Angle valves are commonly used in household sanitary systems. Usually, they are forged in brass. It not only requires excellent corrosion resistance performance of the material, but also qualified mechanical properties and tissue compactness. Mostly, brass forging companies use C37700 forged brass as the forging material of angle valve body. However, compared with C37700, DR brass has better dezincification resistance performance and it reaches the other properties of C37700 brass forgings. It is proposed to use the DR copper for the forging of the angle valve body and at the same time it reaches the other properties of the C37700 forged brass.
As is known to all, C37700 brass has excellent forging properties, so it is called forged brass. C37700 has excellent forging properties is because it is (α+β) two-phase structure and about 40% is the β phase, while the β phase has good plasticity at high temperatures, improving its hot workability. Although the DR brass is also a duplex brass, the β phase content in the structure is less, generally not more than 10%, and the α phase is more, so the high temperature plasticity is poor, and the forging performance is also poor. With hot die forging, the customers’ requirements can be met perfectly.
Forging Temperature Selection
The copper content (mass fraction) in DR copper is between 62.5% and 63.5% and zinc content is between 33.5% and 34.5%. With the binary phase diagram of copper-zinc, it can be seen that DR copper undergoes (α+β) to β transformation when the temperature is over 800 °C and the high temperature microstructure is all β phase, which has good plasticity. Therefore, the initial forging temperature should be over 800 °C. However, the grains will be coarse when the temperature is too high, so a suitable initial forging temperature is preferably set at 825 °C. The common forging temperature of C37700 forged brass does not exceed 800 °C. The final copper forging temperature of C37700 forged brass is generally 650 °C. We set the final forging temperature of DR copper to 700 °C.
Die Temperature Selection and Control
Because the taper core-pulling die base is larger in volume and it absorbs more heat, while the angle valve body itself and its forging die are smaller in volume and the density of the release agent is large, so forging die cavity dissipates heat faster. Therefore, the die temperature is easy to decrease during the forging process, which affects the forming quality and is prone to underfill. In order to solve this problem, it not only requires to maintain continuous operation during the production process and to use the forging heat to maintain the die temperature, but also to equip with a gas spray gun to heat the forging model cavity in time, for instance, the heating is performed once per hour and the die temperature reaches the upper temperature limit, which is also a good method. With these methods, the die temperature can be maintained between 220 and 250 ° C and the forging forming performance is greatly improved.
Selection of Forging Equipment
160T hot die forging press is adopted in the production, the taper core-pulling die base is installed and the core-pulling die is fixed, then the forging production is performed; the 25T mechanical punching machine is used for trimming cutting. The surface can be cleaned by shot blasting machine or vibratory polishing machine.
The DR copper angle valve was trial-produced on the selected equipment by using the above-mentioned forging process, the designed die as well as the forming process parameters. As a result, the forgings defects such as, underfill, folding, false joints, etc, do not occur. The dezincification layer depth is less than 100m after anti-zinc removal performance test and other processing dimensions are in line with customer requirements. It shows that in terms of the difference between the composition and structure of DR copper and C37700 forged brass, the appropriate selection of forging temperature as well as the alloy formation in the β phase region are the primary conditions for DR copper forging; but in this region, the β phase grains are easy to be thick. In order to solve this problem,with a larger forging ratio while forming and crushing the grains which may grow big, it can effectively prevent the coarseness of the β grains and also solve the problem that the DR copper is more difficult to form than the C37700.
CFS Forge is the professional brass forging company for such DR angle valve bodies. Besides, we can also customize other brass forged components, such as air conditioning valve body, brass fittings. If you are looking for a good brass forging supplier in China, pls get in touch with us. We can discuss all the details for your project.