IIW White Paper

4 Needs and challenges in welding and joining technologies

Another area of improvement of efficiency is the increase of temperature of combustion in any kind of gas turbines. The related materials, for example Ti-alloys in aircraft engines, Cr-steels in steam turbines or super alloys in the helium driven turbine for the 2020 pebble bed reactor all require special welding processes. These have to be energy efficient and adaptable to the metallurgical needs of the related materials.

Figure 4.7 Bronze-steel or bronze-cast iron combinations are an economic method to produce worm gears (Reproduced courtesy: Probeam)

Welding of heavy gauge sections bears a tremendous potential of materials and energy saving. It should be expected that EB-welding will be the process of choice for such visionary applications, already under development now.

Figure 4.8 Housing of a gas turbine being prepared for EB welding (Reproduced courtesy: Probeam)

An education aspect of the EB welding process will be a serious challenge for coming decades. For successful and wider implementation of the EB welding (which involves high degree of application flexibility) there exists a need for more intense communication and transparency to the potential end-users.

4.3 Repair welds and material response In order to extend service life of aging welded structures, there is need for advanced welding technologies for repair. Most of the repair welding procedures are principally different from welding during fabrication regarding the parameters, the weld sequences as well as the metallurgical conditions and the design features. This means that ideal welding conditions cannot always be achieved during repair welding. Additionally, poor material conditions of the component segments to be repaired might result from previous service operation. Here, advanced welding simulation technologies need to be developed to predict final microstructural conditions and the residual stress state of the repaired area to achieve optimum repair welding procedures and prevent further problems.

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Through Optimum Use and Innovation of Welding and Joining Technologies

Improving Global Quality of Life