Gold pressure processing

The method of press working a metal in an allowable range of plastic deformation by means of metal plastic, to change the shape of the blank debate and make-inch, to obtain the desired product. According to the different conditions such as temperature and speed of the plastic deformation process, the deformation can be divided into thermal deformation with complete recrystallization without residual Beijing hardening, temperature deformation accompanied by internal stress recovery, and cold deformation without recrystallization or recrystallization. Three forms.

The plasticity of gold is very good, and there is no particular difficulty in processing under cold and hot conditions.

Gold and gold-based alloy flat belts (flattened strips) are processed by a method of rolling a wire, and the general specifications are: 0.15 to 5 mm in width and 4 to 5 mm in thickness. The main line is a flattening machine or a two-roll mill. For high-strength thin strips, it is rolled by a multi-roll mill. The wire diameter of the rolled flat strip is determined according to the finished product size. If b/h ≤ 10 (b width, h is thickness), the wire diameter is calculated on the principle that the finished product and the blank have the same area. If b/h>10, the wire diameter is calculated according to the formula

Calculate, in the formula Ky - the broadening factor of rolling, related to the alloy composition, for gold Ky = 1.03 ~ 1.1.

Gold has excellent ductility. In the cold working process, continuous processing without intermediate annealing can be performed. The "Sheepkin Gold" technique, which has been circulated for a long time, can be processed into a semi-transparent state. 0.1 ~ 1μm thickness of the foil manually hammering processing methods have been for thousands of years, this process is still used at home and abroad since processing gold and silver foil bimetallic foil. The foil sheets are stacked with a gasket to form a crucible, which is stuffed in a leather shell, hammered with a chain of 2 to 8 kg weight, and hammered for several times to reach the required size. After each hammering, it is necessary to disassemble and re-lamination, and then repeat the next upset. The liner is typically made with a special treatment of the cecal membrane to ensure its integrity and elasticity.

Gold has a low mechanical strength, a high elongation, and is easy to process. Various pressure processing methods can be used at temperatures below its melting point. For cold drawing, the processing rate of the pass can reach 20%, the total processing rate between the two annealings can reach more than 95%, and the annealing temperature is 400-500 °C. High purity gold wire with a purity of 99.9999% has the property of "self-annealing" at room temperature, which affects the use of fine gold wire. It has been proved that adding 0.01% Fe, Cu, Ag, Pt and Pb to high-purity gold can raise the recrystallization temperature from room temperature to 100 °C; adding 0.01% Mg, Al, Si, Ni, Sb, Te and Bi gold It can be annealed at 200 ° C or higher.