Copper alloys of various compositions have different cr […]
Copper alloys of various compositions have different crystalline characteristics, different casting properties, and different casting process characteristics.
1. Tin bronze: The crystallization is characterized by a large crystallization temperature range and a wide solidification area. In terms of casting properties, the fluidity is poor, it is easy to cause shrinkage, and it is not easy to oxidize. The process is characterized by directional solidification (sequential solidification) of thick-walled parts, and simultaneous solidification of complex thin-walled parts and general thick-walled parts.
2. Aluminum bronze and aluminum brass: The crystallization characteristic is that the crystallization temperature range is small, and it is a layer-by-layer solidification characteristic. In terms of casting properties, it has good fluidity, is easy to form concentrated shrinkage, and is easy to oxidize. The process feature is that the aluminum bronze casting system is bottom-injection and the aluminum brass pouring system is open.
3. Silicon brass: The crystalline feature is between tin bronze and aluminum bronze. The best casting properties (in special brass). The process is characterized by a sequential solidification process, a middle-injection casting system, and a small riser size.
Brass is a copper alloy with zinc as the main additive element. It has a beautiful yellow color and is collectively called brass. The copper-zinc binary alloy is called ordinary brass or simple brass. Ternary or higher brass is called special brass or complex brass. Brass alloys containing less than 36% zinc are composed of solid solution and have good cold workability. For example, brass containing 30% zinc is commonly used to make cartridge cases, commonly known as cartridge brass or seven or three brass. Brass alloys containing between 36% and 42% zinc are composed of solid solution, and the most commonly used is six or four brass with 40% zinc. In order to improve the performance of ordinary brass, other elements are often added, such as aluminum, nickel, manganese, tin, silicon, lead, etc. Aluminum can improve the strength, hardness and corrosion resistance of brass, but reduce plasticity. It is suitable for use as condensing pipes and other corrosion-resistant parts of ships. Tin can improve the strength of brass and the corrosion resistance of seawater, so it is called naval brass, which is used as marine thermal equipment and propeller. Lead improves the cutting performance of brass; this free-cutting brass is often used as a watch part. Brass castings are commonly used to make valves and pipe fittings. The fire hydrant explosion-proof crescent wrench commonly used on ships is made of brass and aluminum.