IIW White Paper

Furthermore, in the field of dissimilar combinations of metallic, ceramic and carbon-carbon materials, the following areas are creating challenges. Technologies for joining (welding) the above materials by using new pulsed heating methods, electromagnetic or mechanical effects, and hybrid solid-state joining processes. New welding consumables in the form of films, foils, powders and pastes, including multilayer foils, capable of entering into reaction of high-temperature synthesis of intermetallic phases in local volumes (spaces). Building of new types of structures from materials with a minimal specific weight, i.e. foam materials, sandwiches, dissimilar compositions, volumetric billets of typical shapes (cylinders, cones, hemispheres), ribbed panels and panels with cavities. Building of armoured and fireproof welded structures through a combined use of dissimilar materials and their joining methods, as well as compact transformable billets, which can be transformed into large-volume structures (tanks, compartments, habitable rooms, etc.). Manufacture of Thermal Protection Systems : Near- and trans-space structures require efficient thermal protection systems (TPS) to deal with reusable, multi-re-entry vehicles. The selection and combination of materials for maximum thermal, structural, and weight performance is crucial. The joining technology that is flying today is over thirty years old. Improvements in materials joining methods are enabling technologies for advanced flight concepts. Welding, brazing, soldering, adhesive bonding, and NDE are all pertinent to this field. Repair : Manufacture, repair, and overhaul continue to be a major driver of joining technology innovation in the aerospace industry. Repair technologies are driven by two competing factors; low metallurgical damage to the substrate and high deposition rates. These features, however, are generally mutually exclusive. This has driven technology innovations such as laser powder build- up, cold metal transfer and cold spray. There is also a push towards near net shape repair. This is attaching pre-formed repair elements, reducing the expense of post-deposition machining. Reducing material usage : Improving material buy-to-fly ratios, is a key element in reducing the overall costs of manufacture. To this end, welded components are increasingly replacing those machined out of single blocks of materials. Generally, two penalties are paid for replacing a fully machined component with a welded one. The first is loss of properties in the weld and heat affected areas. The second is geometric stability of the final part. New processes, better process control, better predictive capabilities, etc. will all be necessary to address this new generation of welded components. Implementation of low cost manufacturing technologies : Reducing the overall costs of manufacture continues to be a major driver for technology innovation in the aerospace industry. To this end, there is increasing interest in standardisation of parts, and subsequent increases in manufacturing volumes for those components. Higher volumes permit economies of scale. This has placed focus on higher productivity joining processes. Higher productivity joining ranges from increased deposition rates with existing processes, to the use of newer approaches. In this regard, laser processing, resistance welding, etc., with their inherent advantages in higher production volumes, will see increasing use in aerospace construction. Development of novel solid-state processes : Manufacturability of hardware through novel solid- state welding processes offers distinct advantages to the aerospace industry reducing buy-to-fly ratios and production costs. Ultrasonic additive manufacturing (UAM) is one such technology based on solid-state welding, joining successive layers of material to produce near net shape hardware. Producing hardware in this fashion requires minimal material consumption while producing highly accurate components. Fabrication of such hardware also allows for the development of smart

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Through Optimum Use and Innovation of Welding and Joining Technologies

Improving Global Quality of Life