EFFECT OF THE DEGREE OF CHARCOAL CALCINATION ON THE QUALITY OF COPPER WIRE RODS

摘要

The most serious defects in cast billets are pores and cracks resulting from hydrogen and oxygen dissolving in metal; the effect is identical to "hydrogen sickness" of copper when saturated by hydrogen. The formation of water vapors in ingots leads to the appearance of pores and cracks in solid metal. There is a simultaneous increase in brittleness and a drop in the metal strength - particularly at high temperatures. For example, when poorly-calcined charcoal is charged into a casting bath, the billets - when removed from a rotary casting machine - fracture, under their own weight, to pieces 200-300 mm long. Only after the charcoal has been calcined (for 10-15 minutes) does billet fracture cease and the process proceeds normally. Cast billets begin to fracture when the hydrogen content is >7 centre dot 10~(-4) percent (in other cases, whether cracks occur will be determined by the charcoal quality; the maximum hydrogen content in cast billets with cracks is 10~(-7) percent; the true hydrogen content when the billets are brittle was not established).