Extremely sturdy and durable (for objects); resolute and unyielding (for character).
尽管面临重重困难，他依然钢打铁铸，毫不退缩。
Despite facing numerous difficulties, he remained resolute and unyielding, never backing down.
Next Idiom
Extremely sturdy and durable (for objects); resolute and unyielding (for character).