A kind of manufacturing method of special thick plate

Abstract

The invention discloses a method for manufacturing an extra-thick plate (thickness>60mm), which belongs to the field of steel plate production in the metallurgical industry. The process steps are as follows: firstly, the slab heated to the temperature and descaled is transported to the cooling zone for forced cooling, the surface temperature is cooled to above the phase transition temperature Ar1 of the extra-thick plate material, and then the surface temperature rises to 780~ Between 880°C, send the billet to the rolling mill for rolling as soon as possible; when the surface temperature of the rolled billet is higher than 880°C, it needs to be forced to cool again before subsequent rolling. If necessary, the forced cooling-returning-rolling process can be repeated many times until the required thickness of the extra-heavy plate is rolled. This method can be used to increase the temperature difference between the surface layer and the central area to increase the strain in the central area, which is beneficial to refine the structure in the central area and improve the impact toughness; it is beneficial to eliminate the center porosity of the extra-thick plate; it can also reduce the thickness of the extra-thick plate. Side double. The manufacturing method of the extra-thick plate is low in investment and flexible in operation.

Description

technical field [0001] The invention belongs to the field of steel plate production in the metallurgical industry, and relates to a method for manufacturing an extra-thick plate with a thickness ≥ 60mm, aiming at solving the problem of low mechanical properties at the center of the rolled extra-thick plate, and the double-drum shape of the side of the steel plate during the rolling process. Edge folding problem caused by further rolling with double drum type. Background technique [0002] Under the requirements of large-scale and high-efficiency construction, a large single-weight, extra-wide, and extra-thick steel plate can reduce weld seams. In the construction of offshore platforms, high-strength and large-thickness steels are widely used, especially for structures such as lifting points, which require a thickness of 80mm; the steel used for racks in jack-up platform structures requires a yield strength level of 690MPa and a thickness of 80mm. 110~150mm. High-strength 4...

AI Technical Summary

Problems solved by technology

The remaining area in the thickness direction is not deformed, resulting in a "double drum" shape on the side of the rolled billet, such as Figure 2, if this shape is maintained until the finished product, it will reduce the yield of the blank

At the same time, the uneven deformation in the thickness direction will form compressive stress in the rolling direction in the hc thickness region of the surface layer, and tensile stress in the rolling direction will be generated in the middle, which will deteriorate the stress state in the middle

In some methods, the rolling of the vertical roller mill is used to partially eliminate the "double drum" shape, but the large width-thickness ratio of the extra-thick plate cannot be effectively improved without deformation or small deformation in the central area, so that the thermal deformation can improve the structure and performance. The effect is limited, so in the undeformed or small deformed central area, the deformation recrystallization, elimination of segregation, and reduction of porosity are far worse than those of the surface layer of the billet.

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