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When die casting aluminum alloy die castings, the mold temperature is too low, the alloy liquid temperature is too low, the filling speed is too low, the mold release agent is sprayed too much or not blown dry, the gate design is unreasonable, the fast pressure shot point setting is unreasonable, etc., which may cause the die casting to produce cold shut.
The shape of the cold shut is the shape of the liquid when it first flows, with smooth single picks and rounded edges. Therefore, it often appears on the radiograph as a relatively uniform width, lack of change, and smooth strip-shaped black line mirror image. The width of the line appears to be relatively large, and the blackness also changes in the width direction.
The area where the aluminum alloy die casting presents a cold shut is usually the area far from the gate. This is because the metal flow is divided into several streams. The flow front of each stream has shown a condensation state, but it is still filled under the push of the metal diversion behind it. When the metal flow that meets it also has a condensation front, the meeting condensation layer can no longer be fused, and a gap will appear at the joint. Severe cold shut has a certain obstacle to the use of castings, which should be determined according to the use conditions of the castings and the degree of cold shut.
