A nitrogen-containing manganese metal smelting for multi-component alloy, the nitrogen can improve the strength of steel and plastic, expanded nitrogen is part of the austenite region. Accordingly, the nitrogen may be substituted with manganese steel in many grades of nickel, austenitic - ferritic stainless steel acid (1Cr18MnlONi5Mo3N) and Section nickel austenitic - ferritic stainless steel acid (OCr17Mn14Mo2N) and the like, can be Nickel is more than 60%. Nickel is a rare heavy metal element with limited resources and high price. It has obvious economic value with metal manganese or manganese nitride, and has good market prospects. In the Mn-N system, a solid solution exists in addition to the compound, and it is determined that the solubility of nitrogen in a manganese is about 0.15%, and the solubility in ?-Mn is much larger. When the content of nitrogen in the solid solution is 2.31%~3.26%, the matrix of the solid solution is Mn 4 N, and when the nitrogen content is 6.52%~9.22%, the matrix of the solid solution is Mn 4 N and Mn 5 N 2 , and the nitrogen content is 9.22%. At the time, nitrogen exists in the form of the compound Mn 5 N 2 . Garden Tractor,Compact Tractors,Mini Tractor,Yard Tractors Hunan Nongyou Machinery Group CO.,LTD , https://www.ricemill.nl
Nitrogen is a diatomic molecule. The nitrogen atom is formed by the combination of three pairs of electrons, forming three covalent bonds with a bond energy of up to 949.571 J/mol, which is much larger than the bond energy of other diatomic molecules (such as H 2 and O 2 ). Therefore, the structure of the nitrogen molecule is very stable. The chemical properties are inactive and it is difficult to chemically react with other substances, but at high temperatures, sufficient energy is obtained to cause the covalent bond to break. This can react with certain metals and non-metals to form nitrides.
The main role of nitrogen in steel is solid solution strengthening and strengthening precipitation; forming and stabilizing austenite structure, which acts ten times more than nickel; improving the macrostructure of high chromium and high chromium nickel steel, making it dense and firm, and improving strength; It combines with alloying elements such as Cr, Al, V, Ti in steel to form nitrides, which improves the strength, hardness, wear resistance and corrosion resistance of steel.
For low-carbon high-chromium steel with coarse grains, after adding appropriate nitrogen, the formation of a small amount of austenite and the presence of many fine nitride sites will limit the growth of ferrite grains, thereby obtaining fine-grained structure. It is beneficial to improve the impact toughness of steel and improve its welding performance.
Nitrogen-based nickel can save expensive metal nickel, which can greatly reduce production costs. Based on the above effects of nitrogen-containing manganese, it is often necessary to simultaneously add some alloys. When added alone, manganese is highly oxidizable. Nitrogen is not easy to be added due to its extremely low density. It is often added at the same time when smelting some alloys, and the utilization rate of manganese nitrogen is high.
From the thermodynamic data and the equilibrium phase diagram of Mn-N system under normal pressure, it can be seen that pure manganese reacts with nitrogen under normal pressure to form Mn 4 N, Mn 5 N 2 , Mn 3 N 2 and Mn 2 N. The relationship between the standard free energy of formation of nitride and temperature is shown in Figure 1. As can be seen from Fig. 1, the ΔG value of the formation of manganese nitride in a certain temperature range is much smaller than 0, so that manganese nitride is easily formed and has good stability. It can be seen from the binary phase diagram of Mn-N (Fig. 2) that the solubility of nitrogen in FeMn increases with the increase of manganese content, and it can be seen that the effect of metal manganese nitridation should be better than that of iron. 
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The standard free energy (25 ° C) and Mn-N binary phase diagram of manganese nitride (shown in Figure 2).
Nitriding process: There are three main production processes of manganese nitride, which use nitrogen or solid nitrogen-containing substances to nitridify liquid metal; nitriding powdery solid metal powder; using metal powder and nitrogen-containing substance (cyanamide) and sticking The joint is pressed together to nitrite.
When the liquid metal manganese is nitrided, if the nitrogen pressure is constant, the solubility of nitrogen in the alloy decreases as the temperature increases.
When PN 2 = 105 Pa, the solubility of liquid metal manganese at N 2 at 1300 ° C was 2.5%, and at 1500 ° C was 1.6%.
The solubility of nitrogen in liquid metal manganese increases with increasing nitrogen pressure.
Russian scholars have suggested nitriding in a furnace with a nitrogen pressure of (8~18) x 10 5 Pa.
A disadvantage of the liquid metal nitriding process is that the nitrogen content is very low.
Nitriding of the solid metal powder can result in a metal powder or compact having a high nitrogen content. However, the rate of nitriding is determined by the rate of diffusion of nitrogen. Therefore, the nitriding rate is slow. In addition, the powdered metal obtained by this method has a small density, nitrogen is not easily absorbed by the molten steel, and only 60% to 80% of the nitrogen is absorbed. A remelted method can be used to prepare a dense metal manganese having a high nitrogen content and then added to the molten steel.
In the 1970s, the former Soviet Union Institute of Black Metallurgy and the Zaporosh Ferroalloy Plant used metal manganese powder to produce nitrogen-containing manganese. The process is as follows:
The manganese metal powder is placed in a cylindrical electric furnace for nitriding. The angle between the cylinder and the horizontal line is three degrees, the powder accounts for 7% to 9% of the volume of the cylinder, the nitrogen is preheated in advance, the manganese powder contains 5% to 6% of nitrogen, and the power consumption of the product is 1270 kW·h/t. About 500m 3 /t.
China's Chongqing University and Chongqing Triangle Beach Manganese Company have studied the production of manganese nitride by solid state nitriding. The process is to obtain manganese nitride by nitriding manganese powder with nitrogen generated by decomposition of ammonia gas at high temperature. The experiment has studied the factors such as particle size, nitriding time and nitriding speed of manganese powder. The test results show that the particle size of manganese metal powder has a great influence on the nitriding process. When the temperature is higher than 600 °C, manganese nitride containing 6.90% of N 2 can be obtained.
At present, the production of manganese nitride at home and abroad is mostly produced by solid state nitriding of metal powder. South Africa is the world's leading producer of manganese nitride.