Virtual Labs

Quantitative Microscopy: (ii) manually estimate the grain size and grain boundary surface area per unit volume of a single-phase polycrystal

1. In the Jeffries' procedure, how are grains that are intersected by the test circle handled ?

a: They are given the weightage of two Explanation

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b: They are counted as full grains Explanation

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c: They are counted as half Explanation

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d: They are subtracted from the total count. Explanation

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2. When performing quantitative grain size analysis, what is the significance of using a higher magnification (e.g., 500×) compared to a lower one (e.g., 100×) ?

a: It is only used for comparison methods, not for measurement Explanation

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b: It allows for a more accurate count of very fine grains Explanation

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c: It is a required step for all ASTM grain size measurement procedures Explanation

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d: It reduces the need for multiple measurements Explanation

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3. Which of the following is NOT a standard procedure for determining grain size ?

a: Comparison method Explanation

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b: Intercept method Explanation

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c: Area fraction method Explanation

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d: Jeffries' procedure method Explanation

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4. For a material with a known ASTM grain size number (n), the average number of grains per square inch at a magnification of 100× (N) is calculated using which formula ?

a: N = 2^n-1 Explanation

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b: N = 2ⁿ⁺¹ Explanation

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c: N = n + 100 Explanation

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d: N = 2n Explanation

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5. What is the primary purpose of using the intercept method for grain size measurement ?

a: To determine the percentage of different phases in a microstructure Explanation

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b: To count the number of grain boundaries intersecting a test line Explanation

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c: To measure the total area of all grains in a micrograph Explanation

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d: To visually compare the microstructure to a standard chart Explanation

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6. Jeffries method for grain size measurement involves :

a: Comparing the microstructure to a standardized chart Explanation

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b: Counting the number of grain boundary intersections with a line of known length Explanation

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c: Counting the number of grains completely inside and those intersecting the perimeter of a known area Explanation

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d: Calculating the mean intercept length of the grains Explanation

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