Question

n a Myth Buster’s episode (samurai swords vs. machine guns) is “demonstrated” that a samurai sword can “cut” a machine gun barrel when the barrel is quenched.  The logic behind is that a continuous shooting followed by a non‐shooting period quenches the machine’s gun barrel.  In order to “truthfully” and “scientifically” replicate such event the Myth Buster’s fellows took a machine gun’s barrel and quench it 5 times.  Their reason was that multiple quenching maximizes the effects of quenching. (a) Use a CCT diagram for low carbon steel (e.g. 1045) and compare it to that of a high carbon steel (e.g. 1080) explain the differences as a function of time and indicate the type of steel that is likely to quench after a shooting period, provide a detail explanation for your conclusion and include both diagrams and cooling paths (2 Points).  (b) Debate the effect of multiple quenching and clearly indicate the number of quenching events required to maximize quenching (2 Points).  (c) Using the non‐steady state diffusion concept indicate what will happen to carbon at the surface of the machine gun’s barrel (assume and indicate conditions, such as temperature, time, etc.).  What happen to carbon?. Use diffusion equations to demonstrate what happen to carbon?. In each quenching event and the changes during the multiple quenching.  Assume 0 wt%C in the atmosphere; select and indicate the dwelling times and temperatures during austenization make the wall thickness for the barrel of 3 mm and indicate how the carbon content changes along the thickness on each quenching event, use diagrams (3 Points)