Method for restraining macrosegregation of large steel ingot
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A technology of macro segregation and steel ingots, which is applied in the field of casting of large steel ingots, can solve the problems that the macro segregation of large steel ingots has not been effectively solved, the application is difficult, and cold shut defects, etc. Improved effect
Inactive Publication Date: 2015-03-25
TSINGHUA UNIV
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Problems solved by technology
Relevant documents and patents (CN101508018) believe that the macro-segregation of large steel ingots can be effectively suppressed by controlling the parameters of the multi-clad co-casting process. However, there are many problems in the actual engineering application process: 1) The last ladle of molten steel adopted by this technology is delayed Pouring technology is the key to solving the macro-segregation of large steel ingots. However, due to the use of sealed vacuum casting technology on site, it is extremely inconvenient to delay pouring for a long time, so this technology is difficult to apply on site because; 2) This technology is used in The steel ingot has been solidified for a long time before pouring the last ladle. When the last ladle of molten steel is poured on the solidified skin, internal cold-shock defects will occur, so this technology may cause other internal defects in the ingot
Although many scholars and researchers have made some progress in the study of macro-segregation of large steel ingots, the problem of macro-segregation of large steel ingots has not been effectively resolved.
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Embodiment 1
[0032] In this embodiment, the material of the ingot mold is gray cast iron HT250, the preheating temperature of the ingot mold is 100°C, a heating riser is used, the taper of the heating riser is 10%, the height-diameter ratio of the steel ingot is 1.2, and the total weight of the steel ingot is 1.2. It is 438 tons, and the pouring temperature is 1560 ℃.
[0033] Process 1: 1) Using three packs of continuous vacuum casting; 2) Using heating risers, the heating temperature is 1530 ℃ (higher than the liquidus temperature), the heating time of heating risers is 10 hours, and covering agent and heating agent are used at the same time 3) The carbon content of the first ladle of molten steel is 0.51%, the carbon content of the second ladle of molten steel is 0.45%, the carbon content of the third ladle of molten steel is 0.37%, and the continuous pouring time is 5200 seconds; Both weigh 150 tons.
[0034] Process two: steps 1), 3) and 4) are exactly the same as process one, but th...
Embodiment 2
[0039] Compared with Example 1, the heating process of the 438-ton steel ingot is the same in this implementation, but the composition of the last ladle of molten steel in the continuous vacuum casting process of multi-cladding is different.
[0040] Process five: 1) Using three-pack continuous vacuum casting; 2) Using a heating riser, the heating temperature is 1530 ℃ (higher than the liquidus temperature), the heating time of the heating riser is 30 hours, and a covering agent and a heating agent are used at the same time. 3) The carbon content of the first ladle of molten steel is 0.51%, the carbon content of the second ladle of molten steel is 0.45%, the carbon content of the third ladle of molten steel is 0.37%, and the continuous pouring time is 5200 seconds; Both weigh 150 tons.
[0041] Process six: steps 1), 2) and 4) are exactly the same as process five, but the carbon content of the third ladle of molten steel in step 3) is 0.30%.
[0042] Process seven: Steps 1), ...
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Abstract
The invention relates to a method for restraining macrosegregation of a large steel ingot. The method for restraining macrosegregation of the large steel ingot comprises the following steps that (1) a steel ingot mould is placed in a vacuum tank and is located on a base plate, and an exothermic riser is arranged on the inner side of a steel ingot mould riser; (2) the steel ingot mould is preheated, wherein the preheating temperature ranges from 100 DEG C to 200 DEG C; (3) after the steel ingot mould reaches the preheating temperature, steel ingot pouring is conducted according to the multi-ladle continuous vacuum pouring technology, the time interval between every two adjacent ladles is zero second, molten steel in the first ladle is high in carbon content, and the carbon contents of molten steel in other ladles become lower in sequence, so that a normal segregation area at the position of the large steel ingot riser is restrained; (4) when pouring of molten steel is completed, the vacuum tank is opened, and an exothermal agent and a heat preservation and covering agent are placed in the exothermic riser in the top of the steel ingot; (5) the exothermic riser is started for heating after the exothermal agent and the heat preservation and covering agent are added till the steel ingot is solidified completely and demolding is conducted. According to the method for restraining macrosegregation of the large steel ingot, macrosegregation of the large steel ingot can be reduced, tissue is improved, primary shrinkage of the riser is reduced greatly, and the method is suitable for production of large steel ingots made of various materials.
Description
technical field [0001] The invention relates to a casting method for large-scale steel ingots, in particular to a continuous vacuum casting process in which a traditional large-scale thermal insulation riser is designed as a heat-generating riser and simultaneously multi-cladding is used to suppress macrosegregation of large-scale steel ingots. Background technique [0002] The production of high-quality large steel ingots is an important issue facing the development of my country's equipment manufacturing industry. At present, super-large-scale is an important trend in the development of equipment manufacturing technology in the world. This trend places new and higher demands on the production of large ingots. Taking the new generation of million-kilowatt nuclear power equipment as an example, key components with high technical requirements, large specifications and complex shapes, such as the overall top cover, nozzle section, lower head and conventional island low pressu...
Claims
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Application Information
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