BigH...one other reason for the lack of chemistry in A615 is that most rebar in the US is produced from recycled steel from a variety of sources. As long as the physical properties are met, there is little attention paid to the metallurgy of rebar.
Almost all of the rebar in our area comes from electric arc furnaces, charged with the lowest grade of scrap metal you can find (crushed auto bodies with all the plastic and die-cast aluminum parts still on there, crushed washing machines/dryers, etc.)...the slag from the process is almost unusable (expansive, inconsistent properties).