... : :Hot rolled,black surface,Hardened&Tempering Chemical composition (for reference only)http://www.forgedroundbar.com/products.asp?id=1300 ... at sight. Application:Extrusion dies and die-casting for alumium,Mandgnesium allay mostly,for copper alloy could usemechaincal press forhing of ... use also Note:1. According to national standard (GB)for our products, if not, supply according to national standards ...