  Pressure plays a vital role in changing the transport properties of matter.
To understand this phenomenon at a microscopic level, we here focus on a more
fundamental problem, i.e., how pressure affects the thermalization properties
of solids. As illustrating examples, we study the thermalization behavior of
the monatomic chain and the mass-disordered chain of
Fermi-Pasta-Ulam-Tsingou-$\beta$ under different strains in the thermodynamic
limit. It is found that the pressure-induced change in nonintegrability results
in qualitatively different thermalization processes for the two kinds of
chains. However, for both cases, the thermalization time follows the same law
-- it is inversely proportional to the square of the nonintegrability strength.
This result suggests that pressure can significantly change the integrability
of a system, which provides a new perspective for understanding the
pressure-dependent thermal transport behavior.
