铁石心肠的英语:heart of stone [steel]; a rocky [stony] heart; be dead to all feelings; be iron-hearted [hardhearted]; marble-hearted; steel one's heart against pity; unmoved by feelings
铁石心肠的法语:avoir un cœur de fer et de pierre;cœur impitoyable;avoir cœur dur;être sans cœur