High Pressure Waterjets – An Innovative Means of Alpha Case Removal for Superplastically Formed Titanium Alloys

Abstract:

Ultra high-pressure waterjets (WJ) have gained consideration as a viable alternative to conventional material removal and cleaning methods such as chemical milling, grit blasting, and grinding. Waterjets have often been considered for the stripping of unwanted coatings, but they also exhibit an inherent ability for the controlled milling of metallic materials. The waterjet material removal process poses a secondary benefit – the material erosion occurs due to the repetitive impact of droplets within the waterjet stream, which also serve to induce compressive residual stresses in the shallow sub-surface layers of the work piece. An experimental study was conducted to explore the removal of the alpha case layer on Superplastically Formed conventional and fine grain Ti-6Al-4V specimens. The resulting surface roughness parameters and completeness of alpha layer removal were characterized. Based on the experimental results, waterjet removal processes may serve as an alternate method for the post-processing of Superplastically Formed titanium alloys.

• Periodical: Key Engineering Materials (Volume 433)
• Pages: 103-111
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.433.103
• Online since: March 2010
• Authors: A. Chillman, Mamidala Ramulu, M. Hashish, A. Cantrell
• Keywords: Alpha Case, Erosion, Removal, Super Plastic Forming (SPF), Titanium, Waterjet

References

[1] Barnes, A.J. Superplastic Forming 40 Years and Still Growing., Journal of Materials Engineering and Performance. Vol 16, pp.440-454. (2007).

DOI: 10.1007/s11665-007-9076-5

[2] Pitt, F. and Ramulu, M. Experimental Investigation of Superplastic Forming Conditions on the Oxygen Absorption in Titanium,. Transactions of NAMRI/SME. Vol. 34, 2006, pp.39-46.

[3] Pitt, F. and Ramulu, M. Influence of Grain Size and Microstructure on Oxidation Rates in Titanium Alloy Ti-6Al-4V Under Superplastic Forming Conditions., Journal of Materials Engineering and Performance. Vol 13, pp.727-734. (2004).

DOI: 10.1361/10599490421394

[4] Knapp, J.K. and Taylor, T.A. Waterjet roughened surface analysis and bond strength., Surface and Coating Technology, Vol. 86-87, pp.22-27, (1996).

DOI: 10.1016/s0257-8972(96)02995-7

[5] Louis, H., Polak, H., Pude, F., and Schenk, A. Pure WJ Cleaning Process Characterization: Approach and Technologies., 6th International Conference of Management of Innovative Technologies. MIT, (2003).

[6] Chillman, A., Ramulu, M., and Hashish, M. Investigations of Surface Preparation in Superplastic Formed Metals., Proceedings of the 2007 WJTA Conference and Expo. August, 19-21, 2007. Houston, TX.

[7] Chillman, A., Ramulu, M. and Hashish, M. Waterjet Peening and Surface Preparation at 600 MPa: A Preliminary Experimental Study., ASME Journal of Fluids Engineering, Vol. 129, pp.485-490, (2007).

DOI: 10.1115/1.2436580

[8] Hashish, M., et al, "Method and Apparatus for Fluidjet Formation, US patent number 6280302, August (2001).

[9] Kunaporn, S. and Ramulu, M. Ultra High Pressure Waterjet Peening, Part I: Surface Texture., Proceedings of the WJTA American Waterjet Conference: Volume 1, 2001, pp.90-95.

[10] Kunaporn, S., Chillman A., Ramulu, M., and Hashish, M. Effect of waterjet formation on surface preparation and profiling of aluminum alloy., Wear. Vol. 265, pp.176-185, (2008).

DOI: 10.1016/j.wear.2007.09.008

[11] Momber, A.W. Concrete failure due to air-water jet impingement., Journal of Materials Science, Vol. 35, pp.2785-2789, (2000).