Bronze with tin as the main alloying element. Tin content is generally between 3-14%, mainly used to make elastic components and wear - resistant parts. The tin content of deformed tin bronze is not more than 8%, and sometimes phosphorus, lead, zinc and other elements are added. Phosphorus is a good deoxidizer and can also improve fluidity and wear resistance. The machinability and wear resistance of tin bronze can be improved by adding lead, and the casting performance can be improved by adding zinc. This alloy has high mechanical properties, wear reduction properties and corrosion resistance, free cutting, good brazing and welding properties, small shrinkage coefficient, no magnetism. Bronze bushing, axle sleeve, antimagnetic element and other coatings can be prepared by wire flame spraying and arc spraying. Size 1.6 mm, 2.3 mm Ф Ф. With high strength, corrosion resistance and excellent casting performance, it has been widely used in various industrial sectors for a long time.
Copper was made and used as early as 3000 BC. But things made of refined copper were too soft, bent easily, and soon became dull. Then it was discovered that tin was mixed with copper to make a copper-tin alloy called bronze. Bronze ware melting and production is much easier than pure copper, hard than pure copper (if the hardness value of tin is 5, so the hardness of copper is 30, and the hardness of bronze is 100~150), the history called this period as the Bronze Age.
The rites of zhou of the warring states period in China book, dong guan, Zhou people "summed up the experience of smelting bronze, bronze casting various objects with copper and tin of different scale:" gold six qi (prescription). Six cent of its gold (copper) and tin in one, that is, the ding of the qi; Five percent of its gold and tin in one, that the axe jins qi; Four of its gold and tin in one, that is, the uniform of the halberd; Three of its gold and tin in one, that is the great edge of the qi; Five percent of its gold and tin in two, that is to cut the arrow (arrow) qi; A half of gold and tin is called a mirror, which is a mirror used to gather light and fire." This shows that more than 3,000 years ago, the working people of our country he realized that the performance required by different bronze ware for different purposes is different, and the proportion of metal composition used for casting bronze ware should also be different.
Because bronze is hard and fusible, it is well cast and stable in the air, so that it did not lose its usefulness even in the iron age after the age of bronze. For example, in about 280 BC, the bronze sun god standing in the port of rhodes on the island of rhodes in the middle of the Aegean sea in Europe was 46 meters tall and its fingers were higher than the height of a man.
In addition to 3%~14% tin, tin bronze is often added with phosphorus, zinc, lead and other elements. It is the earliest alloy used by human beings and has been used for about 4000 years. It is corrosion-resistant, wear-resistant, has better mechanical properties and technological properties, and can be well welded and brazed, impact without spark. It is divided into processed tin bronze and cast tin bronze. Tin content of tin bronze used for pressure machining is less than 6%~7%, and that of cast tin bronze is 10%~14%. Common brands include qsn4-3, qsn4.4-2.5, qsn7-o.2, ZQSn10, zqsn5-2-5, zqsn6-6-3, etc. Tin bronze is a nonferrous metal alloy with the smallest shrinkage rate, which can be used to produce castings with complex shapes, clear Outlines and low air tightness requirements. Tin bronze is very resistant to corrosion in atmosphere, sea water, fresh water and steam, and is widely used in steam boilers and Marine ship parts. Phosphorous tin bronze has good mechanical properties and can be used as wear-resisting and elastic parts of high precision working machine. Lead tin bronze is often used for wear - resistant parts and sliding bearings. Zinc tin bronze can be used for air - tight castings.
The solidification range of tin bronze is large and the dendrite segregation is serious. During solidification, it is difficult to form concentrated shrinkage city and the volume shrinkage is small. The reverse segregation of tin is easy to occur in the ingot. In serious cases, white spots (8 phase precipitates) can be seen on the surface of the ingot, and even tin-rich particles can appear, which are generally called tinsweat. The degree of reverse segregation can be reduced by improving the casting method and technological conditions. In liquid alloy, tin is easy to grow into the inclusion SnO2 which is hard and brittle. Sufficient deoxidation is required in smelting to prevent the decrease of mechanical properties of the alloy caused by the inclusion. It has little sensitivity to overheat and gas and can weld and braze well. No spark occurs during impact, no magnetism, cold resistance, and has extremely high wear resistance.
Industrial tin bronze tin bronze is an important copper alloy used in industry. In order to improve its casting, mechanical properties and wear resistance, as well as to se tin, phosphorus, zinc, lead and other alloying elements were added to tin bronze. Therefore, tin bronze can be divided into three categories: tin phosphor bronze, tin zinc bronze and tin zinc lead.
Folded tin-phosphor bronze
Phosphorus is a good deoxidizer for copper alloy, which can increase the fluidity of the alloy, improve the technology and mechanical properties of tin bronze, but increase the degree of reverse segregation.
The limiting solubility of phosphorus in tin bronze is 0.15%, and too much of it will form a+ +Cu ternarly eutectic with a melting point of 628℃. It is easy to produce hot brittleness during hot rolling and can only be processed cold. Therefore, the phosphorus content in the deformed tin bronze should not be more than 0.5%, and the phosphorus should be less than 0.25% during the hot processing.
Phosphorous tin bronze is a famous elastic material. It is necessary to control the grain size before cold processing and low temperature annealing after processing. The strength, elastic modulus and fatigue strength of fine grain machined material are higher than that of coarse grain machined material, but the plasticity is lower. The annealing hardening effect can be produced when the cold processed material is annealed at a low temperature of 200~260℃ for 1~2h, which can further improve the strength, plasticity, elastic limit and elastic modulus of the product and increase its elastic stability.