D. A. Hartman, M. J. Cola, V. R. Dave, Beyond6 Sigma, Santa Fe, NM
Integrally Bladed Rotors – IBRs – are an important part of current and future military aeroengines. The use of IBR allows lower weight rotors with decreased drag and improved compressor efficiency. Repair of these parts however is currently problematic. The repair process selected must have the following attributes in order to be successful: i) it must not compromise the remaining life of the IBR; ii) it must be amenable to flexible operations that could be located globally; and iii) it must be cost-effective vs. the price of replacement. Arc welding technologies are very cost-effective and are amenable to automated robotic operations, but there are significant process control and weld quality challenges that are barriers to entry for such technologies.
In this work we show a path to develop and validate a prototype process for Titanium Gas Metal Arc Welding (GMAW) for IBR weld repair. Titanium GMAW is challenging on account of the tendency for the cathode spot to wander, thereby creating an arc instability that impacts the weld bead geometry as well as weld quality. Additionally, there are challenges in the synchronization of pulses in the power supply to assure good bead geometry as well as uniform material transfer. To overcome these challenges and to meet the stringent quality requirements for IBRs, a novel monitoring and control methodology known as In – Process quality Assurance – IPQA – is implemented to sense and control vital aspects of the welding process not possible with current approaches. Practical examples are shown and the progress towards a viable GMAW repair process is reviewed, including metallurgical and weld quality aspects, weld parameters and weld process stability, and the end-goal of integration of the technology into commercially available power supplies.
Summary: Integrally Bladed Rotors – IBRs – are an important part of modern military engine design as well as an emerging part of commercial engine design. the cost effective repair of IBRs is a currently a very critical need for technology development, hence this current effort. The repair process selected must have the following attributes in order to be successful:
1)It must not compromise the remaining life of the IBR
2)It must be amenable to flexible operations that could be located globally
3)It must be cost-effective vs. the price of replacement
This work shows significant progress towards Pulsed Gas Metal Arc Welding, or GMAW-P, in conjunction with In-Process Quality Assurance – IPQA – will result in a repair process for small-scale damage that may be capable of meeting these requirements.
