Heat treatment quality is good or bad, and ultimately affect the performance of the components and the quality of life between the quality of the relationship is good or bad, and heat treatment machinery industry is big and clean large power consumption.
Rolling forming heat production waste water, waste gas, waste salt, dust, noise and electromagnetic radiation and other environmental pollution. Solution heat treatment of environmental pollution, the implementation of clean heat (or green heat treatment) was developed heat treatment technology development direction. In order to reduce sulfur dioxide, carbon monoxide, carbon dioxide, dust and cinder emissions, has been basically put an end to the use of coal as a fuel, extensive use less and less, rather than more for light oil, natural gas is still the best fuel.
Incinerator waste heat has reached a highly optimized structure and burner air - fuel ratio, strictly controlled to ensure reasonable under the premise of NOx and CO reduction to a minimum combustion gases using carburizing, carbonitriding salt bath and vacuum heat treatment technology alternative waste treatment to reduce salt and CN toxic contamination of water; water-soluble synthetic oil instead of part of the quenching oil quenching, the use of biodegradable vegetable oil instead of mineral oil to reduce oil pollution.
Metal after quenching a deformation of the deformation effect of the cooling process is also very important. Heat oil quenching oil quenching deformation is small, the general control of 100 ± 20 ℃. Oil cooling deformation capacity is essential. Quenching method of mixing and impact deformation rate. Metal heat cooling faster, more uniform cooling, the greater the pressure, the greater the mold deformation. Ensure mold hardness under the premise of using pre-cooling, to take classification, can significantly reduce the metal cooled quenching thermal stress and stress is to reduce some of the more complex shape of the workpiece deformation and effective manner; Some particularly complex or high-precision parts, Using isothermal quenching, can significantly reduce the deformation.
A carbon (C): carbon content in steel increases, the yield point and tensile strength rises plastic bearings have application scope is very broad, but the ductility and impact resistance decreases when the carbon content 0.23% exceeded, steel welding performance deterioration, so for welding low alloy steel, carbon content less than 0.20%. But it also reduces the amount of high-carbon steel resistant to atmospheric corrosion, in the open yard of high-carbon steel to easily corroded; addition, carbon steels can increase sensitivity to cold brittleness and aging.
2, silicon (Si): In the steelmaking process of Si as a reducing agent and a deoxidizing agent, so killed steel containing 0.15 to 0.30% silicon. If the silicon steel exceeds 0.50-0.60%, Si even if the alloy elements. To strengthen the rolling product IPR protection silicon can significantly improve the steel elastic limit, yield point and tensile strength, it is widely used as spring steel. In the quenched steel is added 1.0-1.2% silicon, strength can be increased by 15-20%. Silicon and molybdenum, tungsten, chromium, etc. combined with improved corrosion resistance and oxidation, can produce heat-resistant steel. Silicon 1-4% of low-carbon steel, with a high magnetic permeability, for electrical industry as silicon steel. Silicon increases, will reduce the weldability.
3, manganese (Mn): in the steelmaking process, manganese good deoxidizer and desulfurizer, generally steel, manganese 0.30-0.50%. In carbon steel, adding 0.70% or more, even if the "manganese", than the average amount of steel steel not only has sufficient toughness, and a higher strength and hardness of the steel hardenability of steel to improve the hot workability, If 16Mn steel than A3 yield point is 40% higher. Manganese 11-14% of steel with high wear resistance, used excavator bucket, ball mill liners and so on. Manganese content increased, decreased corrosion resistance of the steel, the country's largest production base for wind turbine bearings reduce welding performance.
4, phosphorus (P): In general, the phosphorus is the harmful elements in steel to increase the steel cold brittleness, the welding performance deterioration, lower ductility, the cold performance deterioration. So usually require steel phosphorus content is less than 0.045%, high quality steel required lower.
5, sulfur (S): Sulfur is usually the case is harmful elements. Internationally competitive industrial base of large bearing thermal brittleness of the steel and reduce the ductility and toughness of steel, forging and rolling in causing cracks. Sulfur on the welding performance is also detrimental to reduce corrosion resistance. So usually require a sulfur content of less than 0.055%, high-quality steel requirement is less than 0.040%. Added in the steel 0.08-0.20% of sulfur, can be improved machinability, commonly called cutting steel.
6, chromium (Cr): structural steels and tool steels, chromium can significantly improve strength, hardness and wear resistance, but lower ductility and toughness. Chromium also improve oxidation resistance of steel and corrosion resistance, so it is stainless steel, heat-resistant steel important alloying elements.
7, nickel (Ni): Nickel can improve the strength of steel, high-end bearing most dependent on yet maintain good ductility and toughness. Nickel acid has a higher corrosion resistance at high temperatures with rust and heat capacity. However, due to Nickel is relatively scarce resources, it should maximize the use of other alloying elements substitution of nickel chromium steel.
8, molybdenum (Mo):, molybdenum steel, grain refining, improving hardenability and thermal strength properties at high temperatures to maintain sufficient strength and creep resistance (long-term high temperature subjected to stress, deformation, called creep). Structural steel by adding molybdenum to improve the mechanical properties.
9, titanium (Ti): titanium in steel strong deoxidizing agent. Evaluating the selected appropriateness of accounting policies and making accounting estimates made by it can make steel internal organization of dense, fine grain power; reduce aging sensitivity and cold brittleness. Improve the welding performance. In the Cr 18 Ni 9 austenitic stainless steel by adding an appropriate Ti, to avoid intergranular corrosion.
10, vanadium (V): fine vanadium steel deoxidizer. Steel 0.5% vanadium can refine the organization grain, improved strength and toughness. Vanadium and carbon to form carbides, under heat and pressure to increase resistance to hydrogen corrosion.
11, tungsten (W): tungsten melting point higher than the major, is the raw alloying elements. Tungsten and carbon to form tungsten carbide has a high hardness and wear resistance. In tool steel plus tungsten Qingdao Swiss precision electromechanical constantly put quality Singshih strategy into deeper areas and at higher levels, can significantly increase the red hardness and heat resistance for cutting tools and forging mold.
12, niobium (Nb): niobium can refine the grain and lower steel thermal sensitivity and temper brittleness, improve strength, but the ductility and toughness decrease. In the ordinary low-alloy steels niobium, can improve the resistance to atmospheric corrosion and high temperature anti-hydrogen, nitrogen, ammonia corrosion. Niobium can improve the welding performance. In austenitic stainless steels niobium to prevent intergranular corrosion.
13, cobalt (Co): Cobalt is a rare precious metal, used for special steels and alloys, such as heat resistant steel and magnetic materials.
14, copper (Cu): Wuhan with Daye ores refining steel, often contain copper. Annual sales of hundreds of hundreds of millions of lucrative SKF Bearings agents can improve the strength and toughness of copper, in particular atmospheric corrosion. Disadvantage is that the thermal processing prone to thermal embrittlement, Cu content exceeds 0.5% of the plastic is significantly reduced. When the copper content is less than 0.50% on weldability no effect.
15, aluminum (Al): Aluminum is commonly used in steel deoxidizer. Company bearings domestic market share stable at around 65% -70% by adding a small amount of steel, aluminum, can be refined grain and improve the impact toughness, such as deep-drawing steel sheet 08Al. Alcoa also has antioxidant and anti-corrosion, aluminum and chromium, silicon combination, can significantly improve the steel at high temperature can not afford leather performance and high temperature corrosion. Aluminum disadvantage of steel and hot workability, weldability and machinability.
16, boron (B): a small amount of boron added steel can improve the density of steel and hot-rolled performance, increase strength.
17, nitrogen (N): Nitrogen can improve the strength of steel, covering the whole country and the world all fans supporting products low temperature toughness and weldability, increasing aging sensitivity.
18, RE (Xt): rare earth elements is in the periodic table of atomic number 57-71 15 lanthanides. These elements are metals, but their oxides are like "soil", it used to called rare earths. Added steel earth, can change the inclusions in steel composition, shape, distribution and properties, thereby improving the steel of the various properties such as toughness, weldability, cold workability. In the ploughshare added steel earth, can improve the wear resistance.
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