... G 4311,JIS G 43183. production procedure: raw elements(C,Fe,Ni,Mn,Cr,Cu etc.,)--smelted ingots by AOD ... into black surface--pickling into acid liquid--polished by automatically machine--cutting into pieces--checking quality--package4.surface:black,pickling, ... steel angle bar is widely used in chemical, shipping,architecture,machine-made, household products industry, etc.,7.samples are available,pls ...