METHOD OF THERMAL TREATMENT OF HIGH-STRENGTH LOW-CARBON STEEL Russian patent published in 2009 - IPC C21D8/04 C21D1/26 C21D9/46 

FIELD: process engineering.

SUBSTANCE: invention relates to production of rolled stock, particularly, to thermal treatment of coiled strip from high-strength low-carbon steel. Coiled strips are heated with standing at preset temperature and duration, followed by cooling and metal unsqueezing. Note here that to produce steel containing carbon of 0.03 to 0.05 wt % and with σ"в"=340 to 400 MPa, heating is carried out to 680°C, as per stand thermocouple, and with standing at said temperature to lagging point temperature of 660°C, volume of blowdown hydrogen making at least 2.8 "мУт" of metal. Note also that to produce steel containing 0.06 to 0.08 wt % of carbon with c σ"в"=380 to 440 MPa, heating is conducted till 680°C with interval of standing at said temperature equal to half the total time of metal standing and consequent cooling to 660°, as per stand thermocouple, and standing to lagging point temperature of 630°C. Note that water cooling in initiated, in both cases, at 280°C, while metal unsqueezing is conducted at lagging point temperature of 140°C.

EFFECT: higher quality of coiled strip.

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