METHOD OF PIPE ROLLING MILL MANDREL HEAT TREATMENT Russian patent published in 2014 - IPC C21D9/28 C21D1/42 

FIELD: process engineering.

SUBSTANCE: invention relates to machine building. Mandrel 15 meters in length and 137-200 mm in diameter is made from alloyed tool steel that contains chromium in amount of over 4 wt %, every other carbide-forming element and silicon in amount of 1 wt % and carbon in amount of 0.44 wt %. It is subjected to quenching by induction heating at current frequency of 50-1000 Hz to 1040°C-1080°C, cooled by sprayer, tempered at 705°C-725°C and air cooled. Note here that mandrel is displaced in quenching at the rate of 70-180 mm/min while in tempering at 70-180 mm/min.

EFFECT: required distribution of physical and mechanical properties.

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