The little metal pegs on a snow blower or a fuse in a circuit are examples I can think of.
Sacrificial Part is the general term.
Another example would be a sacrificial piece of metal that will attract the corrosion over that of the metal of a boats prop under the waterline
Pegs on a snowblower are called shear pins.
‘Failsafe’ the word you are looking for?
“Ackshyually” incoming…
Failsafe has a specific meaning, describing a system that enters an inherently safe state in the case of a failure.
For example, semi truck parking brakes are actually disengaged by applying air pressure to the system; without air pressure the brakes are engaged automatically by heavy springs. Therefore most failures in the braking system would just result in being unable to disengage the brakes, as opposed to a truck rolling away.
So, while a sacrificial component like OP is describing could be designed as part of a failsafe, generally it’s a different design principle at play.
In german its “Sollbruchstelle”, that would translate to “intended breaking point”.
Mechanical fuse. Typically composed of shear pins or can be geartrain shafts manufactured with intentionally thinner cross-sections placed at strategic points. A plastic cog in some power tools serves a similar purpose.
