"will be hardened" is grammatically correct and can be used in written English.
It is a future tense construction used to describe something that will become harder or more resilient in the future. Example: With proper training and practice, the young athlete's muscles will be hardened, allowing her to excel in her sport.
Others argue that all publicity is good and that the eventual Republican winner will be hardened, as Romney said Wednesday, for facing Obama.
The longer we wait before returning to the table and reaching an agreement, the more blood will be spilled, the more hearts will be hardened.
The figures' costumes will be hardened with a resin, a mold will be made of the entire body and molten bronze poured into that.
Next year they'll have a new stadium, they've already made three sound signings in Lance Hohaia, Anthony Laffranchi and Mark Flanagan, and the youngsters will be hardened by their 2011 experience.
The suspicion that Strachan is "not one of us and never will be" hardened when he appeared on Celtic TV just days into his reign and informed its subscribers that he was a Hibernian fan, not altogether unusual for a lad who grew up in Edinburgh on Easter Road's doorstep.
Fire the mold in the kiln so it will be hardened enough, or annealed, to cast glass in.
Even robots working there will need to be hardened against the radiation, and also dexterous enough to navigate through what is, essentially, a bomb site.
To take advantage of fast-charging batteries, a car's electrics will have to be hardened up to cope with the huge amperage involved.
However, seedlings that are grown indoors will need to be "hardened off" (gradually adjusted to outdoor climates) rather than just being moved outdoors when the weather is nice.
"Views will not set, but be hardened over the summer.
But our people and our Government must accept another reality: as potential official American targets are "hardened," terrorists will simply turn to non-official soft targets -- businesses, schools, tourists and so on.
