SURFACE MODIFICATION OF AISI-4620 STEEL WITH INTENSE PULSED ION-BEAMS

A 300 keV, 30 kA, 1 mu s intense beam of carbon, oxygen, and hydrogen ions is used for the surface treatment of AISI-4620 steel coupons, a c ommon material used in automotive gear applications. The beam is extra cted from a magnetically-insulated vacuum diode and deposited into the top 1 mu m of the target surface. The beam-solid interaction causes a rapid melt and resolidification with heating and cooling rates of up to 10(10) K/s. Treated surfaces are smoothed over 1 mu m-scale lengths , but are accompanied by 1 mu m-diameter craters and larger-scale roug hening over greater than or equal to 10 mu m, depending on beam fluenc e and number of pulses. Treated surfaces are up to 1.8 x harder with n o discernible change in modulus over depths of 1 mu m or more. Qualita tive improvements in the wear morphology of treated surfaces are repor ted.