The effect of ion implantation on the fatigue life and corrosion resistance of M50 steel bearings

With the overall objective to improve the service life and reliability of gas turbine engine bearings by increasing their corrosion resistance, a collaborative project under the EEC BRITE/EURAM programme was initiated. The project was aimed at developing an ion implantation technique to implant bearing components with metallic species and to optimize the process to improve the service life of bearings in situations in which salt water contamination of the lubrication oil might occur. As part of the programme of work, testing was carried out to assess the effect of chromium implantation on the rolling contact fatigue (r.c.f.) life of bearings, made in M50 aero bearing steel, operating under conditions similar to those experienced by gas turbine engine main shaft bearings during aircraft take-off. Implantation of chromium did not adversely affect the r.c.f, life of bearings made in M50 material. Following testing, non-implanted and chromium-implanted bearing components were corrosion tested to determine whether the improvement in corrosion resistance of M50 material, produced by implantation with chromium, was maintained after the bearing had been run. The improvement in the corrosion resistance of MS0 material achieved by implantation with chromium was maintained after the bearings had been run for 1000 h.