The 4th stage compressor IBR of the JSF F119 engine is fatigue limited. Surface enhancement, by the introduction of compressive residual stress, is a practical means of improving fatigue performance without changing material or design. Low Plasticity Burnishing (LPB) provides twice the HCF strength and four times the damage tolerance of shot peening in Ti-64 and IN718 laboratory specimens. LPB applied to the leading edge of the F404 Ti-64 1st stage fan blade has been shown to produce sufficient through-thickness compression for complete tolerance of 1.3 mm (0.050 in.) deep FOD. LPB offers rapid, affordable, surface enhancement using conventional CNC machine tools in a manufacturing environment. With the support of Pratt and Whitney, the feasibility of improving damage tolerance of the F119 4th stage compressor IBR blades with LPB processing will be investigated. LPB parameters and control software will be developed using existing tooling and 4-axis CNC facility. The HCF life and damage tolerance achievable with LPB will be documented and compared to the current practice of shot peening. Phase II will thoroughly document HCF performance of LPB processed blades, and address the development of an automated production facility for LPB processing full IBRs in manufacturing and repair. The immediate anticipated benefit of the proposed effort to the Air Force is elimination of the fatigue related performance limitations imposed on the F119 4th stage compressor IBR. Surface enhancement by LPB processing is expected to improve the 4th stage IBR blade HCF life and FOD tolerance sufficiently to allow engine operating restrictions to be relaxed. Long term benefits will be realized from expansion of LPB processing to improve damage tolerance of other IBRs, and as a post process following weld repair. Continuing benefits will be realized in both IBR performance and reduced maintenance and inspection costs. Commercialization will begin with production LPB processing of the F119 4th stage IBR, followed by transition of the technology to other military aviation applications. LPB is well positioned for commercialization due to the low costs of processing and capitalization relative to laser shock peening (LSP), and the improved depth and stability of the compressive layer produced by LPB relative to shot peening. LPB can be applied with conventional CNC machine tools, and can be easily incorporated into existing manufacturing operations. Surface Enhancement Technologies, LLC has been licensed and positioned to provide the LPB technology and support necessary for rapid effective transition into manufacturing. Demand for improved HCF performance and cost reduction from military owner-operators will lead to LPB processing of other critical rotating parts during manufacturing and overhaul. Aging aircraft applications to improve HCF, SCC and corrosion fatigue performance in aluminum airframe alloys and steels will follow. Military applications will be followed in the commercial aviation sector, driven by improved HCF performance and cost reduction. Potential secondary commercial opportunities for LPB to improve HCF and SCC performance in the aerospace, automotive, and power generation turbine industries are vast, and will follow the initial military applications over a period of several years.
