1 Properties and application of cast aluminum alloy The density of cast aluminum alloy is smaller than that of cast iron and cast steel, but the specific strength is higher. Therefore, the use of aluminum alloy castings under the same load conditions can reduce the weight of the structure. Therefore, aluminum alloy castings have been widely used in the aviation industry and power machinery and transportation machinery manufacturing. Aluminum alloy has good surface gloss and good corrosion resistance in the atmosphere and fresh water, so it has a wide range of uses in the manufacture of civilian utensils. Pure aluminum has good corrosion resistance in oxidizing acid media such as nitric acid and acetic acid, so aluminum castings also have certain uses in the chemical industry. Pure aluminum and aluminum alloys have good thermal conductivity. Heat exchange devices used in chemical production, and parts that require good thermal conductivity on power machinery, such as cylinder heads and pistons of internal combustion engines, are also suitable for aluminum alloys. Manufacturing. Aluminum alloy has good casting properties. Due to its low melting point (pure aluminum has a melting point of 660.230C and the casting temperature of aluminum alloys is generally around 730-750oC), casting methods such as metal molds and pressure casting can be widely used to improve the inherent quality, dimensional accuracy and surface of casting Finish and production efficiency. Due to the large latent heat of solidification, under the same weight conditions, the solidification process time of aluminum alloy is much longer than that of cast steel and cast iron, and the fluidity is good, which is conducive to casting thin-walled and complicated structures. The classification of cast aluminum associations and grades of aluminum alloys are divided into two categories according to different processing methods, namely pressure-processed aluminum alloys and cast aluminum alloys (represented by YL and ZL, respectively). In the cast aluminum alloy, it is divided into four series according to the different alloying elements that are mainly added, namely cast aluminum silicon alloy, aluminum copper alloy, cast aluminum magnesium alloy, and cast lead zinc alloy (respectively ZL1XX, ZL2XX, ZL3XX and ZL4XX), in each series is divided into several grades according to the different chemical composition and performance. Copper-based alloys are widely used in shipbuilding and chemical industries due to their good corrosion resistance to freshwater, seawater and certain chemical solutions. Copper-based alloys also have good thermal conductivity and abrasion resistance, so they are often used in the manufacture of sliding bearing bushings that bear heavy loads and run at high speed on various machines. Cast copper alloys fall into two broad categories, brass and bronze. Brass is a copper alloy with zinc as the main alloying element. Manganese brass, aluminum brass, silicon brass, lead brass, etc. are formed in the cast brass due to the addition of other alloying elements. In copper alloys, zinc is not used as the main element and is collectively called bronze, such as tin bronze, aluminum bronze, lead bronze, beryllium bronze, and so on. National standards stipulate that there are 9 types of cast copper alloys, with 29 brands in total. 3 Other non-ferrous alloys In addition to cast aluminum alloys and cast copper alloys, there are many other types of non-ferrous alloys. Among them, cast magnesium alloy, cast titanium alloy and cast zinc alloy are more commonly used. Magnesium alloys and titanium alloys are mostly used in the aviation industry because of their high specific strength. Among them, titanium alloy also has strong corrosion resistance to a variety of corrosive media, so it is also used to manufacture castings that undergo corrosion in petrochemical equipment. Zinc alloys have relatively high strength and excellent casting properties, so they are widely used in the manufacture of thin-walled and complex-structured castings. In terms of casting methods, in addition to sand CNC machining https://www.bronzecast.net/ casting, copper alloys and other non-ferrous alloys are also widely used in various special casting methods such as metal casting, centrifugal casting, low-pressure casting, and graphite casting. In copper alloy casting, a metal mold casting method is used to accelerate the solidification of the alloy, which has an important role in improving the quality of castings and reducing casting defects. Metal mold casting can subdivide grains (especially for aluminum bronze and manganese brass), reduce porosity, improve the mechanical properties and air tightness of the alloy (especially important for tin bronze), in high-lead copper alloys such as lead bronze, Metal mold (and water-cooled metal mold) casting can prevent segregation of copper components. In addition, since there are many cylindrical parts (bearings, bushings) in copper alloy castings, centrifugal casting methods are often used. In addition, large-scale copper castings (such as large marine propellers) can also use low-pressure casting methods to increase the density of the alloy and reduce the inclusions produced during the casting process. Some copper alloys (such as lead brass) can also be pressure cast. Due to the poor casting properties of magnesium alloys, especially the possibility of thermal cracking, most of the magnesium alloy castings are still made by sand casting. Only a small part of simple castings can be cast with metal molds. The pressure casting method is rarely used in magnesium alloy casting. Zinc alloy has good casting performance, strong filling mold ability, and does not cause hot cracking, so it is especially suitable for metal mold and pressure casting. Pressure casting methods are commonly used in mass production to produce thin-walled and complex zinc alloy castings. Titanium alloy is extremely chemically active. During the casting process, the titanium liquid interacts with most casting materials (including various molding sands and steels), causing the casting to be contaminated. Therefore, only special casting materials ( Such as hafnium oxide or graphite). 4 The melting and smelting process of casting nonferrous alloys has a great impact on the properties and defects of nonferrous alloy castings. Most non-ferrous alloys are prone to pores and inclusions, especially titanium alloys, aluminum alloys, magnesium alloys and some copper alloys. The general melting process is: 1) According to the alloy grade specified in the technical requirements of the casting, the chemical composition range of the alloy can be found out, and the chemical composition can be selected from it; 2) The calculation of the ingredients is based on the burn-out rate and composition requirements of the element, Calculate the amount of various charge, and select the charge. If the charge is contaminated, it needs to be processed to ensure that all the charge is clean and rust-free, and pre-heated before feeding; 3) Check and prepare chemical appliances, apply paint, and pre-heat to prevent gas, inclusions and harmful Elemental pollution; 4) Feeding. The general charging sequence is: reflow material, intermediate alloy and metal material, low melting point and easily oxidizable metal material, such as magnesium, added after the furnace material is melted; 5) In order to reduce the suction and oxidation pollution of the alloy liquid, it should be melted as soon as possible to prevent Overheating, as required, some alloy liquids must be protected by a covering agent; 6) After the furnace charge is melted, refining treatment is performed to purify the alloy liquid and the refining effect is inspected; 7) As required, it undergoes modification treatment and subdivided tissue treatment In order to improve the performance and check the treatment effect; 8) adjust the temperature and perform pouring. Some alloys are stirred before pouring to prevent specific gravity segregation.
1 Properties and application of cast aluminum alloy The density of cast aluminum alloy is smaller than that of cast iron and cast steel, but the specific strength is higher. Therefore, the use of aluminum alloy castings under the same load conditions can reduce the weight of the structure. Therefore, aluminum alloy castings have been widely used in the aviation industry and power machinery and transportation machinery manufacturing. Aluminum alloy has good surface gloss and good corrosion resistance in the atmosphere and fresh water, so it has a wide range of uses in the manufacture of civilian utensils. Pure aluminum has good corrosion resistance in oxidizing acid media such as nitric acid and acetic acid, so aluminum castings also have certain uses in the chemical industry. Pure aluminum and aluminum alloys have good thermal conductivity. Heat exchange devices used in chemical production, and parts that require good thermal conductivity on power machinery, such as cylinder heads and pistons of internal combustion engines, are also suitable for aluminum alloys. Manufacturing. Aluminum alloy has good casting properties. Due to its low melting point (pure aluminum has a melting point of 660.230C and the casting temperature of aluminum alloys is generally around 730-750oC), casting methods such as metal molds and pressure casting can be widely used to improve the inherent quality, dimensional accuracy and surface of casting Finish and production efficiency. Due to the large latent heat of solidification, under the same weight conditions, the solidification process time of aluminum alloy is much longer than that of cast steel and cast iron, and the fluidity is good, which is conducive to casting thin-walled and complicated structures. The classification of cast aluminum associations and grades of aluminum alloys are divided into two categories according to different processing methods, namely pressure-processed aluminum alloys and cast aluminum alloys (represented by YL and ZL, respectively). In the cast aluminum alloy, it is divided into four series according to the different alloying elements that are mainly added, namely cast aluminum silicon alloy, aluminum copper alloy, cast aluminum magnesium alloy, and cast lead zinc alloy (respectively ZL1XX, ZL2XX, ZL3XX and ZL4XX), in each series is divided into several grades according to the different chemical composition and performance. Copper-based alloys are widely used in shipbuilding and chemical industries due to their good corrosion resistance to freshwater, seawater and certain chemical solutions. Copper-based alloys also have good thermal conductivity and abrasion resistance, so they are often used in the manufacture of sliding bearing bushings that bear heavy loads and run at high speed on various machines. Cast copper alloys fall into two broad categories, brass and bronze. Brass is a copper alloy with zinc as the main alloying element. Manganese brass, aluminum brass, silicon brass, lead brass, etc. are formed in the cast brass due to the addition of other alloying elements. In copper alloys, zinc is not used as the main element and is collectively called bronze, such as tin bronze, aluminum bronze, lead bronze, beryllium bronze, and so on. National standards stipulate that there are 9 types of cast copper alloys, with 29 brands in total. 3 Other non-ferrous alloys In addition to cast aluminum alloys and cast copper alloys, there are many other types of non-ferrous alloys. Among them, cast magnesium alloy, cast titanium alloy and cast zinc alloy are more commonly used. Magnesium alloys and titanium alloys are mostly used in the aviation industry because of their high specific strength. Among them, titanium alloy also has strong corrosion resistance to a variety of corrosive media, so it is also used to manufacture castings that undergo corrosion in petrochemical equipment. Zinc alloys have relatively high strength and excellent casting properties, so they are widely used in the manufacture of thin-walled and complex-structured castings. In terms of casting methods, in addition to sand CNC machining https://www.bronzecast.net/ casting, copper alloys and other non-ferrous alloys are also widely used in various special casting methods such as metal casting, centrifugal casting, low-pressure casting, and graphite casting. In copper alloy casting, a metal mold casting method is used to accelerate the solidification of the alloy, which has an important role in improving the quality of castings and reducing casting defects. Metal mold casting can subdivide grains (especially for aluminum bronze and manganese brass), reduce porosity, improve the mechanical properties and air tightness of the alloy (especially important for tin bronze), in high-lead copper alloys such as lead bronze, Metal mold (and water-cooled metal mold) casting can prevent segregation of copper components. In addition, since there are many cylindrical parts (bearings, bushings) in copper alloy castings, centrifugal casting methods are often used. In addition, large-scale copper castings (such as large marine propellers) can also use low-pressure casting methods to increase the density of the alloy and reduce the inclusions produced during the casting process. Some copper alloys (such as lead brass) can also be pressure cast. Due to the poor casting properties of magnesium alloys, especially the possibility of thermal cracking, most of the magnesium alloy castings are still made by sand casting. Only a small part of simple castings can be cast with metal molds. The pressure casting method is rarely used in magnesium alloy casting. Zinc alloy has good casting performance, strong filling mold ability, and does not cause hot cracking, so it is especially suitable for metal mold and pressure casting. Pressure casting methods are commonly used in mass production to produce thin-walled and complex zinc alloy castings. Titanium alloy is extremely chemically active. During the casting process, the titanium liquid interacts with most casting materials (including various molding sands and steels), causing the casting to be contaminated. Therefore, only special casting materials ( Such as hafnium oxide or graphite). 4 The melting and smelting process of casting nonferrous alloys has a great impact on the properties and defects of nonferrous alloy castings. Most non-ferrous alloys are prone to pores and inclusions, especially titanium alloys, aluminum alloys, magnesium alloys and some copper alloys. The general melting process is: 1) According to the alloy grade specified in the technical requirements of the casting, the chemical composition range of the alloy can be found out, and the chemical composition can be selected from it; 2) The calculation of the ingredients is based on the burn-out rate and composition requirements of the element, Calculate the amount of various charge, and select the charge. If the charge is contaminated, it needs to be processed to ensure that all the charge is clean and rust-free, and pre-heated before feeding; 3) Check and prepare chemical appliances, apply paint, and pre-heat to prevent gas, inclusions and harmful Elemental pollution; 4) Feeding. The general charging sequence is: reflow material, intermediate alloy and metal material, low melting point and easily oxidizable metal material, such as magnesium, added after the furnace material is melted; 5) In order to reduce the suction and oxidation pollution of the alloy liquid, it should be melted as soon as possible to prevent Overheating, as required, some alloy liquids must be protected by a covering agent; 6) After the furnace charge is melted, refining treatment is performed to purify the alloy liquid and the refining effect is inspected; 7) As required, it undergoes modification treatment and subdivided tissue treatment In order to improve the performance and check the treatment effect; 8) adjust the temperature and perform pouring. Some alloys are stirred before pouring to prevent specific gravity segregation.
