Hardening

RAILWAY ALLIGATORS

Blast hardening of manganese steel rail cores (Hadfield type) is a technology used to increase the hardness of the surface and interior of the rail gator billet. This increase in hardness leads to an improvement in wear resistance and a reduction in core surface maintenance - grinding or welding. The surface hardness (tread) of a non-blast hardened core is in the range of around 200 HBW and the hardness decreases with depth in the material. The surface of the non-explosion hardened core wears down very quickly in the first few weeks that it is installed on the track, the wear is around 3 mm. Blast hardening of rail cores carried out before they are mounted on the track causes the hardness of the surface and lower layers to increase by up to 400 HBW or more. Blast hardening considerably increases the strength of the interior of the core to a depth of 30 mm or more. Metallurgical analysis of blast-hardened cores made from Hadfield or high manganese steel shows a martensitic transformation in the hardened areas. Casting defects such as microcracks and bubbles are automatically revealed after blasting, serving as an additional quality control.