NSSC 550(13Cr-2Ni-2Mo)是新日鐵住金獨自開發的兼具高硬度和高耐蝕性的馬氏體(M)系不銹鋼商品。將此鋼進行適當淬火和回火處理，可以獲得0.2%屈服強度1150N/mm2、抗拉強度1750N/mm2、HV(維氏強度)550的極高強度和硬度，且具有與SUS304鋼同等以上的耐蝕性，加之作為線材制品也具備重要的鍛壓性，故被用作建材中的自動攻絲螺栓、各種高強度銷釘和高強度鏈條等。
High Strength high Rust-Resistant Ferritic Stainless Steel
NSSC 550 is a martensitic grade with remarkably improved quench hardening.
Superior to SUS 304 in corrosion resistance by appropriate addition of Cr and Mo, as well as by control of trace elements.
Superior to SUS 304 in its performance of wire drawings as well as cold-heading.
Applications: Self-tapping screws, High-strength nails, Various kinds of pins, High-strength chains and other applications requiring high hardness and high rust resistance.
