爆発硬化した高マンガンオーステナイト鋳鋼の耐摩耗特性

抄録

Explosion hardened high manganese austenitic cast steel is being tried for rail crossing recently. In this study, in order to clarify the wear characteristics of explosion hardened high manganese cast steel, the wear tests by an Amusler type testing machine were performed under the unlubricated conditions of rolling and sliding-rolling contacts. Furthermore, the behavior of deformation of small testing blocks due to repeated impacts by the dropping hammer method was examined and compared with that of the original steel.
The results obtained are summarized as follows:
(1) Under the rolling contact the wear resistance of explosion hardened steel was far superior to the original steel, but under the sliding-rolling contact it made little difference. In the explosion hardened steel containing the defects caused by explosion working or casting, the wear was greatly accelerated.
(2) The feature of wearing surface of carbon steel tyre was a flaky spalling produced parallel to plastic flow, and that of high manganese cast steel was a fine uneven pitting irrespective of whether it was hardened by explosion working or not. It was supposed that the difference mentioned above is caused by the materials of wearing surface layers.
(3) The wear fragment of sliding-rolling contact consisted of the flake of carbon steel having the microcracks caused by slip and many fine fragments of manganese steel transferred to the former.
(4) The amount of compressive deformation of explosion hardened steel due to repeated impacts was smaller than that of the original steel. It seems that the wear resistance of explosion hardened rail crossing is attributable to this characteristic as well as the wear resistance of explosion hardened layer.