as hard as iron

This paper reports the production principle and technology of metals material using the disused hard iron-bounded alloy as materials, using the method of inorganic acid dissolving processing and combining to roast, precipitate, crystallize, reduce etc.

探讨了用无机酸处理废铁基硬质合金的方法，介绍了焙烧、浸取、水解、结晶和还原等过程参数，提出了分离合金组元、制取金属材料与化学试剂的原理和生产工艺。

Underneath the jersey he wore were muscles as hard as iron.

在他身穿的那一件球衫下面,是一身结实的肌肉.

it is as hard as iron.

它和铁一样坚硬。

And again she clung to him, ignoring the raking pain as iron-hard claws combed her body.

而且再一次她黏附于他, 不理睬向船尾痛苦如铁 - 难的爪梳头发了她的身体.