Method for controlling grain size of low-carbon austenitic stainless steel extra-thick plate

Abstract

The invention relates to a method for controlling the grain size of a low-carbon austenitic stainless steel extra-thick plate. The method comprises the following steps of that 1) a casting blank is heated, specifically, the casting blank with the thickness of 250 mm or below is fed into a stepping heating furnace for heating, after the casting blank is sequentially treated through a preheating zone, a heating zone and a soaking zone, and the casting blank is discharged out of the furnace; after high-pressure water descaling, the temperature difference between the surface of the casting blank and the center of the casting blank is controlled to be 10-15 DEG C; (3) the initial rolling temperature of rough rolling is greater than or equal to 1110 DEG C, and the surface is not descaled in the rough rolling stage; the finish rolling temperature in the rough rolling stage is greater than or equal to 1050 DEG C; after rough rolling is finished, the steel plate passes through 2-3 passes in an idle mode, and descaling water of a rolling mill is sprayed in each pass; the initial rolling temperature of finish rolling is greater than or equal to 980 DEG C, and the finish rolling temperature in the finish rolling stage is greater than or equal to 950 DEG and controlled cooling is carried out, specifically, the hot-rolled steel plate quickly passes through an ultra-fast cooling system after finish rolling. The method has the advantages that the problem that the surface grain size and the center grain size of the steel plate are inconsistent can be solved, and the grain size of the steel plate reaches level 3 or above.

Description

technical field [0001] The invention belongs to the technical field of austenitic stainless steel plate rolling, and relates to a method for controlling the grain size of a low-carbon austenitic stainless steel plate with a thickness of 40-80 mm. Background technique [0002] 304L stainless steel is a type of 304 series stainless steel with low carbon content. It has high high temperature strength, good corrosion resistance and low temperature toughness. It is widely used in various aspects of engineering construction, especially in the field of engineering applications. Low-temperature structural components that require impact toughness. However, in some special fields, for safety reasons, 304L austenitic stainless steel extra-heavy plates with high strength and thickness of 40-80mm are required. The uneven transmission of rolling force makes it difficult to achieve the uniformity of performance in the full thickness direction, such as improper process design and execution...

AI Technical Summary

Problems solved by technology

Studies have shown that when the rolling reduction ratio exceeds 6, the original microstructure of the billet has no obvious influence on the grain uniformity of the medium and thick plate; when the billet heating temperature and pass reduction are the same, the production process with a total reduction ratio of 6 can Steel plates with uniform grains throughout the thickness are rolled out; while optimization of other processes such as reduction rate does not significantly improve the uniformity of steel plate thickness, but increasing the compression ratio by increasing the thickness of the slab will lead to increased difficulty in the production of steel plates, and the production Significantly increased costs and lead times

[0006] Although the production methods disclosed in the above patents and documents have solved the problem of uneven grain size in the direction of the steel plate thickness, but their production process is complicated and the production cost is high, so it is not suitable for Mass production of low-carbon austenitic stainless steel extra-thick plates with low cost and uniform grain size throughout the thickness

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