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Many mechanical parts and engineering components work under alternating load. Under the action of alternating load, although the stress level is lower than the yield limit of the material, after a long time of repeated stress cycle, sudden brittle fracture will also occur. This phenomenon is called fatigue of metal materials. The characteristics of fatigue fracture of metal materials are:  (1) The load stress is alternating;  (2) The action time of load is long;  (3) The fracture occurs instantaneously;  (4) Both plastic and brittle materials are brittle in the fatigue fracture zone. Therefore, fatigue fracture is the most common and…

Metal materials refer to metal elements or materials with metal characteristics mainly composed of metal elements. Including pure metals, alloys, metal materials, intermetallic compounds and special metal materials. (Note: metal oxides (such as alumina) are not metal materials) 1. Meaning: The development of metal materials is closely related to the progress of human civilization. After the stone age, the bronze age and iron age are marked by the application of metal materials. In modern times, a wide variety of metal materials have become an important material basis for the development of human society. 2. Type: Metal materials are usually divided…

The characteristics of chemical reactions between metals and other substances are called the chemical properties of metals. In practical application, the corrosion resistance and oxidation resistance of metals (also known as oxidation resistance, which refers to the resistance or stability of metals to oxidation at high temperature) and the influence of compounds formed between different metals and between metals and non metals on mechanical properties are mainly considered. In the chemical properties of metals, especially the corrosion resistance is of great significance to the corrosion fatigue damage of metals.

1. Yield point（ σ s) When the stress of steel or sample exceeds the elastic limit during tension, even if the stress is no longer increased, the steel or sample continues to have obvious plastic deformation. This phenomenon is called yield, and the minimum stress value when yield phenomenon occurs is the yield point. If PS is the external force at the yield point s and fo is the cross-sectional area of the sample, then the yield point σ s =Ps/Fo(MPa) 2. Yield strength（ σ 0.2) The yield point of some metal materials is not obvious, so it is difficult…

According to the analysis of magnesium alloy, 6063 alloy has excellent processability and weldability, which is mainly related to the extrusion and polishing of magnesium alloy.6063 alloy is widely used in building profiles, irrigation pipes, pipes, rods and profiles for vehicles, platforms, furniture, elevators and fences.

Explanation of common aluminum alloy properties (I): 2024-LY12 aluminum alloy 2024 (LY12) is a typical hard aluminum alloy in aluminum copper magnesium system. Its composition is reasonable and its comprehensive properties are good. Many countries produce this alloy, which is the largest amount of duralumin. The alloy is characterized by high strength and certain heat resistance. It can be used as working parts below 150 ° C. When the temperature is higher than 125 ° C, the strength of 2024 alloy is higher than that of 7075 alloy. The formability is better in thermal state, annealing and new quenching state,…

For the car body, our direct feeling is "iron wrapped meat". Therefore, we take it for granted that the car shell is made of steel. In fact, with the continuous development of materials and manufacturing technology, more and more new materials have also joined the base camp of automobile manufacturing. Today, let's see what materials can be used for automobile body except steel? 1. Already popular - all aluminum alloy Audi's ASF (Audi space frame) is one of the pioneers of all aluminum alloy body. It has a history of 23 years, and a total of 9 Audi have been…

With the development of industrial society and the continuous improvement of living standards, people's demand for living products and desire for innovation are also growing day by day. Therefore, there are processing enterprises, which are mainly satisfied that with the development of science and technology, people increasingly create new products, so as to serve enterprises in different fields such as design, development and manufacturing, develop new products or improve existing products, and design new products for them, give full cooperation and support in model making and model making, create mutual value and achieve win-win results. The products of each enterprise…

There are various classification methods for steel, and the main methods are as follows: 1. Classification by quality  (1) Ordinary steel (P ≤ 0.045%, s ≤ 0.050%)  (2) High quality steel (P and s ≤ 0.035%)  (3) High quality steel (P ≤ 0.035%, s ≤ 0.030%) 2. Classification by chemical composition  (1) Carbon steel: A. low carbon steel (C ≤ 0.25%); b. Medium carbon steel (C ≤ 0.25 ~ 0.60%); c. High carbon steel (C ≤ 0.60%).  (2) Alloy steel: A. low alloy steel (total content of alloy elements ≤ 5%); b. Medium alloy steel (total alloy element content >…

Titanium is a polycrystalline metal. Below 882 ℃, it is a crystal form. Its atomic structure is a close packed hexagonal lattice. From 882 ℃ to the melting point, it is B crystal form and a body centered cubic lattice. Industrial pure titanium presents a phase in the metallographic structure. If the annealing is complete, it is an equiaxed single lattice with basically equal size. Due to the existence of impurities, there is also a small amount of B phase in industrial pure titanium. It is basically distributed along the grain boundary. Industrial pure titanium according to GB / t3620…