The GATE Grind

GATE 2018 ME (ME2) – Question 23

Casting, Forming and Joining Processes · Casting: patterns, moulds, cores, solidification, riser and gating design, defects · 1 mark · Multiple choice

During solidification of a pure metal, the casting grains near the mould wall are ______.

  1. coarse and randomly oriented
  2. fine and randomly oriented
  3. fine and ordered
  4. coarse and ordered

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Show answer and explanation

Correct answer: (B) fine and randomly oriented

Explanation

Rapid cooling at the cold mould wall creates high undercooling and many heterogeneous nuclei. These form a fine equiaxed chill zone with largely random orientations. Thus **fine and randomly oriented, B**; columnar directional growth develops farther from the wall.