抄録
In this study, case-hardened steel rollers with an effective case-hardened depth of 2 mm were fatigue-tested using a roller testing machine in order to elucidate their rolling contact fatigue life. They were made of three kinds of steels. These experimental results were compared with the results of the case-hardened steel roller with an effective case-hardened depth of 0.7 mm. The surface properties of all the test rollers were almost the same. The failure mode of all the test rollers was pitting due to surface cracking. The fatigue life and the surface durability of the rollers with an effective case-hardened depth of 2 mm were improved by the toughness effect due to nickel and the reduction of sulfur content in this experimental range. On the other hand, those with an effective case-hardened depth of 2 mm were far superior to those with an effective case-hardened depth of 0.7 mm. It was confirmed that the surface durability of the case-hardened steel rollers increased as their effective case-hardened depth increased under the same surface hardness.
