@Humpleupagus @sj_zero Now imagine a car engine block or frame. Yeah rust sucks and saving weight helps for emissions targets and better mpg, but, knowing how much energy it takes to process and fab metal, it's orders of magnitude more efficient to have something that lasts for potentially 50+ years vs 20. Only iron and titanium have a fatigue curve which is like flat armor in a videogame— functionally zero endurance damage if at or below the fatigue limit.