Twin spot laser welding for dissimilar thickness steel tailored blanks

TWI Industrial Member Report Summary 793/2004 

Chris Allen looks at two spot laser welding of tailored blanks

Background

Tailored blanks are made up of metal sheets of different thicknesses, alloy grades and/or coating types, which are cut to size, butted up and welded together to form blanks for pressing, usually to form automotive body panels. Laser butt welding is an established process for the manufacture of steel tailored blanks.

However, two of the disadvantages in autogenous laser welding of tailored blanks are the inability to bridge gaps >0.1-0.2mm or underfill.

This work addresses the application of 'dual focus' or 'twin spot' laser technology to improve both gap bridging ability and weld bead profile.

Objectives

The objective for the project was to determine the optimum twin spot configuration for autogenous Nd:YAG laser welding of linear butt welds in zinc-coated steels of dissimilar thickness, in terms of the maximum gap bridging ability and smoothest weld bead profile.