Magnesium alloy plate rolling method (2)

This article mainly discusses the special rolling method in the magnesium alloy rolling method.

Special rolling

2.1 asynchronous rolling (DSR)

The principle of asynchronous rolling is shown in Figure 3 below. It changes the speed of the surface of the two working rollers by changing the diameter, speed, and friction conditions of the upper and lower rolls. The friction horizontal pressure has a hindrance to deformation, which significantly reduces the total pressure when rolling deformation. Therefore, asynchronous rolling is used to fine the board grains, and the base surface of the board's base surface is weakened, the yield strength is reduced, and the plasticity is improved.

2.2 Cross -rolling

After cross -rolling, the grains of the plates become smaller, the tissue is uniform and stable. At the same time, the base surface weaving is improved, which improves the plastic toughness of the plate, but the stamping forming performance is slightly reduced. At the same time, cross -rolling technology can optimize the opposite sex of the magnesium alloy, making the mechanical properties more uniform, and the mechanical properties of the board in different directions are less on the board. In addition, after cross -rolling, the base fabric improvement of the magnesium alloy plate material and the fineness of the grains enhance the strength of the board, and the bloating performance of the plate is reduced. Because the rolling method has some restrictions on the board, the cross -rolling processing process is complicated, and it is not suitable for the large -scale preparation of magnesium alloy plates.

2.3 Great strain rolling (LSR)

Large strain rolling process is a drama plastic deformation technology, which can reduce the size of the grain size and obtain ultra -fine crystal tissue materials. Big stress rolling can be divided into cumulative stack rolling and equal diameter rolling.

(1) Cumulative stacking

Cumulative stacking is one of the strenuous plastic deformation techniques. This process method is at a certain temperature, the two -piece size metal plates obtained after processing hardening and abandoning will be carried out. This process has repeatedly stacked and welded, so that the plates obtained have a large response.

Cumulative stacking technology is not only low in equipment investment, but also simpler technology than other methods, high finished product ratio, but also not limiting the size of the plate rolling. It is considered to be the most expected to prepare the industrial production of large -scale, high economy, and high -performance fine crystal magnesium alloy plates. This technology has seductive application prospects, but there are still some disadvantages when preparing magnesium alloy plates in this method, such as large plastic deformation and cracking in thick plates during processing. Wait. The current cumulative stacking is mainly used to make high -performance thin plates.

(2) Equal rolling

Equal rolling is a special rolling technology that combines rolling and large shear deformation based on the basic principles of equivalent angle squeeze. The corner rolling process can improve the grain size of magnesium alloy plates to reduce the size and generate a large number of fine twins, thereby improving the strength of the board and the capacity of room temperature plastic deformation.

In addition, the rolled plates after the corner of the phrase will rotate under the action of shear force, causing the base surface orientation to evolve into a non -base surface orientation, which makes the base surface weakened significantly weaken. This process has a large application prospect. Although the disadvantages of being easily stable and wrinkled and the rolling process are unstable when rolling thin plates, as the rolling channel becomes larger, the strength of the board becomes smaller, plastic and forming Sex has improved significantly.

2.4 Electric pulse rod

The two rolls are insulating. The process of applying pulse current at the same time is called electrical pulse rod. It perfectly combines the electrical effect and plasticity of the current. Under the action of electrical plasticity, its plasticity has been greatly improved. There are many advantages of electrical pulse rod technology, such as reducing the deformation resistance of materials, improving the mechanical properties and forming limit of materials, reducing processing processes and improving product quality. Therefore, the electrical plastic processing electrical pulse rod technology has great application prospects in magnesium alloy plastic processing.

Study of rolling forming edge

The special crystal structure and physical properties of magnesium alloy leads to defects such as edge cracks during rolling. Cracking not only reduces the material rate of the plate, but also expands during the subsequent rolling process, destroying the continuity of the production process, and seriously restricted the promotion and application of magnesium alloy. Therefore, reducing or eliminating the fissure defects of magnesium alloy plates and improving the performance of the finished product has become a hot issue in the material field research.

Factors affecting edge cracks

(1) Rolling temperature: Temperature is one of the important factors affecting the rolling process of magnesium alloy plates. Magnesium alloy is poorly plastic deformation at room temperature, and generally needs to be rolled after heating.

(2) Pressing the system: The lowering system contains both the maximum pressure of the rolled lane and the total pressure under the accumulation of the rolling course. First of all, after the subversion rate of the road reaches a certain value, the magnesium alloy plate will cause crack defects. Secondly, the overall pressure rate also has a great impact on the formation of edge fissure defects.

(3) Rolling speed: The rolling speed also has an important impact on the production of magnesium alloy plates. High -speed rolling can improve the rolling performance of magnesium alloy plates.

(4) Stress status: In the process of metal deformation, most cracks are highly deformed and encountered by uneven deformation and encountering obstacles (crystal boundaries or second phases). When the stress concentration reaches the critical break strength, cracks will be generated, as well as the production of magnesium alloy plates.