The development status of brazing materials in China, I know the trouble to answer, and I urgently n

In our country, welding operations need to be licensed, welders are the type of work that belongs to the access category, in the professional qualifications of skilled personnel, only five of the 81 types of work in the access category, welders are one of them, and the actual situation is that most of the industry practitioners are unlicensed operations. With the continuous standardization of technology and the relevant requirements of the industry, more and more people want to take a welding certificate, the advantage of the certificate is still very large, first of all, the salary of the certificate and the non-certificate are very different, often able to reach more than double or higher level. Therefore, the issue of short-term welder training has naturally become a concern for practitioners.

Welding as an industrial "tailor" is a very important means of processing in industrial production, the quality of welding plays a decisive role in the quality of the product, so, what is the future development of welding technology?

Industry outlook. With the development of production, welding is widely used in aerospace, aviation, nuclear industry, shipbuilding, construction and machinery manufacturing and other industrial sectors, in China's economic development, welding technology is an indispensable means of processing. After entering the 21st century, welding is an important part of the manufacturing industry, and the rapid development, so it has brought unprecedented development opportunities to the welding industry.

At present, China consumes 300 million tons of steel every year (about tons of welded structure), and needs about 750,000 welding machines, and the welding industry will continue to grow in the next 8 10 years.

1) Welding method: a) protection state; b) non-protective status; c) Vacuum state; d) the state of the water, etc.;

2) Welding equipment: a) arc welding machine; b) Resistance welding machine; c) Spot welding machine; d) black pole welding machine; e) ** welding machine; Bimetallic composite diffusion (metallurgical) welding machine; Wait;

3) Welding control: a) Automatic welding control; b) Computer welding control; c) Profiling welding control, etc.

The three aspects of welding technology are widely developed.

Brazing is a welding method that uses a metal with a lower melting point than the base metal to penetrate into the weldment seam gap after being heated and melted, and combines it with the base metal to achieve a connection, and the base metal is not melted in this process. Among them, the metal with a lower melting point than the base metal is called brazing metal. In the electronics industry, the tin alloy with a higher melting point is used to connect other individual metals with a higher melting point together, so the welding in electronic products is called tin brazing, and the soldering written in this book is not specifically stated to refer to tin brazing.

The melting point of the soft brazing metal is below 450, and the melting point of the hard brazing metal is above 450. According to the hard brazing metal and soft brazing metal, welding is divided into two categories: hard brazing and soldering. But whether it is hard brazing or soft brazing, the base metal does not melt when they weld the metal.

No pressure is applied to the weldment, which is also the difference between brazing and fusion welding and pressure welding.

Tin brazing is one of the earliest widely used soldering methods for electronic products. Tin brazing has a low melting point, suitable for the connection of electronic materials such as semiconductors, a wide range of applications, simple welding methods, easy to form solder joints, and solder joints have sufficient strength and electrical properties, low cost and simple and convenient operation. The tin brazing process is reversible and easy to desolder.

Tin brazing technology is simple to operate, I feel that children can do a good job, and it is easy to be despised at work, but if there is a problem with a solder joint in electronic products, then it will lead to problems with the whole device, so tin brazing can not be ignored, and tin brazing technology is also a technology that needs to be learned.

Brazing is one of the earliest methods of joining materials used by mankind, and it has been invented to join metals before humans began to use iron. Among the ancient artifacts unearthed in Egypt, there are pipes brazed with silver-copper brazing and talisman boxes connected with gold brazing, which are respectively 5,000 years ago and nearly 4,000 years ago. In the ruins of Pompeii, which was buried by a volcanic eruption in 79 AD, there are remnants of domestic brazed water pipes connected by brazing, and the brazing metal used has sn:

PB=1:2 compositional ratio, similar to the composition of brazing metal used in modern times. China also used tin-lead alloy brazing in the early Warring States period in the 5th century BC, and brazing technology was also widely used in the bronze carriages of the Terracotta Warriors and Horses of Qin Shi Huang.

It was first seen in China when it was recorded in the literature that Ban Gu of the Han Dynasty selected the "Book of Han" when it was recorded in the German brazing: "Hu Tong's tears are blind like tears, and they can also be used by craftsmen today." In 1637, the Ming Dynasty Song Yingxing's scientific and technological masterpiece "Heavenly Creation" has "the Chinese small drill with white copper foam, the large drill is trying to swing the hammer and force it, if the tung juice is combined with silver, it is as hard as a stone."

Today, soldering agents such as jade knife handles, plus silver points, will never take off. Try to spot the solder at the mouth of the round basin in one corner, and the medicine is self-propelling, and it is also strange. This description clearly points out that borax should be used as the brazing agent for copper brazing, and silver brazing can be used as tung resin as the brazing agent, and the caulking behavior of brazing metal is brilliantly described.

Although brazing technology appeared earlier, it has not been greatly developed for a long time. After entering the 20th century, its development also lagged far behind the fusion welding technology. Until the 20th century 30s, on the basis of the development of metallurgical and chemical technology, brazing technology has developed rapidly, and gradually became an independent industrial production account, especially after the Second World War, due to the development of new technologies such as aviation, aerospace, nuclear energy, electronics, etc., the use of new materials and new structural forms, higher requirements for connection technology, brazing technology has therefore received greater attention, rapid development, many new brazing methods have emerged, and their application is becoming more and more extensive.

For example, brazing technology is widely used in the manufacture of various tools for machining, especially cemented carbide tools, drilling tools for drilling and mining, various conduits and containers, water tanks for automobile tractors, heat exchangers of different materials and different structural forms for various purposes, motor parts, and blades and tendons of steam turbines. In light industrial production, brazing technology is widely used in medical devices, metal implants, and musical instruments to household appliances, cooking utensils, and bicycles. For the electronics industry and instrument manufacturing industry, the only feasible link method in a wide range of brazing, such as a large number of metal and ceramic, glass and other non-metal connection problems in the production of components, and in the wiring connection must prevent the damage of heating to the components, all of which rely on brazing technology.

In nuclear power plants and ships, important components such as fuel element positioning frames, heat exchangers, and neutron detectors are also often brazed structures.

2013-2017 China's welding materials industry production and marketing demand and investment ** analysis report shows that in 2010 China's apparent steel consumption of about 100 million tons, China's welding consumables consumption and steel consumption ratio of about about, it can be seen that in 2010 the consumption of welding materials in the virtual 4.65 million tons.

At present, nearly 1,000 welding material manufacturers in China have formed several large enterprise groups based in Tianjin, Zigong, Shanghai, Kunshan, Jinzhou, etc. Due to the continuous expansion of the domestic market, internationally renowned welding material manufacturers have come to China to build factories, using their technical advantages and capital advantages to occupy the high-end welding materials market, and compete directly with domestic enterprises.

China's welding materials industry has a high degree of marketization, and the technical content of ordinary low-grade welding rods and copper-plated welding wires in welding consumables is low, and the entry threshold for false pretense is low, and there has been serious overcapacity in recent years. With the increasing competition in the market, the industry presents a large-scale, collectivized business model, some domestic enterprises through low-price means to encroach on the market at the same time, is speeding up the pace of product structure adjustment, in order to occupy the high-end market.

In 2008, the proportion of China's welding electrodes in welding materials was the proportion of automatic welding consumables solid core and flux-cored welding wires in welding materials, compared with 80% of the values of Japan, South Korea and other industrially developed countries, the proportion of welding consumables consumption with a high degree of automation in China is still very low.

Therefore, in the future, the development strategy of China's welding consumables products will gradually shift, and the high-efficiency and high-quality products with a high degree of automation will gradually replace the manual products, and the manual welding rod products will gradually develop in the direction of high strength, high toughness, low hydrogen and environmental protection, so as to meet the different welding technical requirements of different varieties, different welding structures and different service conditions.

Brazing refers to the welding method in which the brazing metal below the melting point of the weldment and the weldment are heated to the melting temperature of the brazing metal at the same time, and the liquid brazing material is used to fill the gap of the solid workpiece to make the metal connection. During brazing, the oxide film and oil stain on the contact surface of the base metal should be removed first, so as to facilitate the capillary tube to play a role after the brazing metal is melted, and increase the wettability and capillary fluidity of the brazing metal. According to the different melting points of brazing metals, brazing is divided into hard brazing and soft brazing.

The brazing deformation is small, the joints are smooth and beautiful, and it is suitable for welding precise, complex and composed of different materials, such as honeycomb structural panels, turbine blades, tungsten carbide tools and printed circuit boards. Before brazing, the workpiece must be carefully processed and strictly cleaned to remove the oil stain and excessive thickness of the oxide film to ensure the assembly gap of the interface. The clearance is generally required to be between millimeters.

Compared with fusion welding, the base metal does not melt during brazing, only the brazing metal melts; In contrast to pressure welding, no pressure is applied to the weldment during brazing. The weld formed by brazing is called a brazing seam. The filler metal used in brazing is called brazing metal.

Brazing process: The surface-cleaned workpieces are assembled together in a lap pattern, and the brazing metal is placed near the joint gap or between the joint die gaps. When the workpiece and the brazing metal are heated to a temperature slightly higher than the melting point of the brazing metal, the brazing metal melts (the workpiece is not melted), and is sucked in with the help of capillary action and fills the gap between the solid workpiece, the liquid brazing metal and the workpiece metal diffuse and dissolve each other, and the brazing joint is formed after condensation.

1.The essence of fusion welding is the melting and crystallization of metal, similar to the process of small casting; The essence of pressure welding is to squeeze or squeeze out the oxides and other impurities on the joint surface through the plastic deformation of the part to be welded by starvation, so that the pure metal is in close contact, and the atomic spacing between the interfaces reaches the normal stress range and is firmly bonded; The essence of brazing is to use liquid brazing metal to wet the base metal, fill the joint gap, and diffuse with the base metal to realize the connection weldment. Fusion welding is the use of heat to achieve the connection.

Fusion welding: A machining method in which the workpiece to be welded is partially heated until it melts, and after condensation, a weld is formed to connect the components together. Including arc welding, gas welding, electroslag welding, electron beam welding, and soldering; Brazing is a welding method in which the material is combined through the joint action of the wetting of the brazing metal and capillary penetration, and the brazing metal with a lower melting point than the base metal is heated to melting, but the heating temperature is lower than the melting point of the base metal, and the weld is filled with the melted brazing filler, the base metal is wetted and the base metal is diffused with each other to form an integrated welding method.

2.There are two main types of brazing: hard brazing and soldering.

The heating temperature of hard brazing is greater than 450 degrees, the tensile strength is greater than 200 MPa, and silver-based and copper-based brazing metals are often used, which are suitable for occasions with high working stress and high ambient temperature, such as the welding of cemented carbide turning tools and geological drills. The heating temperature of soldering is less than 450 degrees, and the tensile strength is less than 70 MPa, which is suitable for the environment with low stress and low working temperature. For example, tin-based brazing and light welding of circuits.

Brazing During the welding process, a metal material with a lower melting point than the base metal is used as the brazing metal, and the weldment and the brazing metal are heated to a temperature higher than the melting point of the brazing metal and lower than the melting point of the base metal.