Development of heat treatment process for high grade chain steel 23MnNiMoCr54
Heat treatment determines the quality and performance of round link chain steel, so reasonable and efficient heat treatment process is an effective method to ensure good stability of high-grade chain steel.
The process of heat treatment of 23MnNiMoCr54 high grade chain steel
The medium frequency induction heating method has the characteristics of fast heating speed and less oxidation, which not only conforms to the current green production, but also reaches certain indexes of round steel link chain strength and toughness. The specific process of adopting medium frequency induction heat treatment is to adopt the medium frequency induction continuous furnace of high-power induction heating equipment first, to realize the division of round steel link chain quenching and tempering. The quenching and tempering temperature before the chain is put into fire is strictly controlled by infrared temperature measurement. Through the test in practice, it is found that the cooling medium for quenching and tempering is water, The water temperature is controlled below 30 ℃. The power of quenching heating should be controlled between 25-35kw, the chain speed should be controlled at 8-9hz and the temperature should be controlled between 930 ℃ -960 ℃, so that the hardness of hardened layer and chain can meet certain quality requirements. The heating power of tempering process is controlled at 10-20kw and the temperature is controlled at 500 ℃-550 ℃. The chain speed is maintained between 15 and 16Hz.
(1) In the early stage of making round steel link chain, the heat treatment method is radiant furnace, such as rotary hearth furnace. The convection furnace is used for tempering. This method needs long heating time and low efficiency, some of which also need long traction chain. In the whole heating process of the chain, due to the high degree of surface oxidation, it is difficult to get very fine austenite grains, which eventually leads to the general quality of the round steel link chain produced at that time. With the continuous development of heat treatment technology, the intermediate frequency induction heating method developed in the later stage is widely used, and the heat treatment quality of the round steel link chain has been significantly improved.
(2) Chain tempering technology, the initial use of uniform temperature tempering, the current. development of more stable is the medium frequency differential temperature tempering and uniform temperature tempering plus differential temperature tempering. The so-called uniform temperature tempering is to consider that the hardness of each part of the chain link is the same after tempering, but the chain link is made by welding. If the tempering temperature is too low, the welding joint is easy to fracture, and the chain link hardness is high, the friction between the outside of the straight arm and the middle shift of the conveyor is also very easy to produce cracks. If the tempering temperature is low, the toughness of the chain may also be reduced. Differential temperature tempering adopts induction heating, which is more suitable for the heating conditions of the chain, that is, the top of the chain shoulder has high hardness and wear resistance, and the straight arm has low hardness and good toughness. This heat treatment method can greatly improve the quality of the chain.
Post time: Jun-15-2021