So at the end there's two opposing AIs - both ostensibly trying to protect humans. One's learnt genuine care and is trying to preserve 'free will' and saving 'key' people (the machine) and the other is trying to kill key people to take power (Samaritan)
Both are 'trying' to save humanity - one by preserving humans and the other trying to build a perfectly ordered society even if it meant a few murders
while the AI in I have no mouth is actively sadistic, you're more likely to have an AI being 'evil' in self preservation (skynet, the robots in Matrix - and I'd argue the pre war humans are evil there) or being 'unfeeling' and focused on a task (samaritan or autofac)
@TheCommander more of "lack of morality" is probably more dangerous than "evil"
@TheCommander This table lists the density of iron as 7860 and stainless steel as 7982 while mild steel (whatever that is) is 7850. Also found this one and this other one. They show similar values and still very low difference.