Method for improving structure uniformity of stainless steel extra-thick plate

Abstract

The invention relates to a method for improving the structure uniformity of a stainless steel extra-thick plate, in particular to a method for improving the microstructure uniformity of an austenitic stainless steel extra-thick plate, a billet is a forging plate blank formed by die casting, electroslag remelting and 3D forging, and the ratio of the billet thickness (H) to the finished plate thickness (h) is 4-5; the heating temperature of the billet is 1260-1300DEG C, and the heat preservation time is 0.5-0.8min / mm; dephosphorization is conducted through high-pressure water with a pressure of 20-25Mpa or above, the spraying time is within 2-5s, and the time for conveying the billet to a rolling mill after the billet is discharged from a furnace is 30-60s; the pass deformation rate of the first three passes is controlled to be 10-18%; when the thickness ranges from 200mm to 300mm, the pass deformation rate is controlled to range from 12% to 20%; when the thickness ranges from 60mm to 200mm, the pass deformation rate should be controlled to range from 20% to 30%; the heat preservation retention time of the billet is ensured to be 10-20 seconds between the passes; in the heat treatment process, the furnace temperature is controlled to be 200-400DEG C, the temperature rise speed of 400-700DEG C is 50-100DEG C / h, the temperature rise speed of 700DEG C to a target heating temperature is controlled to be 100-150DEG C, the heating temperature control range is 1000-1050DEG C, and the heat preservation time is 30-60min. The austenitic stainless steel extra-thick plate meets the requirements of key equipment of large engineering projects for the austenitic stainless steel extra-thick plate.

Description

technical field [0001] The invention relates to a method for improving the uniformity of the microstructure of an extra-thick stainless steel plate, in particular to a method for improving the uniformity of the microstructure of an extra-thick stainless steel plate. Background technique [0002] Due to its excellent mechanical, corrosion resistance, processing and welding properties, austenitic stainless steel has always played an important role in the development of all walks of life in society. With the advancement of human science and technology, more and more key equipment of large-scale engineering projects are gradually developing in large-scale and large-scale, and the demand for extra-thick austenitic stainless steel plates (thickness > 60mm) is gradually increasing. Since the uniformity of the microstructure has a great influence on the various properties of the material, users usually require the grain size rating range of the austenitic stainless steel plate to...

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Problems solved by technology

[0004] When rolling extra-thick plates, due to the limitation of the finished product weight and the size of the heating furnace, the thickness of the billet will increase accordingly, and the deformation and stress conduction conditions will become poor during thermal deformation. In addition, austenitic stainless steel is mainly composed of austenite grains. , it is impossible to refine the structure through phase transformation, and coarse grains are prone to appear in local areas, resulting in large differences in grain size and serious deterioration of microstructure uniformity, which is not conducive to the conventional mechanical properties and long-term properties of materials, and cannot meet the key requirements of large-scale engineering projects. Equipment usage requirements

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