RU2031749C1 - Method to produce hot rolled bars of commercially pure aluminum - Google Patents

Abstract

FIELD: metal hot processing. SUBSTANCE: method to produce hot rolled bars of commercially pure aluminum includes ingot heating, hot rolling in several passes and winding a coil with last pass rolling being occurred at 470 - 480 C at 100-120 c^-1 deformation rate and 50 - 70 per cent reduction. EFFECT: high quality of rolled metal. 1 tbl

Description

 The invention relates to the field of hot metal forming, mainly to hot rolling of strips of aluminum alloys.

 A known method of producing hot rolled strips of aluminum alloys [1], including heating ingots, hot rolling, winding into a roll and annealing rolls to obtain the required level of plastic properties of the strips. Annealing operation requires additional energy consumption, and also inhibits the performance of all rolling equipment.

The closest in its technological essence to the proposed is a method for hot-rolled sheets of aluminum and its low alloy [2], comprising heating of ingots, rough and finish hot rolling, coiling at heavy rolls at a temperature up to 330 ^{° C} and the strip speed to roll at this temperature. Long exposure of the strip at this temperature, occupying the annealing operation, ensures the course of the recrystallization process and obtain the required level of plastic properties.

 The disadvantage of this method is that the long exposure of the strip in a roll lengthens the process and inhibits the growth of productivity of all rolling equipment.

 The aim of the invention is to increase the productivity of the technological process for the production of hot-rolled strips of aluminum of technical purity by eliminating the operation of holding the strip in a roll while maintaining a given level of ductility of the strips.

The goal is achieved in that the method comprises heating the ingot to hot rolling in several passes, and coiling into a roll according to the invention in the last rolling pass is carried out at a temperature of ^about 470-480 C at the strain rate of 100-120 s ^-1 and a relative degree of compression of 50-70%.

The method is as follows. Ingots of technical grade aluminum are heated to the temperature of the onset of hot rolling, then rolled in a semi-continuous or reversible mill to a final thickness. Rolling in the final pass is carried out at a temperature of ^about 470-480 C at the strain rate of 100-120 s ^-1 and the relative reduction ratio of 50-70%, which allows the passage of the recrystallization immediately after hot deformation at the outlet from the stand. There is no need to hold the strip in a roll after hot rolling to achieve a softened state.

 The duration of heating aluminum ingots of technical grade is 3-6 hours for hot rolling of one ingot 0.05-0.1 hours, holding the strip in a roll after hot rolling for 48 hours. When eliminating the operation of holding the strip in a roll, the productivity of the rolling shop, taking into account the number of installed in it equipment increases by 10-15%.

 The table shows the degree of recrystallization of aluminum strips of technical purity at the exit from the stand, depending on the temperature-speed and deformation parameters of rolling in the last pass by the known and proposed methods.

From the table it follows that the strip rolled according to the claimed method, at the exit from the cage after the last pass is completely recrystallized (degree of recrystallization 100%). Increasing the technological parameters of rolling over the established limits (temperature 470-480 ^C, strain rate of 100-120 s ^-1, the relative reduction ratio of 50-70%) does not increase the softening bands (recrystallization rate 100%), and only causes an increase in power consumption. Therefore, the use of this area of technological parameters is not economically feasible.

PRI me R. Rolling strips of technical grade aluminum 4 × 1300 mm in size are carried out on a 2800 semi-continuous broadband mill. The rolling speed in the last stand of the continuous group is 3.3 m / s, in the last pass the strip is rolled from 7 to 4 mm. The temperature in the last deformation pass is 415 ^{° C,} strain rate - 45.3 cm ^-1, the relative reduction - 43%. The indicated temperature-speed and deformation parameters of rolling in the last pass provide 0% recrystallization (fully deformed state) at the exit from the stand, which makes it necessary to keep the strip in the roll at the temperature of the end of rolling in order to ensure the passage of recrystallization. To obtain a strip completely recrystallized at the exit from the last stand of a continuous group, the following rolling mode is prescribed. The strip in the last pass is rolled from 8 to 4 mm, the rolling speed is assigned 7.2 m / s. The temperature in the last deformation pass is 475 ^{° C,} strain rate - 100 s ^-1, the relative reduction - 50%. The degree of recrystallization of the strip at the exit of the stand after the last pass rolled according to the proposed mode is 100%. The need for long exposure of the strip in the roll disappears, the exclusion of which allows to increase the productivity of all rolling equipment.

Claims (1)

METHOD FOR PRODUCING HOT-ROLLED STRIPES FROM TECHNICAL ALUMINUM ALUMINUM, including ingot heating, hot laying in several passes and winding into a roll, characterized in that, in order to increase productivity while maintaining a given level of ductility of strips, rolling in the last pass is carried out at 470 - 480 ^o С with a strain rate of 100-120 s ^{- 1} and with a relative degree of compression of 50 - 70%.

Images