Method of making a hypereutectoid, head-hardened steel rail
US8241442B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 4, 2010 |
| Grant date | Aug 14, 2012 |
| Priority date | — |
| Expiry date | Nov 20, 2030 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC22C38/14
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A method of making a hypereutectoid, head-hardened steel rail is provided that includes a step of head hardening a steel rail having a composition containing 0.86-1.00 wt % carbon, 0.40-0.75 wt % manganese, 0.40-1.00 wt % silicon, 0.05-0.15 wt % vanadium, 0.015-0.030 wt % titanium, and sufficient nitrogen to react with the titanium to form titanium nitride. Head hardening is conducted at a cooling rate that, if plotted on a graph with xy-coordinates with the x-axis representing cooling time in seconds, and the y-axis representing temperature in Celsius of the surface of the head of the steel rail, is maintained in a region between an upper cooling rate boundary plot defined by an upper line connecting xy-coordinates (0 s, 775° C.), (20 s, 670° C.), and (110 s, 550° C.) and a lower cooling rate boundary plot defined by a lower line connecting xy-coordinates (0 s, 750° C.), (20 s, 610° C.), and (110 s, 500° C.).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.