between microstructure and mechanical properties aids in optimizing welding parameters for these advanced steels.