plastic deformation only stops when the object is cooled to absolute zero (-270somethingish)
solids are only truly solid at absolute zero.
the same idea applies to glass in windowpanes, whereby glass over 100 years old or so, is noticebly thicker at the botttom than the top, due to flowing down the pane and sagging.
ive snapped chains, and im a portly 11st.
i THINK its more to do with application of load, rather than the load itself, ive only done it whileplaying silly buggers on toy bikes
i think it also only occours where ive done something silly with the pin, like pushed in a normal pin to join a chain, causing a weakness on ones side, allowing the outer plate to be forced to pop off the roller due to slight side forces incurred while the chain is crossed from middle ring to big sprocket.
slight side loads (due to gear selection) + dodgey bodge in a pin + Torque = crotch + stem + “Ow!”