Will steel fibers rust?

Outdoor Applications With Cracks-Laboratory and field-testing of cracked SFRC in environments containing chlorides has indicated that the cracks in concrete can lead to corrosion of the fibers passing across the crack. However, hairline cracks (crack widths < 0.004-in.) do not allow corrosion of steel fibers passing across the crack. If cracks wider than 0.004-in. are limited in depth, the consequences of this localized corrosion are not structurally significant.