Black steel hex screw Process:Mahined and turned Surface:BO SGS audited ... 1,Name:Black steel hex screw;black hex screw;steel hex screw 2,For the similar hex screw,what can we do ... Ability for the material of this kind of hex screw: Grade3.6,4.6,4.8,5.6,6. ... ) plated,anodic oxidation,etc Dip plating black oxide coating,hot dip galvanizing,etc Flame plating Light oil,spray coating,electrophoretic coating ...