#740 Alloy

Thank you for using UNITED'S alloys.

United # 740 Alloy is formulated for 18 Karat Yellow Gold sheet, plate and wire fabrication giving a light yellow color. The #740 Alloy can also be used for Investment Casting if desired. Alloy Information

MELTING
The # 740 Alloy, and fine gold should be melted together in a clean crucible. Put alloy in the bottom of the crucible and fine gold on top. Initial melting temperature should be 1070° C/ 1958° F. Drop temperature somewhat before pouring as listed below. Boric acid flux may be used to keep the metal clean during the melting process. The metal should be mixed well with a stirring rod before pouring to assure a good mix.

POURING TEMPERATURE FOR INGOTS
1030° C, 1886°F.

POURING
Metal should be poured into a preheated, vertical graphite or lightly lubricated iron mold. A steady even pouring motion should be used slowing down at the end of the pour to prevent shrinkage in the top of the ingot. Use a round rod mold for wire and a 2 piece L shaped mold for plate and sheet.

QUENCHING
The metal ingot should be removed from the mold and quenched immediately in pickle solution or water. For heavy ingots a one-minute cool down before quenching prevents quench cracking.

FABRICATION
The metal ingot should be cleaned of all adhering oxide or fluxes before rolling. The ingot should be rolled or drawn to a 50% reduction in size before annealing. After annealing continue the reduction at 50% before annealing again. Clean the ingot after each anneal. Keep rolls, dies and metal clean to prevent defects in the finished stock.

ANNEALING
Annealing temperature 704° C / 1300° F for 20 minutes. Quench immediately in water or pickle solution. A boric acid fire coat should be applied before annealing in open atmosphere ovens to protect the metal from heavy oxidation. Avoid over-annealing wire or plate stock as this can cause excessive grain growth creating orange peel effect on the surface of finished goods.

REMELTING
Use a 50% scrap to fresh mix when remelting to prevent oxide build up in the metal.

INVESTMENT CASTING
Pre-alloy #740 Alloy & Fine Gold, pour into water to make shot.

PRE-ALLOYING TEMPERATURE
1060° - 1070° C, 1940° - 1958° F.

CASTING TEMPERATURE
1025° - 1035° C, 1878° - 1895° F.

FLASK TEMPERATURE
We recommend a slightly higher temperature for 18K.

QUENCH TIME
Wait 5 - 15 minutes before quenching flasks.

TECHNICAL ASSISTANCE
Always available… Call 1-800-999-3463 / 1-800-999-FINE
E-mail / doc@unitedpmr.com
Web-Site / www.unitedpmr.com