Black steel hinge pin Surface:BO Process:Machined and turned ... 1,Name: Black steel hinge pin;Steel hinge pin;Black hinge pin 2,For the similar hinge pin,what can we do ... ), Ability for the material of this kind of hinge pin: Grade3.6,4.6,4.8,5.6 ... ,Gr.36,Gr.58,1010,1015,1016,1020,1045,etcAlloy steel4130,4140,G51150,etcStainless steel201,202,301, ... ,especially the cutting/turning parts. Black steel hinge pin