There are currently more than 100 kinds of chemical elements known, and about twenty kinds of chemical elements can be encountered in steel materials commonly used in industry. For the special steel series of stainless steel formed by people's long-term struggle with corrosion phenomena, there are more than a dozen of the most commonly used elements. In addition to the basic elemental iron that makes up the steel, it has the greatest influence on the performance and microstructure of stainless steel. The elements are: carbon, chromium, nickel, manganese, silicon, molybdenum, titanium, niobium, titanium, manganese, nitrogen, copper, cobalt, and the like. Among these elements, except for carbon, silicon, and nitrogen, are elements of the transition period in the chemical element periodic table. In fact, stainless steel (stainless steel wire) used in industry is composed of several kinds of elements at the same time. When several elements coexist in the unified body of stainless steel, their influence is much more complicated than when they exist alone. Because in this case not only the role of each element itself, but also the influence of each other, the organization of stainless steel depends on the sum of the influences of various elements. 1-1. The role of chromium in stainless steel: It is decided that there is only one type of element in stainless steel (stainless steel wire), which is chromium, and each type of stainless steel contains a certain amount of chromium. To date, there is no stainless steel that does not contain chromium. The reason why chromium has become the main element determining the performance of stainless steel is that after adding chromium as an alloying element to steel, it promotes the contradictory movement inside it to the development of corrosion resistance. This change can be explained in the following ways: 1Chromium increases the electrode potential of iron-based solid solution 2 chromium absorbs iron electrons to passivate iron Passivation is a phenomenon in which the corrosion resistance of metals and alloys is improved due to the inhibition of the anode reaction. There are many theories that constitute the passivation of metals and alloys, mainly thin film theory, adsorption theory and electronic alignment theory. 1-2. Duality of carbon in stainless steel Carbon is one of the main elements of industrial steel. The properties and organization of steel are largely determined by the content of carbon in steel and its distribution. The influence of carbon in stainless steel (stainless steel wire) is particularly significant. The influence of carbon on the microstructure of stainless steel is mainly manifested in two aspects. On the one hand, carbon is an element that stabilizes austenite, and the degree of action is very large (about 30 times that of nickel). On the other hand, the affinity of carbon and chromium is very high. Large, with chromium - a complex series of carbides. Therefore, from the two aspects of strength and corrosion resistance, the role of carbon in stainless steel is contradictory. Knowing the law of this influence, we can choose different stainless steels with different carbon content from different requirements. For example, the most widely used and most inferior stainless steel in the industry - 0Crl3 ~ 4Cr13, the standard chromium content of the five steel grades is 12-14%, which is to consider the carbon and chromium to form chromium carbide. The purpose of the decision is to combine the carbon and chromium into chromium carbide, the chromium content in the solid solution is not lower than the minimum chromium content of 11.7%. For the five steel grades, the strength and corrosion resistance are also different due to the different carbon content. The corrosion resistance of 0Cr13~2Crl3 steel is better, but the strength is lower than that of 3Crl3 and 4Cr13 steel, which is mostly used to manufacture structural parts. The two steel grades are high in strength due to their high carbon content. They are used to make parts such as springs and knives that require high strength and wear resistance. In order to overcome the intergranular corrosion of 18-8 chrome-nickel stainless steel, the carbon content of the steel can be reduced to less than 0.03%, or an element (titanium or tantalum) having a greater affinity than chromium and carbon can be added to prevent carbonization. Chromium, and when high hardness and wear resistance become the main requirements, we can increase the carbon content of steel while increasing the chromium content, so as to meet the requirements of hardness and wear resistance, Corrosion-resistant function, industrially used as bearing, measuring tool and blade with stainless steel 9Cr18 and 9Cr17MoVCo steel, although the carbon content is as high as 0.85~0.95%, because their chromium content is correspondingly improved, so it still guarantees corrosion resistance. Claim. In general, the carbon content of stainless steels currently used in the industry is relatively low. Most of the carbon content of stainless steel is between 0.1 and 0.4%, and that of acid-resistant steel is mostly 0.1 to 0.2% of carbon. Stainless steel with a carbon content greater than 0.4% accounts for only a small fraction of the total number of steel grades because stainless steel is always resistant to corrosion under most conditions of use. In addition, the lower carbon content is also due to certain process requirements such as ease of soldering and cold deformation. 1-3. The role of nickel in stainless steel (stainless steel wire) is to work with chromium. Concerned about surprises Label: What are the properties and organizational factors of stainless steel wire? Previous: Model and use characteristics of serpentine spring coupling Next: Precautions before purchasing ultrasonic cleaner 304 Stainless Steel Double Pulley Blocks,Marine Pulley Blocks,Yacht Double Pulley Blocks,Stainless Steel Pulley Blocks,Single Pulley Blocks for Sale Jiangsu Dingtian Stainless Steel Products Co., Ltd. , https://www.dingtiancasting.com
(1). Effects and effects of various elements on the properties and microstructure of stainless steel
Nickel is an excellent corrosion-resistant material and an important alloying element for alloy steel. Nickel is an element of austenite in steel, but low-carbon nickel steel requires a pure austenite structure with a nickel content of 24%; and only 27% nickel contains steel resistance in some media. Corrosion performance changes significantly. Therefore, nickel cannot constitute stainless steel alone. However, when nickel and chromium are present in stainless steel, nickel-containing stainless steel has many valuable properties. Based on the above, it is known that the role of nickel as an alloying element in stainless steel is that it changes the microstructure of the high-chromium steel, thereby obtaining some improvement in the corrosion resistance and processability of the stainless steel. 