Q1 Austenitized 40 mm diameter 5140 alloy steel bar is quenched in agitated oil Predict what is the Rockwell hardness of this bar will be at a its surface and b its center c What do you think about the difference in hardness number between the center and surface d Differentiate between hardness and hardenability e Rank the steels in the figure below from lowest to highest hardenability and explain why 600 Bar diameter mm 100 80 60 40 20 0 300 0 0 Cooling rate at 700 C C sec 150 5 25 125 8 S 34 R 10 M R Agitated oil 15 20 LL 5 5 2 3 4 Distance from quenched end De Jominy distance 4 3 19 Bar diameter in LLO 25 mm 1 in Where C center S surface M R mid radius Hardness Rockwell C 288928 65 60 55 50 45 40 30 25 20 JI 15 10 0 1 2 10 5140 20 30 Distance from quenched end mm 4340 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 Distance from quenched end sixteenths of an inch 40 9840 4140 8640 50