1. Make the steel have good high temperature oxidation resistance and oxidation medium corrosion resistance. It also increases the thermal strength of steel, and chromium is the main alloying element of stainless acid-resistant steel and heat-resistant steel. Chromium can improve the strength and hardness of carbon steel in the rolled state. Reduced elongation and section shrinkage.
2. The role of alloy steel alloy elements in steel The role of alloy steel alloy elements in steel Carbon (c): The carbon content in the steel increases, the yield point and tensile strength increase, but the plasticity and impact decrease, when the carbon content exceeds 23%, the welding performance of the steel deteriorates, so the carbon content of the low-alloy structural steel used for welding generally does not exceed 20%.
3. CR: Significantly improve strength, hardness and wear resistance, but reduce plasticity and toughness at the same time. Improve the oxidation and corrosion resistance of steel. The temperature of A3 and A1 is increased, and the GS line is shifted to the upper left. Chromium is a moderately strong carbide forming element.
4. CR: Significantly improve strength, hardness and wear resistance, but reduce plasticity and toughness at the same time. Improve the oxidation and corrosion resistance of steel.
The temperature of A3 and A1 is increased, and the GS line is shifted to the upper left. Chromium is a moderately strong carbide forming element.
5. The role of C, MN, SI, S, P, CR, MO elements in steel and the influence of heat treatment2022-05-0220·Cloud rolled steel chromium (CR) chromium can increase the hardenability of steel and have a secondary hardening effect. It can improve the hardness and wear resistance of high-carbon steel without making the steel brittle;When the content exceeds 12%.
1. Carbon (c): The carbon content in the steel increases, the yield point and tensile strength increase, but the plasticity and impact decrease, and the high carbon content will also reduce the atmospheric corrosion resistance of the steel, and the high-carbon steel in the open yard is easy to corrodeCarbon can increase the cold brittleness and aging sensitivity of steel.
2. The direct effect of alloying elements to form carbides is mainly diffusion strengthening, and it is possible to obtain some special properties (such as high temperature thermal strength). In some high-alloy steels, metal compounds such as FeSi, FeCr, Fe2W, Ni3Al, Ni3Ti, etc., may also form between the metal elements, and their role in the steel is similar to that of carbon compounds.
3. Effect on the basic phase in steel: a. Soluble in ferrite and play a curing role (the solid solution strengthening effect of Si and Mn is the most obvious) b. Formation of carbides (the affinity between alloying elements and carbon is in the order from small to large: ZR, TI, NB, V, W, MO, CR, MN, FE).
4. For detective work, the main classification may be the last type of classification mixed classification: classification according to the toxic effect of poisons: corrosive poison. Refers to poisons that have a strong corrosive effect on the body.
Such as strong acids, strong alkalis and phenols, etc.: substantial toxicity. After absorption, poisons with pathological damage to organ tissues are introduced.
5. What are the functions of the elements in alloy steel?The alloying elements added for alloying are silicon, manganese, chromium, nickel, molybdenum, tungsten, vanadium, titanium, niobium, boron, aluminum, etc. Their role in steel is explained separately.
6. The effect on the mechanical properties of steel a, when other alloying elements are added to improve the strength and hardness of steel, the effect is more significant. b. Significantly increase the brittle transition temperature of steel. c. In Fe-CR alloys with high chromium content, if there is phase precipitation, the impact toughness decreases sharply.