There was a previous Quiz Question involving stress concentration in structural members. That got me to thinking about strength of materials. Here is an interesting fact:
First, modulus of elasticity is a measure of the amount of stretch per cross-sectional area for a given load. For example, the modulus of elasticity of structural steel is in the order of 200 GPa. For specially-treated tool steel the modulus is about 207 GPa—not much better. Yet the tool steel will take ten times the load before rupturing. Does this make sense, and why?
Post your responses in the comments section below.
Update and answer
Greg has the right answer. Hardened steel is nor more rigid than structural steel. It just stretches farther before yielding. It’s counter intuitive that something like a hardened tool bit is just as pliable as an untreated steel bar.