Here is a real puzzler. I just poured a 1/2 round wire ingot from
fresh gold and alloy. When I try to pull it through the draw plate i
get cracking in the wire. Thought I wasn’t annealing often enough.
Tried a second pour same results. thought i wasn’t getting the mold
frame hot enough. poured a third time, same results. Really pissed
about now. Pour a fourth time and ran the ingot through the rolling
mill first and then the draw plate. No problem. perfect wire. same lot
of gold fourth pour. I guess I wasn’t holding my mouth correct?? ? got
any answers for this one?
Hi Frank, The mill compressed the porosity in the ingot. Chances are
the cracks are still there but much tighter and smaller. Bob Martin
St.Paul,MN.
Hey Frank. I normally roll my round wire ingots square and anneal them
before I do anything else. The crystals in a freshly poured ingot are
rather loose. One might note the appearance of a large grain upon
first rolling. Between these crystals, the metal is rather weak.
Rolling and annealing allows the metal to recrystalize with a better
structure.
The ingot has large grains which must be compressed slowly at first(
the mill) before you can apply the greater stresses of of drawing.
That’s my two cents worth. Peter Slone
in the 20s & 30s they used to really STAMP out intricate designs in
gold for rings - the pressure generated to do that was such that it
compressed the metal - making it denser & more stable - guess that
could go for the reclaimed silver in the rolling mill. ive