TWI Industrial Member Report Summary 1028/2012
By C M Allen
A number of industries (including the oil and gas sector and power generation sectors) require welding processes for the high quality, high productivity, low distortion welding of thick section steels and stainless steels, eg for pipe joining or pressure vessel manufacture. To this end, multi-pass narrow gap arc welding techniques have been developed, but the productivity of these techniques can be an issue. Electron beam (EB) welding is capable of thick section welding in a single-pass, but the requirement for welding in a vacuum can dissuade some potential users from its adoption.
Section thicknesses much beyond 25mm are still outside the out-of-vacuum single-pass capabilities of laser welding, for all but the highest power lasers. However, lasers can and have been used for narrow gap multi-pass welding, in a higher productivity analogue of narrow gap arc welding. With the increases in beam power, power density (through reduced focused spot size) and stand-off distance offered by modern fibre and disk lasers, further advances in the capabilities of lasers for such multi-pass welding are undoubtedly possible, and these are explored in this report.
- Develop parameters for high quality multi-pass fibre-delivered laser welding of thick section (25mm) steel.
- Determine suitable welding parameters maximising joint completion rate.