Which defect occurs when two portions of metal do not unite during casting?

Which defect occurs when two portions of metal do not unite during casting?

• A. Cold Shut
• B. Crack lamination
• C. Degradation
• D. Hardness

Answer: (A)

When two portions of molten metal fail to fuse into a single piece during casting, the resulting defect is a cold shut. This occurs because the molten metal doesn’t flow and unite properly before solidification, leaving a seam or weak boundary where the two fronts meet. It’s most often caused by insufficient fluidity or metal flow—factors like pouring temperature being too low, gates or runners not providing adequate fill, or the metal cooling and losing its ability to fuse before the mold cavity is fully filled. You might see a line on the surface or an internal separation where the streams didn’t weld together. Preventing cold shuts involves ensuring adequate feeding and flow: optimize gating design and risers, maintain proper pour temperature, reduce mold chill, and improve venting so the metal fills smoothly and remains molten long enough to fuse. Other terms describe different issues, such as general material degradation or a hardness value, which are not the defect that arises from two metal portions failing to unite during casting.

When two portions of molten metal fail to fuse into a single piece during casting, the resulting defect is a cold shut. This occurs because the molten metal doesn’t flow and unite properly before solidification, leaving a seam or weak boundary where the two fronts meet. It’s most often caused by insufficient fluidity or metal flow—factors like pouring temperature being too low, gates or runners not providing adequate fill, or the metal cooling and losing its ability to fuse before the mold cavity is fully filled. You might see a line on the surface or an internal separation where the streams didn’t weld together. Preventing cold shuts involves ensuring adequate feeding and flow: optimize gating design and risers, maintain proper pour temperature, reduce mold chill, and improve venting so the metal fills smoothly and remains molten long enough to fuse. Other terms describe different issues, such as general material degradation or a hardness value, which are not the defect that arises from two metal portions failing to unite during casting.