Method for improving internal quality of steel plate

Abstract

The invention discloses a method for improving the internal quality of a steel plate, which comprises the following steps that: (1) covering agents in big and intermediate bags are baked before an LF furnace smelts, so the water contents of the covering agents in big and intermediate bags are reduced to be lower than 0.5%; (2) after a slab is cut, stacking for slow-cooling is carried out, wherein the temperature of the stacking for slow-cooling is 800-950 DEG C, the time of the stacking for slow-cooling is more than 48h, so the hydrogen content in a casting blank is lower than 3PPm; and (3) the finished steel plate with the thickness of 18-70mm is air-cooled to 260-500 DEG C, stacking for slow-cooling is quickly carried out on the steel plate in a cooling bed area, when the temperature of the stacking for slow-cooling is 260-500 DEG C, the stacking number of the steel plates is not less than 8, the time of the stacking for slow-cooling on the steel plate with the thickness of 30-70mm is longer than 48h, the time of the stacking for slow-cooling on the steel plate with the thickness of 18-30mm is longer than 24h, so the hydrogen content of the finished steel plate is smaller than 1PPm. Under the conditions of no RH or VD vacuum treatment equipment, special hydrogen diffusion equipment and the like or not using the vacuum treatment equipment for reducing the cost, through reducing the hydrogen content in the steel, the crack which is caused by the hydrogen in the center of the steel plate is prevented from being produced, and the flaw detection acceptability of the steel plate is improved.

Description

technical field [0001] The invention relates to a method for improving the internal quality of a steel plate. Background technique [0002] Containers, bridges, boilers, pipeline steel, building structural steel and other hot-rolled steel plates require ultrasonic flaw detection in addition to meeting the requirements of size specifications, mechanical properties, and surface quality to ensure the safety and reliability of the project. However, due to its poor internal quality and low pass rate of flaw detection, it seriously affects the production cycle and increases production costs. Factors affecting the internal quality of the steel plate include high hydrogen content and severe segregation. After a large number of comparative tests, inspections and analyzes of different steel types, it is concluded that hydrogen-induced cracks in the core of the steel plate are the main reason for the poor internal quality of the steel plate. [0003] During the smelting and pouring pr...

AI Technical Summary

Problems solved by technology

Under the interaction of hydrogen pressure and internal stress, the strength limit of the metal is exceeded, resulting in cracks in the core, which eventually lead to the failure of ultrasonic flaw detection