Coastal solar farms, metal roofing and offshore construction face severe salt spray, UV and temperature erosion that quickly rust ordinary fasteners. EC Fastener bi-metal self-drilling screws perfectly solve this pain point.Conventional single-metal screws force a trade-off: carbon steel drills well but rusts fast, while pure stainless steel struggles to cut hard steel. Our bi-metal screws weld hardened alloy steel drill tips to SS304/SS316 stainless steel shanks. They finish drilling, tapping and fixing in one step without pre-drilling, and stand up to long-term corrosive working conditions.We offer multiple customized material & coating options. The SS316 version passes over 2000 hours neutral salt spray test for seaside projects; RXB coated types resist acid and alkali for chemical factories. Heat-treated drill points easily pierce 6mm thick steel, boosting on-site installation efficiency greatly.Based in the Yangtze River Delta with 25 years fastener manufacturing experience, EC Fastener holds ISO 9001 certification. Our products supply mainstream overseas retail chains including Bunnings, Home Depot and B&Q. We provide complete REACH, RoHS and material test certificates, plus OEM marking, private packaging and integrated container logistics.If you source fasteners for solar brackets, metal roof systems or coastal engineering projects, check our full bi-metal screw lineup at ecindustry.com. Contact us for free samples, technical datasheets and competitive CIF quotes.