Effect of Chromium and Silicon Contents on Microstructure and Corrosion Resistance of Nickel Base Superalloy

Influence of No. Content Silicon Content on Microstructure and Corrosion Resistance of Nickel Base Superalloy Chen. Sun Jiashu. Schenson, Zhao Runyi Department of Materials Science and Engineering, Tianjin Institute of Technology. Tianjin 300,191 X-ray diffraction combined with the method of comprehensive minute hand, studied the effect of content on the structure and phase composition of the test material. The result is clear. When the content is suitable, the alloy can achieve the soap reinforcement of carbide boride and silicide. The number of phases in the alloy is evenly distributed, and the hardness and corrosion resistance are high. Substituting 85 or less for niobium-based alloys. Has a broad application prospects.

Nickel-base superalloys are high temperature structural materials widely used in industry. Their working environment determines that these components are often subjected to high-temperature abrasive erosion damage, and their service life is reduced 2.

If the surface of these parts can be coated with a coating with a higher layer performance than the substrate, it will have the excellent properties of heat resistance, high temperature resistance, oxidation resistance, heat resistance and corrosion resistance, which will inevitably bring great economic benefits. In recent years, intermetallic compound-reinforced metal-based complexes have become a hot topic in this area due to their excellent properties. Some of the errors 34 and silicide 5 have been reported, and the latter is considered to be the most promising new generation of high-temperature structures. material. In this study, the method of plasma spray welding was used to make the test alloy and the substrate reach good and hot corrosion resistance. The influence of the content of 03 on the formation of the ceramide and even the overall performance of the alloy was analyzed, and the best alloy distribution ratio was obtained. Industrial production provides the basis.

1 Material composition design and experimental methods Fund project Taijin City Science and Technology Foundation grant 38021.1 Material composition design Multi-element alloying is an effective way to improve the heat resistance, wear resistance and corrosion resistance of gold. In consideration of the fact that alloying elements are relatively cheap and easy to form paleosols with nickel and do not form low-melting co-products to form a stable strengthening phase, the 3-claw 255 guan 4 alloys were designed. The towel chromium has several functions, which can dissolve into the solid solution of the alloy to become an alloy, a matrix, and can form a first-phase reinforcing matrix with carbon and silicon and other elements, plus the abrasion resistance of the spray-welding layer, and can be oxidized and corroded at the same time. The formation of a dense protective film in the environment significantly improves the material's resistance to thermal and thermal fatigue. In addition, the main material choice for adding silicon is to form intermetallic strengthening phases and promote the formation of carbides. Makes the alloy multi-strengthened. Simultaneously. Silicon also resists high temperature oxidation and corrosion of beneficial elements. Judging from the results of its own research, the yttrium's yttrium is generally present in the near six gold alloys and the oxide film density. Improve the alloy's resistance to temperature oxidation and hot corrosion. 1.2 Test methods and equipment Gold chrome, iron 201; 1; 1 carbon ferrochrome and other raw materials.

According to the material design ratio, smelting in the atmosphere in a high-frequency induction furnace, nitrogen atomization powder. A 5 inmj6JV layer was used as a plasma spray welding sample on a plasma jet welding machine. And using optical microscopy scanning electron microscopy analysis of the energy spectrum 03, ray decay, etc. Analysis and study of the experimental structure of the village material and phase composition of hot corrosion test to spray welding alloy wire is called a 12-section specimen cut. And coated with 4 paste 1 and 3, 4 mixed salt, to be dry after the heat preservation at 85, remove the residual salt after washing to observe and compare.

2 Test results and analysis 2.1 The morphology and phase analysis of the tissue were analyzed by scanning electron microscopy (SEM) and the corresponding energy spectrum analysis results. As you can see, with the increase in the content of 31, the number of phases in the tissue has increased significantly, and the amount of phase 4 up to 4 samples has reached 60 or more. 5 Faced with the organization of the alloy was analyzed.

From 1 to 1 sample, the sample was organized into typical cell dendrites. The combined energy spectrum analysis revealed that the dark black matrix was identified as a 51-based nickel-based 7 solid solution. Considering that the alloy has a higher content of boron in the grain boundary, combined with the gold phase spectrum analysis, the 8-point bar and small bone-like structure should be typical elements. 2 The amount of 7 solid solution in the sample was significantly reduced by 2 and increased from the solid solution 1 content of the composition. 1. The decrease in the content indicates that the formula is also formed in addition to the solid solution. The phase and carbides of the Huali Chemicals. 1 10 medium gold + promote carbide formation child Thailand, broken products should be 1 for. The type, type, bamboo frame, this phase is generally found in alloys with higher content, the content of the alloy is high, indicating that silicon is still dissolved in the matrix 1 sample.纟 形;morphology 80.134 test 忭 organizational shape groove 8,144 sample matrix energy spectrum, silicide has not yet formed. The gold organization 2 is due to the high content of alloys and the significant increase in the number of carbides. The amount is obvious, plus, 7 the amount of solid solution continues to decrease 4, so the peak intensity of nickel in 5,3 decreased, and the content of 31 is not high, especially the peak value of 3 is significantly lower than the sample.

It can be concluded that silicide has been formed in the 4 alloy.

The massive phase is a remuneration compound. The combination of the rules of the dot rule and the ray diffraction analysis shows that the silicides are mainly 0, office, and heart 27. According to data7, it is reported that type 1 intermetallic compounds are densely packed. 1. It needs to be formed under a large electron concentration. 4 The content has reached 8 so that the electron concentration of the alloy is calculated to exceed that of the formation of 0 phase, while 2 gas is formed.

From the above analysis, it can be seen that the low silicon content of the urethane formed in the nickel-base alloy is about 8 or so. It is still to be studied and improved whether the high silicon content of the Shi Gao is more beneficial.

The macro-hardness of the alloys listed in the column Guang-you 1. With the increase in the number and type of the first phase, the hardness of the alloy rises significantly, and the results are better than the above tissue analysis.

Sample No. Hardness value 2.2 Anti-molten salt Hot corrosion performance Hot corrosion is a form of accelerated oxidative corrosion due to molten salt deposition. That is, the protective oxide film formed by oxidation in the air dissolves in the molten salt, accelerating the corrosion process of the alloy.

From the test alloy, the surface morphology of the 祚1 specimen after molten salt corrosion was thinned. The erosion process is severe, strict 1. Scanning electron microscope analysis Court 64 also clothing Ming. The corrosion boundary is uneven and the low-chromium 7 solid solution can be easily eroded by the molten salt. With the content of the alloy, plus, theoretically speaking, when the corrosion resistance is more than 10, the corrosion resistance is indeed observed in the test, and the corrosion boundary of 1 41 = is relatively neat, especially after washing out the crucible, and then seeing the macroscopic comparison. Dense corrosion layer. In the case of high-temperature hot corrosion, surface selective oxidation of the alloy occurs first, and the surface oxidation of the alloy containing a lower amount of chromium is mainly positive 0, followed by an acid fusion reaction between 0 and 23, 4, which is a kind of sustainable disaster. Sexual reactions continue to exacerbate the progress of oxidative corrosion. When the content of the alloy is high, the surface and the skin are mainly 12, 3 . In addition, the alloy 5 is also a beneficial element for high temperature corrosion, which can promote the formation of 203, but also in 03 A 5:02 interlayer is formed between the film and the metal. Absorption of vacancies increases the density of the oxide film and weakens the corrosion. But because of the heart in the molten salt. Adding test skins should be done. Reduce the strength. At the same time, it is also possible to form low-melting-point volatile metal chlorides, such as 2, to increase the porosity of the oxide film. Therefore, the molten salt corrosion degree of several test materials is higher than that of fire. However, the corrosion resistance of molten salt containing high alloys is significantly better than that of other species1.

3 Conclusion 1 The widest chromium content of the wide sample is only the solid solution strengthening and grain boundary, and 1 material strengthening. The macro hardness is low.

Co-reinforced, hardness increased 231 =.

The silicon content of the silicide formed in the nickel-based alloy is around 8 so that 4 = the alloy sample is carbide-based and the silicide compound is strengthened, and the macro-hardness of the alloy is high.

7 Zhu Ri Zhang. Lu Yexuan. Hot steel and high temperature six gold 1. Beijing Chemical Industry Press. 1996.

Tianjin Institute of Technology Polytechnic Industry Group was awarded the Outstanding Contribution Award of the Tianjin Science and Technology City in the end of October 1999. The Tianjin Municipal Government held a grand meeting, and it also carried out key projects that have made outstanding contributions to the economic development of the city in recent years. Chang. Tianjin University of Technology's affiliated Ricoh 1 industry set, limited to the company's own research and development of high-quality acid, wave city government awarded the first session of science and technology to make outstanding contribution awards and awards to the group president Li Shaowu researcher headed by the project research and development team bonus of 100,000 yuan.