1.Chemical forming parameters of high carbon steel
2. Performance characteristics of high carbon steel
1.High hardness (HRC60-65) and good wear resistance can be obtained after heat treatment.
2. Under annealing condition, the hardness is moderate and the machinability is good.
3. Raw materials are readily available and production costs are low.
1.Poor thermal hardness, when the tool working temperature is greater than 200℃, its hardness and wear resistance sharply decreased.
2. Hardenability is low. In water quenching, the diameter of completely quenched is generally only 15 to 18mm; The maximum diameter or thickness of oil quenching is only about 6mm, and it is easy to deform and crack.
The above are the advantages and disadvantages of high carbon steel, pay attention to when in use：The hardness and strength of high carbon steel are mainly determined by the amount of dissolved carbon in the steel, and increase with the increase of dissolved carbon. When the solution carbon content exceeds 0.6%, the hardness does not increase after quenching, but the amount of excess carbide increases, and the wear resistance of the steel increases slightly, while the plasticity, toughness and elasticity decrease. To this end, often according to the conditions of use and the strength of steel, toughness match to choose different steel. For example, low carbon 65 steel can be used to make spring or spring parts with low stress. General high carbon steel can be produced by electric furnace, open hearth furnace and oxygen converter. When high quality or special quality is required, electric furnace smelting plus vacuum consumptions or electroslag remelting can be used. When smelting, strict control of chemical composition, especially sulfur and phosphorus content. To reduce segregation and improve isotropic properties, ingot steel can be annealed at high temperature by diffusion (especially important for tool steel). Hot processing, the stop forging (rolling) temperature of eutectoid steel is low (about 800℃), after forging and rolling material should avoid the precipitation of coarse network carbide, below 700℃ should pay attention to slow cooling, in order to prevent cracks caused by thermal stress. Surface decarbonization should be prevented during heat treatment or hot working (especially for spring steel). Thereshould be enough compression ratio during hot working to ensure the quality and performance of steel.
3.Welding process of high carbon steel
When we use high carbon steel for welding, a note should be taken that it carbon content is high, the weldability is poor, welding to preheat, welding to slow cooling or 350 degrees of low temperature tempering, the length of the specific heat treatment is determined by the thickness of the workpiece. If you can't preheat, you have to use welding materials with good welding performance and good crack resistance, but the welding speed must be reduced.
(1) In order to obtain high hardness and wear resistance of high carbon steel parts, the material itself needs to be heat treated, so annealing should be carried out before welding.
(2) Welding parts should be preheated before welding, the preheating temperature is generally above 250 ~ 350℃, during the welding process, it is necessary to keep the temperature between layers not lower than the preheating temperature.
(3) After welding, the weldment must be kept warm and cooled slowly, and immediately sent to the furnace for stress relief heat treatment at 650℃.
4. Application of high carbon steel
According to the characteristics of high carbon steel with high strength and hardness, high elastic limit and fatigue limit after proper heat treatment or cold-drawing hardening, it is often used in manufacturing cutting, drilling, lathes, milling machines, cutting tools and so on
5.Difference between high carbon steel and low carbon steel
1. Carbon content
From the carbon content above, high carbon steel content is between 0.6%~1.7%, low carbon steel content is generally less than 0.25%. Secondly, from the hardness above, high carbon steel it is hard, and low carbon steel its hardness is lower, so it is softer, there is another scientific name called soft steel
High carbon steel is relatively hard, can be used as drill or reamer, and low carbon steel is relatively soft, basically in use without heat treatment, and some can be used for wear-resistant machinery manufacturing and accessories manufacturing.
The performance of high carbon steel is better. Its hardness, strength is higher than low carbon steel, and due to the increase in carbon content, will lead to the cost of raw materials increase, so the price will be higher than low carbon steel.
6. Ultra-high carbon steel
Ultra-high carbon steel is an iron - based alloy material with a carbon content of 1.0-2.1%. One of the earliest industrial examples of ultra-high carbon copper was in Damascus. Its carbon content is 1.5%. In the middle of 1970s, The Study on superplasticity of ultra-high carbon steel was first carried out by Stein Institute in the United States, and then the research on ultra-high carbon steel was also carried out by the National laboratory in the United States. And obtained a series of patents. In addition. Japan and other countries have also carried out research on ultra-high carbon steel. In the 21st century, China has also carried out research on ultra-high carbon steel. Ultra - fine crystal ultra - high carbon steel without network carbides was obtained by appropriate preparation technology. It not only has the superplastic property of high deformation rate at medium and high temperature. Moreover, it has good comprehensive mechanical properties at room temperature. Ultra-fine crystal ultra-high carbon steel is not only expected to replace some of the middle and high carbon steel to make molds, steel wires and structural parts, so as to significantly improve its service life, but also can be used to connect with itself or other metal base materials to prepare a new type of high-performance lamellar composite. It is a kind of new material with great prospect of industrial application