Black Bar vs Bright Bar

Parameter Hot Rolled Steel Cold Drawn Steel
Manufacturing process Hot rolling Cold drawing
Surface finish Rough and black Smooth and bright
Mechanical properties Lower tensile strength and yield strength Higher tensile strength and yield strength
Cost Less expensive More expensive
Dimensional tolerances Less precise More precise
Straightness Less straight More straight
Workability Harder to work with Easier to work with
Corrosion resistance Lower Higher
Magnetic properties Magnetic Magnetic
Machinability Worse Better
Elongation 20-30% 15-20%
Visual appearance Rough and black Smooth and bright
Net cost of using bright bar vs black bar 10% less expensive 10% more expensive
Heat treatment Can be heat treated to improve mechanical properties Not typically heat treated
Speed of turning Slower Faster
Depth of cut Less More
Scrap loss More Less
Time needed per part Longer Shorter
Cost per part Higher Lower
Details