High conductivity aluminum conductor rail

environment protection Aluminum alloy can obtain good mechanical properties, physical properties and corrosion resistance by heat treatment. aluminium Subway is becoming more and more popular because of its advantages of large traffic volume, high speed, no pollution, punctuality, convenience and comfort. In megacities or big cities, the construction of rail transit network is the best measure to solve the problems of large population concentration and traffic congestion in the city center. Metro operation is generally double line operation, and metro lines also need to build extension lines, parking lines, maintenance lines, etc. based on this, it is estimated that the total length of metro lines will need at least 1500km. aluminium In addition to the fishplate, pressing plate, terminal and other materials required for the installation of conductor rail, the total demand is at least 200000 tons. It can be imagined that Chalco aluminum complies with the market development and conducts project research on conductor rail profile, which solves the problem of large demand of conductor rail profile while ensuring strength performance and conductivity, Now the high conductivity aluminum conductor rail products have been mass produced, and have been highly praised by customers.

1.Technical difficulties of high conductivity aluminum conductor rail profile:

Due to its important power supply function, the conductor rail profile has special requirements for its mechanical properties and conductivity, which are higher than ordinary materials. The mechanical properties and conductivity are two mutual restricting factors, which bring the following two difficulties to the research and development of conductor rail profile.

Difficulty 2: the conductor rail profile is generally 6063-T6, and its mechanical property requirements are: tensile strength 215mpa, specified plastic extension strength 170Mpa, and elongation after fracture 8%. aluminium It can be seen that the tensile strength of the conductor rail profile is increased by 20 MPa, and the plastic extension strength is increased by 10 MPa. At the same time, the wall thickness of the conductor rail profile is relatively thick, which makes the production of the conductor rail profile more difficult to ensure its overall mechanical properties.

2.Affect high conductivity aluminum conductor rail analysis of conductivity factor and optimization of chemical composition

aluminium However, according to the theory of metal conductivity, the conductivity of metal is particularly sensitive to the solid solution atoms of impurities, and all the added elements will reduce the conductivity of pure aluminum. Therefore, controlling the ratio of impurity content is the key to ensure the mechanical properties, especially the conductivity.

aluminium Fe element is a catalytic element in aluminum alloy. Trace Fe element has a great influence on conductivity, which should be controlled properly. The trace elements in aluminum alloy also have a great influence on conductivity, such as Mn, Cr, V, Zr and Ti. The content of these elements should also be limited.

(2) The influence of Cu element on the conductivity of rail material and the ratio of elements are as follows

In order to study the effect of Cu on the conductivity of rail profile, the conductivity of Al Mg Si alloy with different content of Cu was analyzed by experiments. The conclusion is that with the increase of Cu content, the conductivity of the alloy first slightly increases and then begins to decline, and there is a peak value in the change of conductivity, that is, when w (Cu) = 0.03%, the conductivity of the alloy is 60.18% IACS.

3.The optimization and regulation of the prescription system of high conductivity aluminum conductor rail

Due to the requirement of conductivity, performance and elongation, but the process conditions and heat treatment requirements of general profiles can not meet, so it is necessary to develop a new process system.

After analysis, in order to ensure the performance of the conductor rail profile, it is necessary to improve the solid solubility of the strengthening term, that is, to dissolve the strengthening term Mg2Si to the maximum extent in the quenching process α aluminium By analyzing the pseudo binary phase diagram of al-mg2si, it is found that the optimum quenching temperature of 6063 aluminum alloy is 450 ℃ - 600 ℃, and the quenching effect is the best.

Export Through the process research, two schemes of low temperature and high speed extrusion and high temperature and low speed extrusion can be adopted. When high temperature and low speed extrusion is adopted, the following problems exist

(1) When the ingot is heated for a long time, the grains grow up and the properties of the final profile decrease;

(2) High heating temperature, long heating time and high heating cost;

(3) Long production cycle and low efficiency;

(4) The temperature difference before and after extrusion is large, and the size of extruded products changes greatly.

The improvement of the performance and conductivity of the final product is achieved by aging treatment. The influence of different temperature and aging time on the conductor rail profile varies greatly. Through the performance and conductivity tests of the following three aging systems of 175 ℃, 195 ℃ and 215 ℃, it is found that the conductivity does not meet the requirements when the strength of 175 ℃ and 215 ℃ meets the requirements, At 195 ℃, the performance and conductivity can meet the requirements. By unifying the properties and conductivity, it is finally determined that the aging temperature at 195 ℃ reaches the maximum in all aspects.