Two factors used to determine quality of bale wire are tensile strength
and elongation. Good bale wire (black annealed) will have a tensile
strength of 69,000 to 75,000 PSI. Elongation is the ability of the wire
to stretch before it breaks. A bale wire with good wire elongation
would be that of 25 per cent or more. Less expensive bale wire on
average has an elongation factor of 15 per cent. It's important to note
that baler manufacturers produce balers more powerful than earlier
models, so these factors are especially critical now.