PROJECT NAME:	Improvement in Steel Utilization and Manufacturing by Recent Break-through in High-power Fibre Laser Welding
	ACRONYM:	FIBLAS
	FUNDED BY	European Commission, Research Fund for Coal and Steel
	CONTRACT No.	RFSR-CT-2006-00029

In European heavy industry applications such as oil and gas transportation, shipbuilding and heavy construction, high strength steel grades are of considerable and still increasing importance. Aside from weight saving aspects, demands such as high toughness at a wide range of temperature are of crucial importance for these applications. Although the use of conventional welding techniques such as GMA welding for the production of heavy industry structures from such steels is a fully developed technology, there still remain some major disadvantages both in view of technological and economic aspects.

These disadvantages are due to a comparably high heat input of such welding processes. E.g. distortion, which causes high straightening efforts and residual stresses at the joint area, is s significant factor that needs to be taken into account. Moreover, welding speeds of conventional welding processes are rather low, which is a special disadvantage in continuous processes such as pipe production or pipelaying. To improve this uncompetitive and high-cost situation of the conventional technology, laser or laser GMA hybrid welding processes - as fast welding processes with low heat input - have already been considered. However, as standard laser systems (CO2 or Nd:YAG) which have long been industrially available are generally characterised by high weight, low energy efficiency and less robustness. Therefore, their wide-spread applications were significantly limited in various major European heavy industry applications.

This situation has changed with the recent development of industrial high-power fibre laser systems, which potentially overcome these limitations due to their specific properties and are considered to be the first truly mobile laser systems even under rough field conditions. As it is well-known that Europe has a leading position not only in laser source manufacturing, but also in their application for materials processing in various industrial sectors, this project is planned to maintain and further strengthen this position by adopt the innovations and new technological developments in the field of fibre laser beam welding technology.

However, due to the novelty of the high-power fibre laser systems, industrial experience in welding high-strength construction steels is still lacking. The current situation is further complicated with the lack of the fundamental understanding of the joint quality of such high-power fibre laser welds with respect to metallurgy and mechanical / fracture performance of the joints. This is especially disadvantageous, as, due to metallurgical reasons, the mechanical properties of these steel grades (especially such advanced grades as X100 or even higher) such as fracture toughness at low temperatures tend to deteriorate if they are subjected to inappropriate time-temperature cycles during welding. Consequently, optimum process and joint design has to be considered and optimised in view of these challenges to fabricate safe and cost-effective / competitive steel components with long service life based on excellent properties.

Main goals of the project are to:

• provide new high-power fibre laser and laser GMA hybrid welding processes suitable for heavy industry applications under field conditions
• enable an increased use of newly developed high strength steels in the heavy industries
• improve design and weld performance and reduce rework

Expected benefits:

• Significantly reduced production cost by increased use of high-power fibre laser welding in heavy industries
• Fundamental knowledge on the metallurgical and mechanical weld seam properties of high-power fibre laser welded high-strength steel sheet and pipe structures.
• Weld joint “material data base” for design and use of high strength steel components accompanied with the wide plate fracture test results.
• Increased use of high-strength steels to gain benefit of both cost-saving and raw material saving aspects.