Carbon Steel Coil Spring 1) Material: 62Si2MnA, 65Mn, SK3,SK4, SK5, SUS301,304 2) ... , gas, diesel oil , electrical machine ,start-up machine,etc.),constant force spring for door ,windows ,electric fans ,machines of lift and down ... in producing springs for various kinds of carbon and stainless steel products and supplies high elastic and heat treatment stainless ...