Does heating weaken the strong nuclear/electromagnetic forces

[RobbyQ]

In this steel forging video, does the heat weaken the strong nuclear and electromagnetic forces allowing compression?

 

[ohwilleke]

The strong force and electromagnetic force both change in strength with the momentum exchange present in the interaction (i.e. in high energy/high temperature interactions).

At high energies, the strong force gets weaker, and the electromagnetic force gets stronger.

The electromagnetic force coupling constant is about 1/137 at minimal energies, and about 1/127.5 at the Z boson mass (i.e. about 91.1876 GeV which is about 10.6 billion degrees Kelvin).

The chart below shows inverse of the strength of the three Standard Model forces with energy scale: U(1) corresponds to electromagnetism, SU(2) corresponds to the weak force, and SU(3) corresponds to the strong force (the strong force hits a peak and then gets weaker again at energy scales below those depicted in the first figure, as shown in the second figure).

As shown here for the strong force:

The strong force coupling constant, which is 0.1184(7) at the Z boson mass, would be about 0.0969 at 730 GeV and about 0.0872 at 1460 GeV, in the Standard Model.

See also here and here.

But, the momentum exchange scale in the circumstances show in the video are minimal relative to the energy scales at which this running of coupling constant strength with energy is discernible.

Also, the force between atoms in the nucleus is not directly the strong force, it is a residual strong force caused by meson exchange between protons and neutrons (the single biggest component is pion exchange, by kaons and other light neutral mesons are also exchanged).

So, while the effect described does exist at extremely high energies, it does not explain the behavior of steel at high energies.

Changes in the behavior of steel at these temperatures is entirely an electromagnetic force matter, with no impact from the weak force or strong force or residual strong force that binds nuclei. And, the changes observed aren't due to a change in the strength of the electromagnetic force coupling constant at these higher temperatures.

6000 degrees Kelvin or less (which is in the ballpark of steel plant temperatures) is about 51.6 keV. This is about a million times cooler than the temperatures at which the running of the coupling constants would have a measurable effect.

 

[RobbyQ]

6000 degrees Kelvin or less (which is in the ballpark of steel plant temperatures) is about 51.6 keV. This is about a million times cooler than the temperatures at which the running of the coupling constants would have a measurable effect.

Thanks for your response.
But even at 6000 K does this offer any weakness to the electromagnetic forces and thus allow the steel to be more malleable. If not, what is making the steel malleable which allows them to shape it easier?

EDIT: Upon further reading I believe the heating allows recrystallization which is usually accompanied by a reduction in the strength and hardness of a material and a simultaneous increase in the ductility.

But even so, if strength and harness are effected what forces (if any) have been affected?

 

[ohwilleke]

Thanks for your response.
But even at 6000 K does this offer any weakness to the electromagnetic forces and thus allow the steel to be more malleable. If not, what is making the steel malleable which allows them to shape it easier?

EDIT: Upon further reading I believe the heating allows recrystallization which is usually accompanied by a reduction in the strength and hardness of a material and a simultaneous increase in the ductility.

But even so, if strength and harness are effected what forces (if any) have been affected?

The electromagnetic force is a fraction of a percentage point stronger at 6000 K than it is at room temperature.

This does not give rise to the effect seen.

The electromagnetic bonds in steel are pretty weak to start with at room temperature, and the heat overcomes those bonds, giving it different properties.

Put another way, the electromagnetic force between the atoms holding them together isn't materially different in strength. What is different is the energy pushing against that force, mostly kinetic energy.

But, thinking about the behavior of a metallic alloy in terms of underlying fundamental physics really isn't helpful. It is better to think of it as more of an inorganic chemistry/condensed matter physics problem, rather than in terms of the Standard Model force interactions involved which are most natural to think about in isolated particle interaction not complex structured mixes of particles. Condensed matter physics has formulas inspired but not necessary proven from first principles from Standard Model physics that provider greater understanding and deal with the measured quantities more directly.