Date: Thursday, Jan 17th
Presenter: Prof. Bill Wood, Portland State University
Electrospark deposition, ESD, using Stellite 21 electrode followed by ultrasonic impact treatment, UIT, for residual stress modification and for enhancing the as deposited hardness, has been applied to an ultrahigh strength corrosion resistant precipitation hardened Custom 465 alloy and to quench and tempered ultrahigh strength low alloy steels at equivalent strength levels, greater than 200ksi (1,400MPa) yield strength. Heat affected zone widths were 8-15 microns and UIT treatment resulted in ESD and HAZ hardness levels equivalent to base properties. Fully reversed fatigue tests using tapered constant applied stress levels established fatigue lives ranging from about 100K to 20M cycle fatigue lives. Fatigue lives equivalent to base metal under high applied stress levels and 95% of base metal for 20M cycle lives were obtained.