In the process of aluminum alloy die forging, if the casting has defects, it needs to be repaired, and welding repair is a common method. So, what are the methods of welding repair? Langrui Precision Forging Xiaobian has sorted out three common welding repair schemes for everyone. Let's take a look at what these three welding repair schemes are.

1. The advantage of welding repair of electric welding machine is that it can improve working efficiency and repair some big defects. The disadvantage is that the hardness of solder joint will be higher after welding, and it is also easy to produce stress. At the same time, because of this reason, it is easy to be troubled by cracks, and annealing is needed at this time.

2. Argon arc welding and welding repair. This welding repair method is commonly used in aluminum alloy die forging, and it is also a welding repair method that some die manufacturers and repair manufacturers will choose. Its advantages are high efficiency and precision, and there are many kinds of welding wires to choose from. However, when repairing small defects, cracks may occur due to large impact force. If the welding repair is steel, then hard spots may appear after welding repair.

3, cold welding machine welding repair. This is a new repair method. The heat generated during welding repair is relatively small, which has become a widely used welding repair method at present.

The above is the related content of aluminum alloy die forging welding repair method. Among the three welding repair methods, cold welding machine welding repair is considered to be the better one at present. However, this kind of welding repair method requires higher requirements, so friends who want to buy cold welding machine must let the staff know how to operate first.

Measures to reduce coarse grain defects of aluminum alloy precision forgings

The coarse grain defects of aluminum alloy precision forgings are related to forging materials, forging process parameters, forging shape, die temperature and heat treatment process parameters.

1. Material of forgings

Different aluminum alloys are used to make precision forgings, and the probability of coarse grains in their products varies greatly. Al-Zn-Mg-Cu alloy forgings are not easy to produce coarse grain defects, while Al-Cu-Mg and Al-Mg-Si alloy forgings have relatively many coarse grain defects.

2. Forging process parameters and die temperature

Select a reasonable final forging temperature. When the final forging temperature is too low, the forgings are prone to produce coarse grains, especially Al-Cu-Mg and Al-Mg-Si alloys. The final forging temperature must be strictly controlled. For example, the final forging temperature of precision forgings of 2A11(LY11) alloy blades must be higher than 390℃, otherwise coarse grains will easily appear. Forgings of different materials have different requirements for final forging temperature, but all aluminum alloy precision forgings require final forging temperature not lower than 370℃.

Mold preheating temperature should not be too low. Too low die temperature will accelerate the cooling rate of metal in the cavity, make the deformation temperature of metal too low, make it difficult for metal to fill the cavity, and may form the surface of coarse-grained forgings on the cavity. The preheating temperature of the die is related to the forging shape, aluminum alloy quantity and other factors, and it is generally required to be controlled at 300℃ ~ 400℃.

The deformation degree should not be too small. In particular, the degree of deformation after zui fire should not be too small. If the deformation degree is small, recrystallization nuclei are few and the incubation period is long, coarse grains will be formed after reheating (or heat treatment) of precision forgings. If the deformation degree is as small as the critical deformation degree (about 3% ~ 15%), the recrystallization grains will grow rapidly, resulting in coarse grain defects in forgings. In production, the number of finish forging heats and the reduction of each heat should be strictly controlled to avoid the forgings being in a critical deformation state due to too many finish forging heats and too small reduction. Under the condition of ensuring that the metal can fill the cavity and meet the requirements of low streamline, the number of precision forging fires should be reduced as much as possible. Forgings with simple shape and easy forming can be fired at one time, and forgings with complex shape and difficult forming should not be forged more than three times.

Wool allowance should not be too large. Especially for high-rib forgings, if excess metal remains after the metal fills the cavity, if the upper and lower dies continue to close together, the excess metal at the web will flow directly into the burr along the root. The rib groove of the shorter route may cause local coarse grains here due to excessive deformation.

3. Selection of heat treatment parameters

When heat treatment, the quenching temperature is too high and the holding time is too long, which is easy to cause coarse grains of aluminum alloy forgings. Especially Al-Mg-Si and Al-Cu-Mg alloys, the quenching temperature and holding time must be strictly controlled.

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