Melting time vs Temperature and Mass

Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
5 replies · 2K views
h1a8
Messages
86
Reaction score
4
I recently saw the movie “Man of Steel”. In Superman’s fight with Zod, Superman cuts (by melting) a steel I-beam, that Zod is about to hit him with, with a swipe of his heat vision. To melt steel that fast (under 3 seconds) requires a large temperature. My question is how can we calculate the temperature needed to melt (or heat to a certain temperature) steel of a certain mass within a certain amount or time? Basically a temperature vs time and mass function is what I’m trying to achieve.

Thanks!
 
Physics news on Phys.org
There is no such thing. If the steel gets hot enough it will melt without delay (well, maybe picoseconds). How to make a steel bar hot enough throughout the bar is a different question.
 
mfb said:
There is no such thing. If the steel gets hot enough it will melt without delay (well, maybe picoseconds). How to make a steel bar hot enough throughout the bar is a different question.

So a 3000 degree arc from a wielding torch could melt a certain amount of steel the same speed as a 2500 degrees arc could?

According to Newtons Law of Heating, it’s takes a certain amount of time for a medium to heat an object to a certain temperature.
 
h1a8 said:
it’s takes a certain amount of time for a medium to heat an object to a certain temperature
That is a different question than in your original post.
If you consider heat flow from some external heating source to the metal you'll have to consider thermal conductivity, and in general you will need numerical simulations because there is no analytic solution.
 
mfb said:
That is a different question than in your original post.
If you consider heat flow from some external heating source to the metal you'll have to consider thermal conductivity, and in general you will need numerical simulations because there is no analytic solution.
I seen the equation
Rate of Heat transfer = k(T1 - T2) /d
Where K is the thermal conductivity, T1 is the temperature of the object 1, T2 is the temperature of object 2,and d is the thickness of the object.
I'm basically trying to calculate how long it will take for a substance of certain size and mass to melt under a given ambient temperature.
 
h1a8 said:
Where K is the thermal conductivity, T1 is the temperature of the object 1, T2 is the temperature of object 2,and d is the thickness of the object.
That works for flat objects where opposing surfaces have the same constant temperature and there is a steady flow of heat. That is not the situation you have, although that formula can be used in simulations for small mass elements and small time steps.
h1a8 said:
I'm basically trying to calculate how long it will take for a substance of certain size and mass to melt under a given ambient temperature.
This will likely need a numerical simulation.