All Purpose Light Yellow Alloy for 18K

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740 18K Light Yellow All-Purpose Alloy - 1 oz.

Our Price:$52.95

Product Code: UN740

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Description

Instructions

#740 Light Yellow (18K) All Purpose Alloy 1 oz. (28 grams).

Alloy #740

Purpose

Mix alloy #740 with fine gold to obtain 18K bright yellow gold for sheet, plate and wire fabrication.
Can also be used for investment casting if desired.

Melting

#740 alloy and fine gold should be melted together in a clean crucible and fine gold on top.
Initial melting temperature should be 1070° C / 1958° F.
Drop temperature somewhat before pouring as listed below.
Boracic 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

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 the 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 boracic fire coat should be applied before annealing in an open atmosphere oven to protect the metal from heavy oxidation.
Avoid over-annealing wire or plate stock as this can cause excessive grain growth, creating an orange peel effect on the surface of finished goods.

Re-Melting