METHOD OF HEAT TREATMENT OF SOLID-ROLLED RAILROAD WHEELS FROM ALLOYED STEEL Russian patent published in 2017 - IPC C21D9/34 C22C38/28 C22C38/26 

FIELD: metallurgy.

SUBSTANCE: method includes heating to the austenitizing temperature, holding at this temperature, intermittent hardening of the rim with water, subsequent cooling of the wheels and drawing-back. Wheels are made of steel containing the following components, wt %: carbon 0.46-0.54, silicon 0.25-0.45, manganese 0.85-1.2, chromium 0.80-1.10, niobium 0.01-0.05, vanadium 0.08-0.20, molybdenum not more than 0.05, titanium not more than 0.01, phosphorus not more than 0.030, sulfur no more than 0.020, nickel and copper not more than 0.25 each, the rest is iron and unavoidable impurities, including hydrogen no more than 0.0002. Hardening of the rim with water is carried out by three-way cooling it from the spraying devices for 290-330 seconds, while the water pressure in the spraying devices is being increased from zero to 0.07-0.09 MPa during 75-85 seconds with further cooling at constant pressure up to formation of martensitic-bainitic-troostite structure in the rim at the depth of the working layer to 30 mm. Subsequent cooling of the wheels is carried out in the air until a ferrite-pearlite structure forming in the disk and hub, and drawing-back is carried out at a temperature of 500-550°C for at least 2 hours.

EFFECT: increased level of the rim strength characteristics, wear resistance, limit of contact fatigue endurance, the required level of plastic and viscous characteristics of the wheel metal is provided.

2 cl, 1 dwg, 6 tbl