TWI Industrial Member Report Summary 456/1992
By I A Jones
Laser welding offers a low heat input welding process which can produce deep penetration, narrow welds at high joining rates which impart low distortion to the component. Previous work has shown that wire feed can be used with laser welding without significant processing difficulties. The use of wire feed allows gaps at the joint to be filled and also control of the weld metal composition and hence weld metal properties. The majority of work to date has concentrated on the addition of cold, solid wires which are readily available.
The aim of this work was to use metal cored wires of controlled composition to investigate the effect of specific elements on the weld metal properties. Also within this work, a process for feeding hot wire into the weld was developed, and the effects of the use of hot wire on the welding process and weld metal properties were examined. In the reported work a 10kW CO2 laser was used to weld 12mm thick structural steel (BS4360 Grade 50D). Specially manufactured metal cored wires of 1.2mm diameter, containing a range of titanium (0 - 0.06wt%) and oxygen (300 - 1500ppm) contents were used to fill weld gaps of 1.8mm. Each wire type was used to make welds using both cold and heated wire. The welds were evaluated in terms of porosity content, hardness and impact toughness properties.