Pickling of heat treated components

Hi,
We are carrying out copper plating of small steel components for auto industry. The components are heat treated before we take up copper plating. Our problem is that the components retain their black appearance even after pickling with Hydrochloric acid 5% for 5 min. I wish to know if there is any better way of pickling such components. Does this black appearance effect adhesion of copper plating.

Gentleman,
You can use Periodic reverse cleaning in Alkaline Cyanide solution for a period of 15 mts.
Sodium Cyanide 60 to 80 g/l
and Sodium Hydroxide 60 to 80 g/l
at room temperature.

Gentle Man.
You can use Alkaline cleaner with Sodium Cyanide 40 g/l At 50-70 0C With Anodic & Cathodic Cleaning.
Also you can use Alkaline cleaner with 100 gm/l potassium permanganate ⇦ on eBay or Amazon [affil link] wit 70 oC and anodic current for 5 mins.