Question

Data Collected During the Charpy Impact Tests Two types of steel specimens (BLUE and RED) were used in Charpy testing. The specimens were tested at one of three possible temperatures (-10°F, 32°F or 72°F). Below are the results from this testing. Temperature (°F) 72 72 72 32 32 32 Reading (lb-ft) 191 202 175 25 32 26 32 22 10 12 Type Blue Blue Blue Blue Blue Blue Blue Blue Blue Blue Red Red Red Red Red Red Red Red Red Red -10 -10 -10 72 72 14 45 40 72 38 32 12 14 32 32 16 32 11 5 -10 -10 -10 3 5

Answer 1

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о 250 200 150 Reading of Energy 100 50 С -10 10 30 50 70 90 Temperatures

Red and blue dots explain its values of energy for the corresponding temperatures.

Trend Analysis: we see that as temperature reduces( from + to - ) the energy absoved for fracture also reduces. That means at higher temperatures, the materials absorbes more energy before fracture/failure. Also red type are below blue type irrespective of temperatures, making us understand that, red type steel occupies lesser area(less toughness) in the graph compared to blue type steel and are prone to fail faster.

Blue type steels are more ductile compared to red type.and especially those specimens from blue type , at higher temperatures will absorb more energy and eventually fail.

Effect of C on Toughness:

As % of Carbon increases, the hardness, strength, hardenability increases but at the same time ductility mitigates, finally resulting in a lower toughness. This is one of the reasons brittle materials with more carbon content absorbs less energy while carrying out impact test and fails quickly