When two streams of molten metal do not fuse with each other during casting of an automobiles part, the defect is known as

Explanation:

Cold Shut

• A cold shut is a casting defect that occurs when two streams of molten metal flow together but fail to fuse completely. This results in a weak spot or seam in the casting, which can lead to reduced strength and potential failure of the part under stress. This defect is particularly common in components with complex geometries, such as automobile parts, where molten metal has to flow through intricate paths.

Formation of Cold Shut: A cold shut occurs due to improper fusion of molten metal streams. This can be attributed to factors such as:

• Low pouring temperature of the molten metal, which reduces its fluidity.
• Slow filling of the mold cavity, causing the molten metal to cool and solidify prematurely.
• Improper gating and riser design, leading to turbulence or uneven flow of molten metal.
• Inadequate venting of the mold, causing air pockets and preventing proper flow of metal.

Characteristics:

• Cold shuts appear as thin lines or seams on the surface of the casting.
• These seams are typically weak points where the metal is not fully bonded.
• The defect can often be detected visually or through non-destructive testing methods such as X-rays or ultrasonic testing.

Prevention:

To prevent cold shut defects, the following measures can be taken:

• Maintain proper pouring temperature to ensure adequate fluidity of the molten metal.
• Optimize gating and riser systems to ensure smooth and uniform flow of molten metal into the mold cavity.
• Use proper venting in the mold to eliminate air pockets and ensure even filling.
• Design the mold cavity to minimize abrupt changes in geometry, which can disrupt the flow of molten metal.
• Use materials with appropriate thermal properties for the mold to control cooling rates and prevent premature solidification.

Applications: Understanding and preventing cold shut defects is crucial in industries such as automotive manufacturing, where the strength and reliability of cast components are critical for safety and performance.