Method of making copper wire rod with low semi-softening temperature, method of making copper wire and copper wire
A method of making a copper wire rod with low semi-softening temperature includes melting a raw material copper to have a copper melt, adjusting concentrations of oxygen and sulfur included in the copper melt to be not more than 20 ppm and not more than 6 ppm, respectively, continuously casting the adjusted copper melt at temperature not higher than 1120° C. to have a cast bar, and hot-rolling the cast bar in a temperature range of 850° C. to 550° C.
1. A method of making a low-oxygen copper wire rod with a low semi-softening temperature, said method comprising:
melting a raw material copper to have a copper melt;
adjusting concentrations of oxygen included in the copper melt and sulfur included in the copper melt such that the concentration of the sulfur to be not more than 6 ppm without adding any other metals;
continuously casting the adjusted copper melt having a composition with an oxygen concentration more than 10 ppm and not more than 20 ppm, a sulfur concentration not more than 6 ppm, and a balance of copper and inevitable impurities at a temperature not higher than 1120° C. to have a cast bar; and
hot-rolling the cast bar in a temperature range of 850° C. to 550° C.,
wherein the temperature range comprises a rolling initiation temperature of 850° C. and a rolling termination temperature of 550° C.
2. A method of making a copper wire, comprising:
cold working the copper wire rod with the low semi-softening temperature made by the method according to claim 1 at a working ratio of not less than 90%; and
annealing the copper wire rod continuously on a same production line.
3. A copper wire made by the method according to claim 2 , wherein the low semi-softening temperature is not more than 160° C.
4. The method according to claim 1 , wherein the concentration of oxygen included in the copper melt is higher than the concentration of sulfur included in the copper melt.
5. The method according to claim 1 , wherein the concentration of oxygen included in the copper melt is two times to four times higher than the concentration of the sulfur included in the copper melt.
6. The method according to claim 1 , wherein said hot-rolling the cast bar comprises passing the cast bar through a plurality of mill rolls.
7. The method according to claim 6 , wherein the rolling initiation temperature is measured just before a first mill roll of said mill rolls in a travelling direction of the cast bar, and the rolling termination temperature is measured just after a final mill roll of said mill rolls in the travelling direction of the cast bar.
8. The method according to claim 1 , wherein the rolling initiation temperature is set such that said sulfur included in the copper melt is deposited as an oxide in a diffusion reaction.
9. The method according to claim 1 , wherein the raw material copper comprises an electrolytic copper.