Production method of low-alloy and high-strength thick plates

Abstract

The invention provides a production method of low-alloy and high-strength thick plates, and the production method comprises the following steps: after electric furnace smelting is performed, carrying out LF (Ladle Furnace) refining and VD (Vacuum Degassing), controlling the casting temperature and casting time of a body and a cap, after steel ingots are cooled, quickly demoulding the steel ingots, carrying out heat preservation on the cap by using a heat-holding cover, and cooling the steel ingots in a cooling device; putting the steel ingots into a furnace when the furnace temperature is 600-700 DEG C, after tightly covering the steel ingots for 5-8 hours, heating the steel ingots to 1150 DEG C at a speed of 40-60 DEG C / h and carrying out heat preservation on the steel ingots, and freely heating the steel ingots to1180-1220 DEG C 5 hours before rolling; carrying out axial rolling on the steel ingot firstly so as to eliminate tapers, wherein the starting rolling temperature is greater than 1150 DEG C, the finish rolling temperature is 850-950 DEG C, the total reduction rate is greater than 50%, the slow cooling stacking temperature is not less than 500 DEG C, and the slow cooling time is not less than 48 hours; carrying out normalizing treatment on rolled steel plates at a temperature of 880-920 DEG C, and carrying out heat preservation on the steel plates at a speed of 1.9-2.25 mm / min. The mechanical properties, especially Z-direction properties, of super-thick steel plates produced by using the method disclosed by the invention completely meet the requirements, the yield strength Rel of the steel plate is greater than or equal to 300 MPa, the percentage reduction of cross sectional area Z is greater than to equal to 50%, the qualified rate of flaw detection is over 90%, and the production cost of the steel plate is low.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and particularly relates to a production method for a 350-400mm low-alloy high-strength extra-thick steel plate with excellent Z-direction performance. Background technique [0002] In recent years, with the continuous increase of super high-rise and long-span steel structure construction projects, the demand for extra-thick steel plates in industries such as energy, transportation, construction, shipbuilding, and machinery manufacturing is increasing. The performance and thickness of extra-thick steel plates require also increased at the same time. At present, there are very few iron and steel enterprises that can produce extra-thick specifications with Z-direction performance, especially 350-400mm thick extra-thick steel plates, which cannot be produced due to reasons such as difficult production and special process equipment requirements. [0003] The so-called low-alloy high-strength thic...

AI Technical Summary

Problems solved by technology

[0004] Chinese patent application publication number CN102345049A provides "a kind of low-alloy Q345C-Z35 thick plate and its production method", which provides a low-alloy Q345C-Z35 thick plate without adding Nb and Ti microalloying elements, and ensures that the steel plate The performance of each item meets the requirements of the national standard, but the thickness is ≤80mm, which cannot meet the requirements of thicker steel plates

[0006] To sum up, at present, if all extra-thick steel plates can meet the Z-direction performance requirements, the thickness specification is thinner; if the thickness specification is larger, the Z-direction performance cannot meet the requirements, so it has to be at the cost of loss of production cost , to meet thickness and Z-direction performance requirements

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