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Characteristics and using process of high speed steel roll

Characteristics and using process of high speed steel roll

High-speed steel roll is a hot-rolled material with rapid development and wide application in recent years. Its composition is more complex alloy steel. Can harden. The working layer is made of high carbon steel, and the roller core is made of ductile iron, graphite steel or forged steel. The two different materials are compounded by centrifugal casting or CPC process. The matrix structure is generally tempered martensite bainite carbide, and the carbide is distributed in the matrix in a highly dispersed form, so it has high wear resistance and toughness, which makes turning difficult. So, let's take a look at the characteristics and use of high-speed steel rolls. High-speed steel roll features: good thermal stability, good hardenability, high carbide hardness, easy to form oxide film, thermal cracking resistance and good wear resistance, the requirements for cooling water is far lower than that of cemented carbide. Requirements, its single groove rolling capacity can reach 45 times the cast iron roll. It is beneficial to the negative tolerance control of the rolled material and improve the surface quality of the rolled material. It is mainly aimed at the application of online bar products and finished front frames, as well as the development of new material coils for slitting and rolling pre-cutting and slitting passes. The hardness can reach HSD78-90, high wear resistance, good impact resistance and good thermal fatigue resistance. With the popularity of high-speed steel roll online bar mill, R & D manufacturers quickly spread out. But the manufacturers in high

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2023

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05

Advantages of high speed steel roll

Advantages of high speed steel roll

High-speed steel roll is a high-carbon high-speed steel composite roll, which has become an important part of the development of modern rolling production. After 20 years of development, it has been widely used in rolling mills all over the world. At present, cast high-speed steel rolls are not only widely used in the finishing stands of cold and hot strip steel hot rolling mills, but also in the finishing stands of wire and bar mills. Is a very good application, then, let's take a look at the advantages of high speed steel roll. The advantages of high-speed steel rolls: 1. High hardness of carbides: The rolls used in the past mostly distribute Fe3C or M7C3 eutectic carbides on the matrix, with coarse organization and low hardness. High-speed steel rolls generally use high-C, high-V high-speed steel, but also contain more Cr, Mo, W, Nb, Co and other alloying elements. During solidification and heat treatment, these alloying elements form primary and secondary carbides. Things. High chromium cast iron roll carbide M7C3(2500Hv) and M23C6(1600Hv). In the infinite chilled cast iron roll, the carbide is Fe3C(l300Hv). 2, good thermal stability: high speed steel roll contains more W, Cr, Mo, V, Nb and other elements, good thermal stability. The study found that the hardness of ordinary roll material with temperature

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2023

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05

The role of tungsten and molybdenum in high-speed steel rolls

The role of tungsten and molybdenum in high-speed steel rolls

The role of tungsten and molybdenum in high-speed steel rolls Tungsten and molybdenum are the main alloying elements in ordinary high-speed steel rolls. The chemical properties of tungsten and molybdenum are similar, and their effects on the microstructure transformation and properties of high-speed steel rolls are almost the same. The difference is that molybdenum causes a lower temperature of the structural transition. The main reason for using high-speed steel to manufacture rolls is to use the excellent red hardness of high-speed steel to improve the high-temperature wear resistance of rolls. The excellent red hardness of high-speed steel rolls is firstly attributed to the strong aggregation resistance of M2C and MC. A large amount of retained austenite can also be obtained in the quenched structure of ordinary carbon steel and low alloy steel. Decomposition of this retained austenite at high temperatures rarely increases the hardness. The austenite in these steels usually decomposes at a lower temperature, while the precipitated Fe3C type carbides rapidly aggregate at a slightly higher temperature, and the aggregation of carbides is the direct cause of softening. In high-speed steel, the precipitation of carbides into very fine particles and the decomposition of residual austenite jointly cause secondary hardening, and the carbides always maintain their fine size, so high-speed steel has good red hardness. In high-speed steels, the elements that influence this phenomenon are tungsten and molybdenum. The atomic size of tungsten and molybdenum in high-speed steel is much larger than that of any other element, and the diffusion rate is slower. In order for carbides to continue to accumulate, not only chromium is needed.

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2022

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What is the role of chromium in high speed steel rolls?

What is the role of chromium in high speed steel rolls?

What is the role of chromium in high-speed steel rolls? Chromium in high-speed steel is partially present in M6C type carbides and can also form M23C6 type carbides. M23C6 can be completely dissolved at a lower quenching temperature, so that the solid solution can reach carbon chromium saturation without affecting the grain size. Chromium can also promote the complete dissolution of M6C in austenite, thereby improving the hardenability and red hardness of high-speed steel. In addition, when high-speed steel is tempered at 450-525°C, a part of chromium precipitates from martensite, which promotes dispersion hardening; another part of chromium remains in solid solution a to prevent softening when heated to higher temperatures. Adding 3%-4% chromium can obtain three times slightly higher hardness. Chromium can also significantly reduce oxidation in high speed steels. However, if the chromium content is too high, the excess chromium will participate in the formation of carbides precipitated during tempering. Such chromium-containing carbides tend to precipitate at lower temperatures, reducing the thermal stability of high-speed steels. If the chromium content is too high, the unevenness of the carbides also increases. Since chromium increases the amount of M7C3 carbides in high-speed steel rolls and reduces the amount of MC carbides, and the hardness of M7C3 carbides is lower than that of MC carbides, which is detrimental to wear resistance. However, for rolls with low chromium content

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2022

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Introduction of Roller Development

Introduction of Roller Development

Introduction to the development of the main working parts and tools for the continuous plastic deformation of metals on the rolling mill. The roll is mainly composed of three parts: roll body, roll neck and shaft head. The roll body is the middle part of the roll, which actually involves rolling metal. It has a smooth cylindrical or grooved surface. The roller neck is installed in the bearing, and the roller force is transmitted to the frame through the bearing seat and the pressing device. The shaft head at the transmission end is connected with the gear seat through the connecting shaft, and the rotating torque of the motor is transmitted to the roller. The rolls can be arranged in a two-roll, three-roll, four-roll or multi-roll arrangement in the roll stand. With the development of metallurgical technology and the development of rolling equipment, the variety and manufacturing process of rolls are also developing. In the Middle Ages, low-strength gray cast iron rolls were used to roll soft non-ferrous metals. In the middle of the 18th century, Britain mastered the technology of producing cold cast iron rolls for rolling steel plates. In the second half of the 19th century, the progress of European steelmaking technology required the rolling of large tonnage ingots, whether gray cast iron rolls or chilled cast iron rolls, their strength could not meet the requirements. The birth of the carbon content of 0.4% ~ 0.6% of the ordinary cast steel roll. The emergence of large-scale forging equipment has further improved the strength and toughness of the forging roller of this composition. In the early 20th century, the use of alloying elements

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2022

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The role of rolls in the rolling mill production line!

The role of rolls in the rolling mill production line!

The role of rolls in the rolling mill production line! The roll includes the main equipment, auxiliary equipment, lifting and transportation equipment and auxiliary equipment, each of which is very important and indispensable. A roll is a machine that rolls steel between rotating rolls. Rolling mills are said to have appeared in Europe in the 14th century. Continuity, automation, specialization, high quality and low consumption are the development trends of modern rolling mills. The working frame of the rolling mill is used to install the frame and is fixed on the foundation, also known as the floor. To bear the dead weight and dumping moment of the work frame, while ensuring the accuracy of the installation size of the work frame. So, what does the work of the rolling mill include? The main equipment of the rolling mill is the work frame and the transmission device. The machine base is composed of roll, roll bearing, frame, guide rail seat, roll adjusting device, upper roll balancing device and roll changing device. The roll is an important part of the roll in the rolling mill. It uses the pressure generated by a pair or set of rolls to roll steel. It mainly bears the influence of rolling brake, static load, wear and temperature change. Roll is divided into hot roll and cold roll. The role of the roll in the rolling mill production line is crushing. For example, a 3mm thick steel plate is rolled to a thickness of 0.5mm by a rolling mill. Different working conditions of the roller material is very different. Generally speaking, it uses materials with high hardness, high strength and small deformation. In

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2022

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Classification of rolls

Classification of rolls

Classification of rolls There are many classification methods for rolls, mainly including:(1) according to product types, they are divided into strip steel rolls, special-shaped steel rolls, wire rod rolls, etc. (2) according to the position of the rolls in the rolling mill series, there are open rolls, rough rolls, fine rolls, etc. (3) according to the roll function, it is divided into scale breaking rolls, perforated rolls, leveling rolls, etc. (4) according to the material of the rolls, there are steel rolls, cast iron rolls, carbide rolls, ceramic rolls, etc.;(5) according to the manufacturing method is divided into casting rolls, forging rolls, surfacing rolls, inlaid rolls, etc.;(6) according to the state of rolled steel is divided into hot rolls and cold rolls. Various categories can be combined accordingly, so that the roll has a clearer meaning, such as centrifugal casting of high chromium cast iron work rolls for hot strip steel. Common drum materials and uses are shown in the table. The performance and quality of a roll generally depends on its chemical composition and manufacturing method, and can be evaluated by its microstructure, physical and mechanical properties, and the type of residual stress inside the roll (see roll inspection). The effect of the roll on the rolling mill depends not only on the material and metallurgical quality of the roll, but also on the conditions of use of the roll, roll design, operation and maintenance. The rolling conditions vary greatly for different types of mills. The factors contributing to the difference are:(1) mill conditions. such as mill type, rolling

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