The objective is to improve the technology, and hence European industrial exploitation, of low input welding by three significant, interlocking advances in weld properties, process sensors and expert systems.
The project has concentrated on three types of materials, C/Mn steels, Stainless steel and Ti-alloys. The work on weld properties have shown improvements to hardness and toughness as thermal cycle effects and compositional effects have been investigated and quantified. Investigations into compositional effects have led to specification of compositional guidelines of C/Mn steels in order to reduce shrinkage cavity problem associated with laser welding in thick plates at high speed. An alternative charpy test has been proposed in order to overcome the problems related to weldmetal/parent material strength mismatch. For all materials investigated, optimised welding procedures were elaborated and used for welding of industrially relevant components.
The sensor work involved novel research and development of two ultrasonic sensors, one for on-line measurement of the weld liquid/metal interface thereby quantifying weld size and penetration, and one for on-line defect monitoring.
Innovative work on expert system for monitoring and control of the laser welding operation have been carried out, incorporating rule based information from the weld properties work and sensor input from an commercially available seam tracking system and the ultrasonic sensors.
A demonstration of the pre-prototype Monitoring and Control Expert System was carried out at one of the partners premises. The components of the total system was refined and integrated to an extend that the functionality of the pre-prototype monitoring and control system could be demonstrated.