Rust had eaten into the metal.

这金属已经锈坏。

《牛津词典》

One great advantage of this metal is that it doesn't rust.

这金属最大的一个优点就是不生锈。

《牛津词典》

It rots the window frames, cakes the panes with salt, and corrodes anything metal down to brown, bleeding rust.

它腐朽了窗棂，晒得在窗玻璃上结了一层盐，无论任何金属都被腐蚀成了泛着棕色的血锈色。

youdao

Rust is the metal (Fe for iron) turning to the oxide (Fe2O3 normally for iron although there are other oxides).

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Rust is visible on the metal parts and there are signs of wear and tear.

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This is great news for website designers, Internet entrepreneurs, registered nurses, and masseuses in California, but grim tidings for traditional metal bashers in the rust belt manufacturing states like Michigan, Indiana, and Ohio.

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