The Chinese idiom "恨铁不成钢" is formed by the sequential combination of the characters 恨 (hate), 铁 (iron), 不 (not), 成 (become), and 钢 (steel), which literally translates to "hate iron for not becoming steel". This phrase originates from the practical context of metallurgy, where iron is expected to be refined into steel, and structurally expresses a cause-effect relationship: the emotion of hatred directed at iron due to its failure to achieve a desired transformation, thus creating a fixed metaphorical expression.