First of all, HCL does not react with clean steel, and it positively does not react with the metals which are alloyed within the steel. What HCL does is react with the oxide FeO, on the surface of the steel. This process is known in the steel business as “pickling”. When steel is hot-rolled and stored for some time, it develops the oxide FeO on the surface. This oxide is very abrasive and would damage the rolls in the next processing step, which is cold rolling of the steel to a thinner gauge. So, the hot-rolled coils are run through a “pickle line”, where they are subjected to aqueous HCl, which removes the FeO. The coils are then clean (no FeO on the surface) and fit for cold rolling.
Well Fume hoods are used to minimize HCL acid fume.