... 631, 200CU, 200CU- Stainless steel spring wire products: A) Material Classification: 200 series: 201, 202 300 series: 301, 302, 304, 304L, ... 304H, 309S, 310S, 316, 316L, 321, 347 400 series: 410, 420, 430, 431, 434 B) Hardness Classification: Soft ... Coppering; Lead plating and so on D) Purpose Classification: For spring; Cold upsetting; Welding; Wire rope E) Physical Classification: Magnetic ...