Sadar Bazar, Delhi. Self Drilling Screws. Get Price Quote. 1) Material:Low carbon steel, Alloy steel and st. steel (A2/A4) 2) Surface: Plain, Zinc plated (Cr3 and Cr6), Yellow zinc plated, black oxide, black Zinc plated, Hot Dip Galvanization, Decromate, ruspert. 3) Drill hole, forms mating thread and c operation.