Black oxide stud bolt is carbon steel threaded stud with black oxide finish. Black oxide is chemical conversion coating instead of electroplating, forming matte black surface. It provides slight rust protection and good lubricity during tightening. Low salt spray resistance, only suitable for dry indoor environment. Common strength classes: 8.8, 10.9. Stud bolt has threads on both ends, used to connect two thick components, widely applied in flanges, pressure vessels, machinery and mould assemblies.