UA81094C2 - Method of pouring of castings from steels of killed grades - Google Patents

Abstract

The invention relates to metallurgy and can be used at pouring of steels of killed grades into the casting molds. A method includes pouring killed steel in casting mold with top extension, in which the heat-insulating layer is located in the inter-wall space. Pouring is conducted at a temperature of heat-insulating layer, which is equal to 200-1250 DEGREE C, which reduces the heat emission from the ingot head.

Description

Description of the invention

The invention relates to metallurgy and can be used for pouring calm grades of steel in 2 castings.

There is a well-known method of pouring still steel, which uses a pouring vessel with an insulating insert.

The thickness of the insulating layer is 0.3-0.5 of the thickness of the wall of the mold |Grubyn K.G., Oiks G.N. Metallurgy of steel. M.: Metallurgy, 1970. p. 340-343). The disadvantages of this method include, firstly, the poor quality of the surface formed in the main part of the casting, due to the sticking of large exogenous inclusions in the cortical zone; 70 secondly - the depth of shrinkage defects remains quite large and reaches 12-1495 from the casting height.

There is a well-known method of pouring still steel, which uses a pouring vessel with a profitable extension.

A heat-insulating layer with a thickness of 0.3-0.7 of the thickness of the pouring wall is located in the inter-wall space of the inlet extension, and the thickness of the working wall of the extension is 0.1-0.4 of the thickness of the pouring wall t (patent of Ukraine Mo 77368). The disadvantage of this method is a rather large depth of shrinkage defects, and the obtained main cut within 11-12965 from the height of the casting.

The invention is based on the task of improving the method of pouring castings from stable grades of steel, in which, due to the increase in the temperature of the heat-insulating layer, it is possible to reduce the heat transfer from the liquid steel to the side walls of the mold in the main part of the molded casting by several times and thereby significantly reduce the length of shrinkage defects in the main part of the casting.

In the proposed method, which includes the pouring of still steel into a mold with a returnable extension, in which the heat-insulating layer is placed in the interwall space, pouring is additionally carried out at a temperature of the heat-insulating layer equal to 200-125020. In the proposed method, by reducing the heat sink in the main part of the molded casting from the side surfaces, conditions are created for moving the heat center of solidification to the end of the upper part (o) of the casting and reducing the volume and length of shrinkage defects. It is known that heat loss through the wall of the inlet extension is directly proportional to the temperature difference of the inner and outer surfaces of the wall of the inlet extension and the coefficient of thermal conductivity of the wall material. Reducing the difference in temperature between - 20 walls by extensions with a simultaneous increase in the coefficient of thermal conductivity of the material of the heat-insulating layer when it is heated, allows to reduce (22) the heat transfer from the main part of the casting in a certain temperature range. Heat loss through the wall is determined as o a-(H-6) mb, where d is heat loss through the wall of the mold, W/m; -

I - temperature of the wall at the border with liquid steel, C ("15002С); eh

Her" - the temperature of the outer wall, "С (in the prototype it is equal to 80-17092С, in the proposed method 200-125025);

Хх - coefficient of thermal conductivity of the heat-insulating layer, W/m C, for example: 7, - (0.312-0.477 Isr/ odo) - for "lightweight fireclay, (or - (N k B/2); 8 - thickness of the heat-insulating layer, m. Thus, in the proposed method, to a greater extent than in the prototype, in the main part of the molded casting, the volume of liquid steel is stored, which is used to feed shrinkage, which forms as a result of the crystallization of the metal.

If the temperature of the heat-insulating layer is less than 2002С, then almost the same conditions are created as in 745 without heating the heat-insulating insert, because in the conditions of current production, the molds are heated

Me to a temperature of 80-17026. - If the temperature of the heat-insulating layer is higher than 12509C, then the thermal conditions of operation of the riser attachment will lead to the grooving of its working walls, and the impossibility of removing the riser attachment from the casting. Problematic solidification of the main part of the casting for about 2-4 hours. (se) 50 The method is carried out as follows.

I» Casting of still steel is carried out in a mold with income extensions, in which a heat-insulating layer in the form of preheated fireclay powder is placed in the interwall space of the income extension.

After pouring, the metal in the mold hardens after a certain time. Next, the casting is stripped, the profit margins and castings are sent to the composition preparation shop. Fireclay powder is poured out of the inlets, heated again and poured into the interwall space of the inlets, after which

GF) put extensions on the mold and in the steelmaking shop they pour still steel into this form. With the reduction of heat transfer through the side surfaces of the main part of the casting, it is possible to reduce the length of shrinkage defects in the main part of the casting by several times, and, accordingly, to increase the yield of the suitable product in comparison with the prototype. because Example of a specific implementation.

In the conditions of the metallurgical plant, calm grades of steel are poured using the proposed method into deep-bottomed vats with profitable additions. Fireclay powder preheated to 8009С is fed from a special hopper into the interwall space of the inlet extension with a width of 125mm (0.576 when the thickness of the mold wall is 6-22Omm and the thickness of the working wall of the mold equal to 45mm - 0.25) in the composition preparation workshop to the upper end of the revenue extension. The height of the extension is 400 mm. After that, insulating inserts are placed on the molds prepared for pouring, and castings weighing 7.5 tons are sent for pouring. The pouring height is 2500 mm, including 300 mm in the revenue part. Pouring is carried out under slag. Upon completion of the filling of the profit margin, the lunkerite powder is poured onto the surface of the liquid metal.

After solidification, the castings are stripped, placed in heating wells and, after heating, rolled on a bloomer into a roll with a section of 280x260 mm and a length of 14 m. The main part with a length of 7000 mm (595 lengths) and the bottom part with a length of 100-150 mm (up to 1956 lengths) are cut with scissors. Next, the casting is transferred to the preparation stage 550, where a blank of 7 125 mm is obtained. The quality of the macrostructure in the blanks is satisfactory along the entire 7/0 length, there are no shrinkage defects (ultrasound control).

Claims (1)

The formula of the invention is the method of pouring castings from calm grades of steel, which includes the pouring of steel into a foundry with an add-on, in which the heat-insulating layer is placed in the inter-wall space of the add-on, which is distinguished by the fact that pouring is carried out at a temperature of the heat-insulating layer equal to 2000-1250 26. Official Bulletin "Industrial Property". Book 1 "Inventions, useful models, topographies of integrated microcircuits", 2007, M 19, 26.11.2007. State Department of Intellectual Property of the Ministry of Education and Science of Ukraine. 6) « (o) «c) «- d) - and? (ee) - («c) se) c» ime) 60 b5