# Study on Mechanical Properties of Adjustable-Ring-Mode Laser Scanning Welding of TA1 Titanium Alloy to 304 Stainless Steel Dissimilar Thin Sheets

## TL;DR

This study examines how adjustable-ring-mode laser welding affects the strength of titanium alloy and stainless steel thin sheets joined with magnesium alloy.

## Contribution

The study introduces adjustable-ring-mode laser welding parameters that optimize the mechanical properties of dissimilar metal joints.

## Key findings

- Welded joints showed average tensile strengths over 80% of the filling material when ring power was 800–1000 W or scanning frequency was 100–200 Hz.
- Maximum tensile strength reached 281.2 MPa, equivalent to 93.7% of the AZ61S filler material.
- Higher energy conditions led to decreased joint strength due to interface layer thickening and Fe concentration changes.

## Abstract

The adjustable-ring-mode (ARM) scanning laser was used to perform butt welding on 0.5 mm thick TA1 titanium alloy and 304 stainless steel (SS304) thin sheets, with 1.2 mm diameter AZ61S magnesium alloy welding wire as the filling material. Microhardness test results show that the hardness distribution presented a trend of being higher in the base metals on both sides and lower in the middle filling area, with no hardening observed in the weld zone. For all specimens subjected to horizontal and axial weld bending tests, the bending angle reached 108° without any cracks occurring. When the ring power was in the range of 800–1000 W, or the scanning frequency was between 100 and 200 Hz, all the average tensile strengths of the welded joints were more than 80% of that of the AZ61S filling material (approximately 240 MPa); the maximum average tensile strength stood at 281.2 MPa, which is equivalent to 93.7% of the AZ61S. As the ring power or scanning frequency increased further, the tensile strengths of the joints showed a decreasing trend. The remelting effect of the trailing edge of the ARM laser under high energy conditions, or the scouring of the turbulent molten flow induced by the scanning beam, damages the weak links at the newly formed solid–liquid interface and increases the Fe concentration in the molten pool. This leads to a thicker FeAl interface layer during growth, thereby resulting in a decline in the mechanical properties of the welded joints.