Quenching temperature and time of roller chain: analysis of key process parameters

Quenching temperature and time of roller chain: analysis of key process parameters

In the field of mechanical transmission, roller chain is a key component, and its performance directly affects the operating efficiency and reliability of mechanical equipment. Quenching, as the core heat treatment process in roller chain production, plays a vital role in improving its strength, hardness, wear resistance and fatigue life. This article will deeply explore the determination principles of roller chain quenching temperature and time, process parameters of common materials, process control and the latest developments, aiming to provide detailed technical references for roller chain manufacturers and international wholesale buyers, to help them deeply understand the impact of quenching process on roller chain performance and make more informed production and procurement decisions.

1. Basic concepts of roller chain quenching
Quenching is a heat treatment process that heats the roller chain to a certain temperature, keeps it warm for a certain period of time, and then cools it rapidly. Its purpose is to improve the mechanical properties of the roller chain, such as hardness and strength, by changing the metallographic structure of the material. Rapid cooling transforms austenite into martensite or bainite, giving the roller chain excellent comprehensive properties.

2. Basis for determining quenching temperature
Critical point of materials: Roller chains of different materials have different critical points, such as Ac1 and Ac3. Ac1 is the highest temperature of the pearlite and ferrite two-phase region, and Ac3 is the lowest temperature for complete austenitization. The quenching temperature is usually selected above Ac3 or Ac1 to ensure that the material is fully austenitized. For example, for roller chains made of 45 steel, Ac1 is about 727℃, Ac3 is about 780℃, and the quenching temperature is often selected at around 800℃.
Material composition and performance requirements: The content of alloying elements affects the hardenability and performance of roller chains. For roller chains with a high content of alloying elements, such as alloy steel roller chains, the quenching temperature can be appropriately increased to increase the hardenability and ensure that the core can also obtain good hardness and strength. For low-carbon steel roller chains, the quenching temperature cannot be too high to avoid severe oxidation and decarburization, which affects the surface quality.
Austenite grain size control: fine austenite grains can obtain fine martensite structure after quenching, so that the roller chain has higher strength and toughness. Therefore, the quenching temperature should be selected within the range that can obtain fine austenite grains. Generally speaking, as the temperature rises, austenite grains tend to grow, but appropriately increasing the cooling rate or adopting process measures to refine the grains can inhibit grain growth to a certain extent.

3. Factors determining quenching time

Size and shape of roller chain: larger roller chains require longer insulation time to ensure that the heat is fully transferred to the inside and the entire cross section is uniformly austenitized. For example, for roller chain plates with larger diameters, the insulation time can be appropriately extended.

Furnace loading and stacking method: Too much furnace loading or too dense stacking will cause uneven heating of the roller chain, resulting in uneven austenitization. Therefore, when determining the quenching time, it is necessary to consider the impact of furnace loading and stacking method on heat transfer, appropriately increase the holding time, and ensure that each roller chain can achieve the ideal quenching effect.
Furnace temperature uniformity and heating rate: Heating equipment with good furnace temperature uniformity can make all parts of the roller chain heated evenly, and the time required to reach the same temperature is shorter, and the holding time can be reduced accordingly. The heating rate will also affect the degree of austenitization. Rapid heating can shorten the time to reach the quenching temperature, but the holding time must ensure that the austenite is fully homogenized.

4. Quenching temperature and time of common roller chain materials
Carbon steel roller chain
45 steel: The quenching temperature is generally 800℃-850℃, and the holding time is determined according to the roller chain size and furnace loading, usually around 30min-60min. For example, for small 45 steel roller chains, the quenching temperature can be selected as 820℃, and the insulation time is 30min; for large roller chains, the quenching temperature can be increased to 840℃, and the insulation time is 60min.
T8 steel: The quenching temperature is about 780℃-820℃, and the insulation time is generally 20min-50min. T8 steel roller chain has a higher hardness after quenching and can be used in transmission occasions with large impact loads.
Alloy steel roller chain
20CrMnTi steel: The quenching temperature is usually 860℃-900℃, and the insulation time is 40min-70min. This material has good hardenability and wear resistance, and is widely used in roller chains in the automotive, motorcycle and other industries.
40Cr steel: The quenching temperature is 830℃-860℃, and the insulation time is 30min-60min. 40Cr steel roller chain has high strength and toughness, and is widely used in the field of industrial transmission.
Stainless steel roller chain: Taking 304 stainless steel as an example, its quenching temperature is generally 1050℃-1150℃, and the insulation time is 30min-60min. Stainless steel roller chain has good corrosion resistance and is suitable for chemical, food and other industries.

5. Quenching process control
Heating process control: Use advanced heating equipment, such as a controlled atmosphere furnace, to accurately control the heating rate and the atmosphere in the furnace to reduce oxidation and decarburization. During the heating process, control the heating rate in stages to avoid deformation of the roller chain or thermal stress caused by a sudden temperature rise.
Selection of quenching medium and cooling process control: Select a suitable quenching medium according to the material and size of the roller chain, such as water, oil, polymer quenching liquid, etc. Water has a fast cooling speed and is suitable for small-sized carbon steel roller chains; oil has a relatively slow cooling speed and is suitable for larger-sized or alloy steel roller chains. During the cooling process, control the temperature, stirring speed and other parameters of the quenching medium to ensure uniform cooling and avoid quenching cracks.
Tempering treatment: The roller chain after quenching should be tempered in time to eliminate quenching stress, stabilize the structure and improve toughness. The tempering temperature is generally 150℃-300℃, and the holding time is 1h-3h. The selection of tempering temperature should be determined according to the use requirements and hardness requirements of the roller chain. For example, for roller chains requiring high hardness, the tempering temperature can be appropriately reduced.

6. The latest development of quenching technology
Isothermal quenching process: By controlling the temperature of the quenching medium, the roller chain is isothermally stayed in the austenite and bainite transformation temperature range to obtain bainite structure. Isothermal quenching can reduce quenching deformation, improve the dimensional accuracy and mechanical properties of the roller chain, and is suitable for the production of some high-precision roller chains. For example, the isothermal quenching process parameters of C55E steel chain plate are quenching temperature 850℃, isothermal temperature 310℃, isothermal time 25min. After quenching, the hardness of the chain plate meets the technical requirements, and the strength, fatigue and other properties of the chain are close to those of 50CrV materials treated with the same process.
Graded quenching process: The roller chain is first cooled in a medium at a higher temperature, and then cooled in a medium at a lower temperature, so that the internal and external structures of the roller chain are uniformly transformed. Gradual quenching can effectively reduce quenching stress, reduce quenching defects, and improve the quality and performance of the roller chain.
Computer simulation and optimization technology: Use computer simulation software, such as JMatPro, to simulate the quenching process of the roller chain, predict changes in organization and performance, and optimize quenching process parameters. Through simulation, the influence of different quenching temperatures and times on the performance of the roller chain can be understood in advance, the number of tests can be reduced, and the efficiency of process design can be improved.

In summary, the quenching temperature and time of the roller chain are the key process parameters affecting its performance. In actual production, it is necessary to reasonably select the quenching temperature and time according to the material, size, use requirements and other factors of the roller chain, and strictly control the quenching process to obtain high-quality and high-performance roller chain products. At the same time, with the continuous development and innovation of quenching technology, such as isothermal quenching, graded quenching and the application of computer simulation technology, the production quality and efficiency of roller chains will be further improved to meet the growing market demand.