It means that the bar or wire rod is deformed while it is hot in order to break up the as-cast structure. This only becomes an issue when you're talking about very large fasteners. I'm confused by your second question. ASTM A 193 is a fastener specification, not a bar specification, meaning you cannot purchase a steel bar according to ASTM A 193. ASTM A 105 (same as ASME SA 105) is a standard for steel forgings for piping applications, and therefore does not pertain to bars or wire rod used for fasteners.