The effect of ion implantation on the lifetime of punches

In order to increase the lifetime of punches, made of Vasco Wear steel, implantations with C, N, B, Ti and co-implantation with Ti and C were performed at energies from 50 keV to 200 keV and 600 keV and 700 keV with different doses in the range of several times 10high18 cmhighminus2, measured perpenducular to the ion beam. A maximum increase of lifetime by a factor of 3.6 was reached. The surface roughness had a large influence on the increase of lifetime and the improvement caused by a specific ion species. The maximum improvement was obtained for the lowest surface roughness (Rsuba is equal to 0.04 Mym). Therefore, when performing the implants, punches with low surface roughness should be used. The most successful ion species were boron and nitrogen for the lowest surface roughness used (Rsuba is equal to 0.04 Mym), and after changing the polishing procedure (Rsuba is equal to 0.14 Mym) titanium and nitrogen at medium energies (100 keV to 200 keV). High energy implantation (700 keV) resulted in an increase of a factor of 2.1 at lower doses (5.6 x 10high17 cmhighminus2), but is uneconomical due to low current density. In laboratory wear tests (ball on disk) no improvement by ion implantation could be found. These results prove that it is difficult to compare field tests and laboratory tests because of different testing conditions.