PROCEDURE FOR STRENGHENING RAILROAD WHEELS AND RAILROAD WHEEL WITH STRENGTHENED WORKING SURFACE Russian patent published in 2011 - IPC C21D9/34 C21D1/09 

FIELD: machine building.

SUBSTANCE: metal surface strengthening is carried out by means of low temperature plasma arc of direct action. As plasma generating gas there is used argon, mixture of argon with helium, and mixture of argon with carbon containing gases. Also, heating is performed with magnetic oscillation of arc with triangle shape of voltage pulse, scanning amplitude 20-45 mm and distance of treatment 10-30 mm. A strengthened surface layer consists of several sub-layers: at depth of 0.2-0.8 mm - structure of martensite with inclusions of upper bainite, - from 0.8 to 1.8 mm - trosto-martensite structure, - from 1.8 to 2.5 mm - sorbitic-martensite structure, - from 2.5 to 3 mm - sorbite, - over 3 mm - ferrite-pearlite structure of basic metal.

EFFECT: raised efficiency of strengthening process, 3 times increased wear resistance of strengthened working zone of wheel, 3 times reduced probability of development of hydrogen metal brittleness and tendency to brittle fracture.

2 cl, 1 tbl