630 is a martensitic precipitation, age- hardening 17% chromium – 4% nickel stainless steel flux-coated electrode designed for welding ASTM A564 Type 630 and other martensitic PH stainless steels such as 15-5. Weld deposits have excellent mechanical properties with high strength and hardness. Most commonly used in high temperature and abrasion resistant environments such as found in the petrochemical and aerospace industries. 630 (Aka as 17-4PH)