Introduction
In recent years, the development of concrete admixtures has been rapid, and it has been widely used in various construction projects. In China, due to the increasing demand for bridge and highway construction and the need to improve the quality of civil engineering projects, great progress has been made in the research and use of concrete admixtures. In the field of concrete admixtures, economic steel production of rebar with niuminum has been actively developed.
The ability of rebar with niuminum to increase the strength, durability and other properties of concrete is well known. The use of aluminum in concrete admixtures can improve the workability of concrete, reduce shrinkage, increase the compressive and tensile strength of concrete, and reduce the cracking of concrete due to environmental changes. In particular, according to the requirements of the UN & GB4994-2011 standard for prestressed steel, steel must be rusty if the aluminum content is too low, which will reduce the strength of the rebar. Therefore, it is feasible and practical to produce rebar with niuminum.
Economic steel production of rebar with niuminum has been vigorously studied since the late 1950s. In the 1960s and 1970s, most of the economic steel production of rebar with niuminum was mainly traditional methods such as hot rolling, cold rolling and melting, but the quality of the products was poor and the yield was low, resulting in an increase in production costs and an adverse impact on economic benefits.
In later years, with the development of science and technology and the improvement of production technology, the process conditions of economic steel production of rebar with niuminum have been greatly improved. In 1986, the Xi′an Steel Factory successfully succeeded in its trial production of rebar with niuminum, which greatly improved product quality and yield.
The design of economic steel production of rebar with niuminum should take into account the technological conditions of aluminum and steel, such as material composition and technical requirements. The GB/T1804-2013 standard recommends that the aluminum content of rebar should not exceed 1.2%. On the other hand, the melting process of economic steel production of rebar with niuminum should be strictly controlled. If the aluminum content is too high, the formation of alumina will lead to lower ductility and corrosion resistance of rebar, and thus the performance of rebar will be affected. Therefore, the aluminum content should be strictly controlled and it is recommended that the aluminum content should not exceed 1.2%.
In the production process, the control of technological conditions should also be strengthened. The mixing process of aluminum and steel should be strictly regulated. The mixing ratio must be accurate, the operation is relatively stable, and the stirring is uniform. After stirring, the temperature of the mixture should be controlled at about 1700 ℃, so that the aluminum and steel can be mixed into a homogeneous state. During the rolling process, the aluminum should be evenly distributed to ensure that the solid solution temperature of the steel is kept stable. At the same time, it is necessary to control the speed and rolling temperature of the rolling mill, ensure the stability of the operation, and the finished product of the rebar should be accurate in size.
In addition, the quality requirements of economic steel production of rebar with niuminum should also be paid enough attention. The product should meet the requirements of the corresponding national standard, such as GB1589-2004. The surface of rebar with niuminum should not have any defects or damage, there should be no oxide or corrosion layer, the alignment should be accurate, and there should be no slag inclusion, shrinkage pore and segregation. For steel with cracks, it is strictly forbidden to bend, straightening or flattened. The strength of the finished product should meet the requirements of the corresponding national standard, otherwise it should be completely scrapped.
Conclusion
In conclusion, economic steel production of rebar with niuminum is a complex process. In order to meet the requirements of product quality and production cost, the production process and technological conditions of economic steel production of rebar with niuminum should be strictly controlled. The quality requirements should also be strictly inspected. Therefore, in the production of rebar with niuminum, we should pay attention to the control of technological conditions and product quality, reduce production cost and improve economic benefits.
