The results obtained on new materials are a start point of introducing MIG/MAG welding in pressure vessels fabrication. Chemical compositions of 8MnNimo y 2,25 Cr1Mo steels have been improved for MIG/MAG welding. In the case of the first material, it is possible to avoid the post welding heated treatment (PWHT). Results have been obtained both on the weld quality and seam geometry according to the gas, wire and welding parameters used. On the other hand, the welding sequence has been obtained in order to minimise the residual stresses.
The welding procedures developed by the users have been validated within the process control. There is available a quality register capable of monitoring, supervising and registering the welding session, in real time.
There is currently a prototype system for the welding process. This prototype has been used during the user tests beds. It consists of an articulated robot integrated with a triaxial manipulator, with a sensorised welding torch. The cell controller and the quality register are two separate platforms which continuously indicate the operator the current situation of the welding cell and relevant information on the welding session.
The aim of this research is to improve and set a new process for multilayer welding in long-cycle parts, specially boilers manufacturing, where the asymmetry problem is added.It is also important the great thickness of the parts(even above 100 mm)and the fact that surfaces of the joint are not machined but flame-cut.Great improvements could be done in this work through a deep research in the welding materials, procedures and methodology, specially focusing this welding process research from the point of view of the new capabilities introduced by the automation.
So, this project will cover this main activities:
- Two enhanced steel alloys and new welding methods.This will include the influence of residual elements and welding parameters in the wettability, and sequence optimization to minimize the residual stresses and cracking when working under heat.This last point will also reducing the lead-time through reducing/eliminating Post Weld Heat Treatments.
- Improvements reached through automation in the welding process, covering the gap between the existing mulpipass welding automation tools and the pools required for this process(sensor, path generator, mechanical devices and their interfaces).
- Development of a robotized prototype as a test-bench for the new welding process for enhanced steel alloys and a quality assurance system for this process.
- An intensive test and improvement of the systems in real work on the shop floor of the users.
Funding SchemeCSC - Cost-sharing contracts
71202 Le Creusot
92084 Paris La Defense