Heating-processing technology for improving mechanical property of high-intensity extra-thick plate

Abstract

The invention provides a heating-processing technology for improving the mechanical property of a high-intensity extra-thick plate, and the heating-processing technology can be used for improving the mechanical property of a normalizing high-intensity extra-thick plate and improving the normalizing qualification rate of the extra-thick plate. A water-cooling working procedure is added in the normalizing process of the extra-thick plate and is used for replacing air cooling for normalizing; the normalizing cooling speed is quickened, the phase-transition temperature of a steel plate is lowered, and the growth of microalloy element carbonitride can be inhibited, so that a small quantity of ferrite and a large quantity of thinner perlite structure can be obtained, and intensity, plasticity, low temperature brittleness and the like can be improved so as to guarantee the intensity of the steel plate and improve the qualification rate of the steel plate.

Description

technical field [0001] The invention belongs to the technical field of extra-thick steel plate manufacturing, and in particular relates to a heat treatment process for improving the mechanical properties of high-strength extra-thick plate. Background technique [0002] Micro-alloyed extra-thick steel is mainly used in bridges, boilers, pressure vessels, ships and other fields. The structure obtained during controlled rolling and controlled cooling of steel plates is usually not uniform, which affects the use of materials, especially thick gauge steel plates. Controlled rolling extra-thick steel plate adopts microalloying, which can effectively improve the strength and toughness of the steel plate, and improve the mechanical properties, but the plate thickness effect is serious. Therefore, normalizing heat treatment is required for thicker steel plates to obtain the best overall performance. Although normalizing can make the steel plate have good toughness, it will reduce i...

AI Technical Summary

Problems solved by technology

Although normalizing can make the steel plate have good toughness, it will reduce its strength. While normalizing improves the process performance of hot-rolled plate, it generally reduces the yield strength and tensile strength by 20-50MPa. It can be reduced by 80-120MPa. The main reason for the decrease in the strength of the steel plate after normalizing is that after re-austenitization during normalizing, the dislocation density inside the grain is greatly reduced, and the strengthening effect caused by grain refinement cannot Dislocation strengthening that fully compensates for losses

Conventional high-strength extra-thick plates are usually cooled by air cooling after normalizing, which leads to a high phase transition temperature of the steel plate, coarse ferrite grains, and a large decrease in the strength of the steel plate. If the carbon equivalent is increased, the welding adaptability will be caused. become worse, or even fail to meet the requirements of the delivery standard, resulting in unqualified products, which will cause a large number of steel plates to be downgraded or scrapped, resulting in economic losses and waste of resources

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