METHOD FOR HEAT TREATMENT OF LARGE-SIZED CAST PARTS OF FREIGHT CAR TRUCKS Russian patent published in 2017 - IPC C21D1/56 B61F5/00 C21D1/78 

FIELD: metallurgy.

SUBSTANCE: part of steel 20GL is heated to temperature not exceeding Ac₃+150°C, with holding for 30 -120 min, then moving it in protective casing into tempering device for not more than 5 min. Cooling in quenching device is carried out by fast-moving flow of cooling liquid under pressure of 1-5 atm for 2-20 min into two phases, first the part is cooled uniformly with 3-10 m³ of water during 5 -10 sec, and then 9-30 m³ of water with cooling of high-duty areas of the part with volume of water 10 -50% higher than said volume. The high-duty areas of the part are the areas that most frequently subject to damage during operation under the action of fatigue loads. As for side frames of freight car trucks, such areas are axle openings, especially the areas of the inner and outer radius R55.

EFFECT: improvement of part fatigue strength and resistance to destruction under cyclic loading.

4 cl, 3 dwg, 2 tbl