Effective control method for pitted surface of plain carbon steel/Nb-containing steel plate of 20-30 mm thickness

Abstract

The invention discloses an effective control method for the pitted surface of a plain carbon steel / Nb-containing steel plate of 20-30 mm thickness. A steel plate billet is rolled into a finished plate of 20-30 mm thickness through the processes of heating, high-pressure water descaling, rough rolling, finish rolling, ACC laminar flow cooling, straightening, cooling, finishing and storage. The control method includes the steps that a three-stage heating mode of preheating, heating and uniform heating is adopted for the steel plate billet, the tapping temperature ranges from 1050 DEG C to 1135 DEG C as required, and high-pressure water descaling pressure ranges from 20 MPa to 23 MPa; two-stage controlled-rolling is adopted, rough rolling is conducted three to five times for descaling, finish rolling is conducted two to four times for descaling, and the finishing rolling temperature is controlled between 820 DEG C and 880 DEG C; an ACC laminar flow mode is adopted, and the finishing cooling temperature is controlled between 680 DEG C and 800 DEG C. A 250 mm*(1600 mm, 1800 mm and 2100 mm)*(2300-3300) mm blank is adopted for the steel plate billet. According to the control method, low-temperature heating and cooling after rolling are adopted; by means of process optimization, the occurrence probability of the pitted surface is lowered, the yield of plates of middle thicknesses is increased, production cost is reduced, and product profits are increased.

Description

technical field [0001] The invention relates to an effective control method for pitting of medium and thick plates, in particular to an effective control method for pitting of 20-30mm medium and thick plates of ordinary carbon steel / Nb-containing steel. Background technique [0002] The pitted surface of medium and heavy plates is one of the difficult surface quality problems faced by all iron and steel enterprises, and it is an important factor affecting the yield of medium and heavy plates. [0003] CN103831303A proposes a method for reducing pits on the surface of wide and thick plates, and solves the problem of pits on the surface of wide and thick plates from two aspects of heating and rolling processes. Similarly, CN101704026A also introduces a method for controlling pitting on the surface of a medium-thick steel plate, which optimizes all technological processes from the blank composition, heating and rolling processes. [0004] However, the problems in the above met...

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Problems solved by technology

[0004] But, the problem that said method exists is: CN103831303A and CN101704026A all adopt high-temperature heating, and tapping temperature is controlled between 1140-1245 ℃, and oxidation burning loss is more serious, and the iron oxide scale that produces is difficult to remove

CN103831303A defines the tapping temperature, descaling pressure, rolling pass, reduction rate and finish rolling temperature of rolling steel plates of different specifications, but does not define the cooling process; CN101704026A defines the casting billet composition, furnace temperature, The descaling pressure and the red return temperature of the final cooling are defined, but the rolling process is not defined