First, thermal processing
That the metallic material at the same time above the recrystallization temperature of plastic deformation and recrystallization processing method. Thermal processing typically involves casting, hot-rolling, forging, and metal heat treatment, sometimes including welding, hot cutting, and thermal spraying. Thermal processing enables the metal part to improve its structure while forming, or to change the formed part to a crystalline state to improve the mechanical properties of the part. For low melting point metal materials, such as lead , zinc , tin, etc., the recrystallization temperature is low, and plastic processing of them at room temperature is also a thermal process.
Second, annealing
A metal heat treatment process that slowly heats the metal to a temperature for a sufficient period of time and then cools it at a suitable rate (usually slow cooling, sometimes controlled cooling). The goal is to soften materials, or workpieces that have been cast, forged, welded, or machined, to improve plasticity and toughness, to homogenize chemical components, to remove residual stress, or to achieve desired physical properties. Annealing processes vary depending on the purpose, such as recrystallization annealing, isothermal annealing, homogenization annealing, spheroidizing annealing, stress relief annealing, recrystallization annealing, and stabilization annealing, magnetic field annealing, and the like.
1. When the metal tool is used, it loses its original hardness due to heat.
2. Slowly cool the metal material or workpiece after heating it to a certain temperature for a certain period of time. Annealing can reduce the hardness and brittleness of the metal and increase the plasticity. Also called bonfire.
One of the most important process parameters for annealing is the maximum heating temperature (annealing temperature). The annealing temperature of most alloys is selected based on the phase diagram of the alloy system. For example, carbon steel is based on the iron- carbon balance diagram. 1). The annealing temperature of various steels (including carbon steel and alloy steel) is a certain temperature of Ac3 or more and Ac1 or more of each steel grade depending on the specific annealing purpose. The annealing temperature of each of the non-ferrous alloys is below a solidus temperature of each of the alloys, and a temperature above or below the solidus temperature.
Third, quenching (in the industry, quenching the "zà n" sound, that is, reading "zà nhuǒ")
The metal workpiece is heated to a suitable temperature for a period of time, and then immersed in a quenching medium for rapid cooling of the metal heat treatment process. Commonly used quenching media are brine, water, mineral oil, air, and the like. Quenching can improve the hardness and wear resistance of metal workpieces, so it is widely used in various tools, molds, measuring tools and parts that require surface wear resistance (such as gears, rolls, carburized parts, etc.). Through quenching and tempering at different temperatures, the strength, toughness and fatigue strength of the metal can be greatly improved, and the combination of these properties (comprehensive mechanical properties) can be obtained to meet different application requirements. In addition, quenching can also obtain certain physical and chemical properties of some special properties of steel, such as quenching to make permanent magnet steel strengthen its ferromagnetism, stainless steel to improve its corrosion resistance. The quenching process is mainly used for steel parts. When the commonly used steel is heated above the critical temperature, the original or at room temperature will transform all or most of the microstructure into austenite. The steel is then immersed in water or oil for rapid cooling and the austenite is transformed into martensite. Martensite hardness is the highest compared to other structures in steel. The purpose of steel quenching is to convert all or part of its structure into martensite, obtain high hardness, and then temper at the appropriate temperature to give the workpiece the expected performance. Rapid cooling during quenching causes internal stresses in the workpiece, and when it is large enough, the workpiece will be distorted or even cracked. To do this, you must choose the right cooling method. According to the cooling method, the quenching process is divided into four types: single-liquid quenching, double-medium quenching, martensite-grading quenching and bainite austempering.
Fourth, cold rolling
The rolling performed below the recrystallization temperature is called cold rolling, and the hot rolled steel coil is generally used as a raw material, and the scale is removed by pickling to perform cold rolling, and the finished product is a rolled hard roll, which is hardened by continuous cold deformation. The strength and hardness of the rolled hard roll are increased, and the toughness index is lowered. Therefore, the punching performance is deteriorated and can only be used for parts that are easily deformed. Rolled hard rolls can be used as raw materials for hot-dip galvanizing plants because the hot-dip galvanizing units are provided with an annealing line. The rolling hard roll weight is generally 20-40 tons, and the steel coil is continuously rolled on the hot rolled pickling roll at normal temperature. The inner diameter is 610mm.
Product features: Because it has not been annealed, its hardness is very high (HRB is greater than 90), and the machining performance is extremely poor. Only a simple directional bending process of less than 90 degrees (perpendicular to the winding direction) can be performed.
Simple little, the cold rolling is processed on the basis of hot rolled coil rolled out, in general hot rolling - pickling - phosphine - saponification - such cold rolling process.
Cold rolling is processed from hot-rolled sheets at room temperature, although the steel sheet is heated during the processing because of rolling, although it is called cold rolling. Since the cold rolling of the hot rolling through the continuous cold deformation is poor in mechanical properties and the hardness is too high, it is necessary to be annealed to restore its mechanical properties, and the unrolled is called a hard rolled coil. Rolled hard rolls are generally used for products that do not require bending or stretching. The thickness of 1.0 or less is hard and good for both sides or four sides.
Supplementary correction: Cold rolling is generally annealed.
Cold rolling oil must be used in the cold rolling process. The advantages of using cold rolling oil are: 1. Effectively reduce the friction coefficient, provide corresponding rolling force, low rolling energy consumption, and obtain satisfactory rolling parameters; 2. Make surface light High brightness, uniform rolling thickness; 3, good cooling effect, can quickly take away the rolling heat, protect the rolls and rolling parts. Good annealing performance, no oil burning phenomenon; 4, short-term anti-rust performance, can provide temporary rust protection of rolling stock.
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