Friction and Wear Reduction of 440C Stainless Steel by Ion Implantation
- PDF / 1,069,107 Bytes
- 6 Pages / 417.6 x 639 pts Page_size
- 0 Downloads / 194 Views
FRICTION AND WEAR REDUCTION OF 440C STAINLESS STEEL BY ION IMPLANTATION*
L. E. POPE,* F. G. YOST, D. M. FOLLSTAEDT. S.T. PICRAUX and J. A. KNAPP *Sandia National Laboratories, P. 0. Box 5800, Albuquerque, New Mexico 87185 U.S.A.
ABSTRACT Friction and wear tests on ion-implanted 440C stainless steel discs have been extended to high Hertzian stresses (< 3150 MPa). Implantation 2of 2 2 x 1015 Ti/mm (180-90 keV) and 2 x 1015 C/mm (30 keV) into 440C reduces friction (-40%) and wear (> 80%) for Hertzian stresses as large as 2900 MPa, stresses which significantly exceed the yield strength of 440C (-1840 MPa). Implantation 15 2 of 4 x 10 N/mm (50 keV) into 440C reduces friction slightly (-25%) for Hertzian stresses < 1840 MPa but provides little or no reduction in wear. The amount of Ti remaining in the wear tracks correlates with the reductions in friction and wear. The implantation of Ti and C produces an amorphous surface layer which is believed to reduce friction and wear, whereas N implantation is expected to produce hard nitride particles which probably do not modify the hardness of 440C (KHN = 789) significantly.
INTRODUCTION Surface modification by ion implantation has been found in recent years to reduce friction and wear of metal surfaces [1-2]. For unlubricated wear couples, beneficial results have been obtained consistently for the implantation of Ti and C into steel surfaces [3-7]. The addition of Ti and C reduced friction coefficients by -50% and decreased wear by up to -85%. In contrast, beneficial results for unlubricated wear couples have not been found consistently for N implantation into steels. Reduced wear seems to be limited to tests with short sliding distances, low loads or abrasive wear by diamond particles for 304 and 15-5 PH stainless steels [8-10]. N implantation into 52100 steel did not always reduce wear [2,6]. Implantation of N into 304, 15-5 PH and 52100 steels did not reduce friction coefficients [4,9]. Our earlier studies have shown that the implantation of Ti and C into 440C stainless steel reduced friction and wear [3]; however, the lighter loads used previously produced relatively shallow wear depths and less easily discernable reductions in wear due to implantation. The effect of N implantation into 440C has not been reported. Presented here are the unlubricated pin-on-disc wear results on 440C after Ti and C implantation and after N implantation. Hertzian stresses up to 1.75 times the bulk yield strength are evaluated. Wear tracks are analyzed to determine wear mechanisms and the role of the implanted surface alloy in friction and wear reduction.
*This work was supported by the U. S. Contract Number DE-AC04-76-DP00789. Mat.
Res. Soc. Symp.
Proc. Vol.
Department of Energy (DOE)
27 (1984)@EIaevier Science Publishing Co., Inc.
under
662
EXPERIMENTAL PROCEDURE The 440C discs were prepared and heat treated to maximum hardness (KHN = 789) with a bulk yield strength of -1840 NPa as discussed previously [3]. One group remained unimplanted for reference. A second group was 2 implan
Data Loading...
